Engineering Research Centers Program Directorate for Engineering National Science Foundation FY 2004-06 Solicitation (NSF 04-570) Site Visit Report

licoricehealthΤεχνίτη Νοημοσύνη και Ρομποτική

14 Νοε 2013 (πριν από 4 χρόνια και 1 μήνα)

195 εμφανίσεις

Engineering Research Centers Program

Directorate for Engineering

National Science Foundation


FY 2004
-
06 Solicitation (NSF 04
-
570)

Site Visit Report

Annotated in Response to Issues Raised, January 3, 2006




Engineering Research Center for Compact and Eff
icient Fluid Power

A Proposed Engineering Research Center (Proposal #0540834)


Center Director: Professor Kim A. Stelson

Lead University: University of Minnesota, Twin Cities

Core Partners: Georgia Institute of Technology, Purdue University,
University of
Illinois, Urbana
-
Champaign, and Vanderbilt
University


December 13
-
14, 2005



Site Review Team


Dr. James Bobrow

Department of Mechanical Engineering

University of California, Irvine

Irvine, CA

Massachusetts Institute of Technology (visiting)

Cambridge, Ma
ssachusetts


Dr. Sabri Cetinkunt

Department of Mechanical and Industrial Engineering

University of Illinois at Chicago

Chicago, IL


Dr. Lesia Crumpton
-
Young

Department of Industrial Engineering and Management Systems

University of Central Florida

Orlando,

FL


Dr. Mark R. Cutkosky

Department of Mechanical Engineering

Stanford University

Stanford, CA


2


Dr. Saeid Habibi

Department of Mechanical Engineering

University of Saskatchewan

Saskatoon, Saskatchewan, Canada


Dr. Sridhar Kota

Department of Mechanical En
gineering

University of Michigan

Ann Arbor, MI


Dr. Andras Szeri

Department of Mechanical Engineering

University of Delaware

Newark, DE


Dr. Tsu
-
Chin (T
-
C) Tsao

Department of Mechanical and Aerospace Engineering

University of California Los Angeles

Los An
geles, CA


ERC Panelist Members


Dr. Larry Fehrenbacher

Technology Assessment and Transfer, Inc.

Annapolis, MD


Dr. Greg Pottie

Department of Electrical Engineering

University of California, Los Angeles

Los Angeles, CA


NSF Staff


Dr. Bruce M. Kramer,

Sen
ior Advisor for Engineering and Lead ERC PD,

Division of Engineering Education and Centers


Dr. George Hazelrigg,

Group Leader, Design and Manufacture Research Programs

Division of Design, Manufacturing, and Innovation


3


A.


Executive Summary

Intellectual
Merit

Is the ERC focused on a transformative engineered system(s)? Does the strategic plan target
and organize a high quality and integrated research program with challenging barriers to
achieve the systems goals? How important is the activity to advancin
g knowledge and
understanding within its own field or across different fields? To what extent does the activity
suggest and explore creative and original concepts? How well qualified is the team to
conduct the project? How well conceived and organized is
it? Is there sufficient access to
resources?





The proposed ERC has research and educational efforts in an area that is critical to future
technological advances in our country and abroad. Advances in fluid power are needed to fully
realize the creatio
n of critical portable or mobile complex systems that require a fuel source.
Also, it appears that the proposed research activities can significantly impact the areas of
specialization within the field of Mechanical Engineering. The proposed research
not only
identified the importance of fluid power across several US industries but also addressed several key
challenges. The ERC team consists of well
-
qualified and highly talented group of researchers from
reputed institutions. The applications of propos
ed research span a wide range of industries from
compact assistive devices for disabled humans, to rescue operations, to agricultural and excavating
equipment. The proposed research and the team are well poised to make significant advances in
modeling and
control of fluid power systems, including advances in throttling and phase
-
change
energy storage. The ERC has the potential to advance fundamental research in many areas including
control theory, fluid mechanics, biomimetic design, tribology, and haptics.

The ERC has extremely
strong support and commitment from 48 industrial partners, from small companies to billion dollar
companies. Over a dozen CEOs from various companies spent a day during the site visit to share
their passion for and commitment to supp
orting the work of this proposed ERC. The team members
from all core institutions are very committed to and passionate about the proposed work and many
team members have collaborated on fluid power research in the past. The site visit team has full
confide
nce in the commitment of Dr. Kim Stelson to the ERC effort. The ERC has sufficient
physical resources, such as a newly renovated building at the University of Minnesota, an existing
7000 square foot fluid power laboratory at Purdue, rich existing infrastr
ucture at the Milwaukee
School of Engineering, and various other impressive laboratories and facilities at Georgia Tech and
Illinois. The ERC has strong support of administrators at the core institutions and all of them
attended the site visit to show thei
r commitment. The Center Director, university administrators and
industry partners have already established a memorandum of understanding regarding intellectual
property rights and technology transfer methods. During the site visit, the Center Director sha
red a
process for project selection, including evaluation criteria and metrics that are in concert with the
ERC goals, and a plan to include input from various stakeholders including the industry advisory
board.


Overall, the proposal did not quantitative
ly justify specific saving calculations in energy and
improvements in compactness. A minor fraction of the proposed projects seemed unrealistic and
not well thought through in terms of fundamental hypothesis and technical f
easibility. There seems
to be a
disconnect between some of the claims in efficiency and compactness and the project
outcomes. For instance, an order of magnitude improvement in power density of actuators suitable
for orthotic devices cannot be scaled
-
up to reap similar gains in the autom
otive sector. In addition,

4

the case made for hydraulic regenerative braking in passenger vehicles was not found to be very
compelling.


Response
:


Overview.

We agree with the overall characterization of the ERC by the Site Visit Committee. We
would like to

reiterate the transformative nature of the ERC with regard to energy. The main
sectors where fluid power is currently used are agriculture, mining, construction and
manufacturing. If the overall efficiency of these sectors were improved by 10%, an annual
energy
savings of $7.0 billion would result. Such a savings is realistic with the application of research from
the ERC. With improvements in the compactness of fluid power energy storage, a fluid power
hybrid vehicle could be developed that would be superi
or to current electric hybrids. Such a vehicle
could conservatively reduce the fuel consumption of passenger cars by 10% for an annual savings
of $10.0 billion.


Quantification of Energy Savings.

As an example, e
ne
rgy savings

in an excavator can be qu
antif
ied

(Eggers, et. al,

2005
)
.
T
hrottling los
ses are 18
%, pump
losses are 18%, line losses are 2% and
cylinder losses are

2%.
There is a

connection between each loss and research projects in the center
to reduce that
loss.

Projects 1A and 1E will eliminate th
rottling losses and enable regeneration
;

project 1B and 1C will reduce pump losses
;

pro
ject 1D will reduce line losses;

and project 3D will
reduce cylinder losses. Throttling could be almost completely eliminated with advanced control
approaches. Pump loss
es could be reduced by one third with the proposed approach. Line losses
could be reduced by 30 to 40%.

If
research in
throttle
-
less control
, regeneration, and biomimetic
nano
-
surfaces were

applie
d to an excavator, the projected overall

increase in efficie
ncy would be
30%. If the overall efficiency of earthmoving equipment were increased by 30%, an annual energy
savings of $1.15 billion

would result
.


Analogous estimates can be made for other fluid power applications.

For example, a 180 ton
hydraulic injec
tion molding machine requires 32.1 kW

of power,

3.2 kW

for the heaters, and
28.9
kW for the hydraulics.

23.9 kW

of power are used

to
overcome
throttling losses. Thus, if throttl
ing
losses were completely eliminated from

injection molding machines, the pow
er required could be
reduced from 32.1 kW to 8.2
kW for a potential

energy savings
of

74%.


Quantification of
Compactness
.

Quantitative estimates for improvements in compactness can also
be
made for
some of the projects.
T
he open accumulator concept would
increase the energy density
for fluid power storage by a factor of twelve. This would have a profound effect on fluid power use
in transportation

by

allowing technology that is currently limited to heavy trucks to be applied to
smaller vehicles such as pas
senger cars.


Scale up of C
hemo
-
fluidic A
ctuation.

T
he order of magnitude improvement in power density of
actuation possible with chemo
-
fluidic actuation would
not
be scaled up to the automotive sector.

This
technology

is intended for
portable, untethered

human scale applications.

C
urrent fluid power
actuation technology for the automotive sector is
adequate for
the development of
a
hydraulic
hybrid automobile.
The
most important technical barrier
for the automotive secto
r is not actuation
power density
, b
ut rather

energy storage density.


Project Feasibility.

We believe that the projects proposed
form

an appropriate set of initial projects
representing reasonable risk and payback, and a balance of
short and long term objectives.

5

Comments concerning projec
ts will be addressed in the Strategic Research Plan and Research
Program section.


Case for Hydraulic Hybrid Vehicles.

The case for hydraulic regenerative braking in pa
ssenger
vehicles is compelling

(Millet, 2004;
Ehrenman
, 2004)
.
In comparing hydraulic a
nd electric hybrid
vehicles, tradeoffs between size, cost, fuel economy and performance must be considered. Hybrid
vehicles, whether electric or hydraulic, improve fuel efficiency through the use of regenerative
braking in driving situations with frequent
stops and starts. Hybrid systems also enable the engine
to operate at its most efficient operating point.


A very significant advantage for hydraulic hybrids over electric hybrids is power density; replacing
electric motors with equivalent power hydraulic
motors will result in significant weight reduction
both in the motors and in the supporting structures. This allows the same system to have improved
performance (acceleration) or a smaller system to achieve the same performance.


Another significant advant
age for the hydraulic hybrid is regenerative braking efficiency. Existing
hydraulic hybrid regenerative braking for trucks

and SUVs

has a recovery efficiency of
greater than
7
0% while recovery efficiency for electric hybrid automobiles is less than 50%. Th
e inefficiency of
electric regenerative braking is surprising given the efficiency of motors and batteries, but this
inefficiency is a direct consequence of the power density limitations of batteries and motors.
Efficient battery recovery requires a trickl
e charge and the large power requirements of braking
inevitably lead to energy losses. Ultra
-
capacitors provide a potential energy buffer, but cost and
size limit their current use. Further, the low power density of
electric
m
otors causes designers to
choo
se

designs with undersized motors to keep the overall vehicle weight within reason. These
undersized motors cannot provide sufficient deceleration in hard braking situations, and some of
the kinetic energy must

be

lost as
heat.


The hydraulic hybrid approa
ch is the method of choice for heavy vehicles and is currently being
developed for military trucks, refuse trucks and city buses.
The
EPA has recently demonstrated the
technology on a hybrid SUV where a 55% improvem
ent in fuel economy was achieved.
The
EPA

estimates

that the
additional cost of
adding hydraulic hybrid capability to an SUV would be
$650

with mature manufacturing capability
. This
estimate may be low, but the actual amount promises to
be much less than the current additional cost of

$3000 to $6
000 for hybrid electric vehicles. One

current

advantage that electric hybrids have over hydraulic hybrids is energy storage density. Some
of the research projects in the ERC are directly targeting this barrier with potential energy density
improvements for

fluid power estimated to be in the range of two to twelve for various approaches.
Other advantages that electric hybrids have over hydraulic hybrids are quietness, cleanliness, and
precision of control. These are issues that the ERC will address. If the e
nergy density of fluid power
storage can be increased, and the noise
,

cleanliness
,

and control precision issues resolved, the
result will be a hybrid technology that would be applicable to passenger cars, the largest segment
of the transportation market. A

hydraulic hybrid passenger car would have great market

appeal
because of its lower

cost and increased performance compared
with
electric hybrids.


Hybrid electric vehicles have benefited from many decades

of research

and large amounts of
funding. This has

resulted in improved components such as batteries and motor/generators.
Hydraulic hybrids, on the other hand, have received much less attention. Yet, hydraulic hybrids

have

already demonstrated significant promise. With increased research targeted at hydr
aulic
hybrids, rapid
and significant
improvements can be expected.


6


References


Eggers, B.; Rahmfeld, R.; Ivantysynova, M. 2005. An energetic comparison

between valveless and
valve controlled active vibration damping for off
-
road

vehicles. 6th JFPS Inter
national Symposium
on Fluid Power. Tsukuba, Japan.

pp. 275
-
283.


Millet, J., “EPA Displays the First Advanced Hydraulic Hybr
id Vehicle,” EPA press release,
March 3, 2004.


“Hydraulic Hybrid Technology: A Proven Approach,” EPA report EPA420
-
F
-
04
-
024, March

2004.


“World’s First Full Hydraulic Hybrid SUV Presented at 2004 World SAE Congress,” EPA report
EPA420
-
F
-
04
-
019, March 2004.


Ehrenman, G., “Hybrids Go Hydraulic,


Mechanical Engineering, Sept. 2004.


Strengths



Compelling vision for the future of fluid
power;



Strength, commitment, enthusiasm, and involvement of the industrial members;



Established strength of the participating faculty in fluid power research;



Strong leadership and coordination between the Director and the Deputy Director
and among the par
tner institutions and companies;



Commitment of 10
-
12 new faculty hires to the ERC by the partner universities;



Commitment of new space and laboratories by the universities.


Weaknesses



Some of the projects may be unrealistic, may not fit the major thrust o
f the
proposed center, and should be considered for elimination;



Cost, manufacturability and reliability should be considered, even in the early
stages of research.


Response
:


Project Realism.

It is our belief that the initial
collection of projects pres
ented in the proposal is

the
optimum set to achieve advances in the three research thrust areas. Some of the projects have
significant unknowns that will not become clear until the initial phase of the research

is complete,
while other projects are high ri
sk, but with the potential for high payoff. Our project planning and
evaluation process will be used to weed out projects that become unrealistic or that take directions
that do not fit the thrusts of the Center.


The mission of the ERC is supported by a f
ive
-
year strategic plan. The strat
egic plan is a “living”
plan meaning that it
will be
modified annually to reflect evolving understanding that comes with
research progress.

To be eligible for
ERC
funding,
each project
must be al
igned with the vision of
th
e C
enter.

Approximately 90% of the funding will be for projects in the strategic plan. The
remaining 10% of the funds will be used as seed funding for high
-
risk, high
-
payoff research. The
proposed research projects will be evaluated by
the Scientific Advi
sory Board and

the Industrial

7

Advisory Board.
Based on this evaluation, projects

will be

funded as

pa
rt of the strategic plan,
funded
as

one of the seed funding projects
, or rejected
.
If any proposed project is judged to be
unrealistic or not well thought
through in terms of fundamental hypothesis and technical feasibility,
it will not be funded.


Cost, Manufacturability and Reliability.

We agree with the Site Visit Team
report
that cost,
manufacturability
,

and reliability should be considered, even in the
early stages of research. We
will incorporate these factors as metrics into the project plan for each project. Expertise for
evaluation of cost, manufacturability and reliability exists within the ERC, the Scientific Advisory
Board
,

and especially the Indu
strial Advisory Board. For projects where significant barriers of
cost, manufacturability or reliability prevent the use of otherwise promising technology, new
resear
ch projects within the ERC will

be proposed to tackle these barriers.



Broader impacts

How well does that activity advance discovery and understanding while promoting teaching,
training, and learning? Will the research be integrated into curricular materials for
students at all levels? Will the pre
-
college program serve to motivate students

to pursue
engineering careers? How well does it broaden the participation of underrepresented
groups (e.g. gender, ethnicity, disability, geographic, etc.)? To what extent does it enhance
the infrastructure for research and education, such as facilities,

instrumentation, networks,
and partnerships? Is there a strong, active partnership with industry/practitioners that will
strengthen the ERC and speed technology transfer? Are the results disseminated broadly to
enhance scientific and technological unders
tanding? What are and may be the benefits to
society?


The key societal benefits of this proposed ERC include enhancing the competitiveness of the fluid
power industry in the U.S. through training and education of skilled engineers in fluid power
technolo
gy, technological advances in computer aided modeling, optimization and control, and
development of energy efficient devices and systems. The site visit team was impressed by the
stated interest and commitment by university researchers, administrators and
industrial partners to
education efforts in Fluid Power at all levels


middle school through graduate programs. There is
involvement of HBCUs and collaborations with programs such as FACES (Academic Careers in
Engineering and Science) at Georgia Tech, Emo
ry, Spelman and Morehead and the Louis Stokes
Alliance for Minority Participation (LSAMP) program at North Carolina Agriculture and
Technology University (NCA&T), an outreach institution of the ERC.


The education and outreach efforts of the proposal inclu
de plans for new curricula at the
undergraduate and graduate levels, as well as ideas for Research Experiences for Undergraduates
(REU) activities. Also, the PIs propose to work with Project Lead the Way to influence the
development of materials for high
school students to increase their awareness of Engineering as a
career option. In addition, the ERC team plans to work with the Minneapolis Museum of Science to
develop a hands
-
on interactive module to explain the concepts of fluid power to children of al
l ages.
The proposal lacked a few specifics of the exact plans for educational programs and some of the
plans for curriculum development were not fully disclosed in the proposal. During the site visit,
additional questions were asked and information was
provided to assure the team of the research
driven approach that will be used to develop the education and outreach activities to ensure that the
goals of the education and outreach components are attained. The site visit team was assured that

8

the outreac
h efforts of the ERC would be guided using research findings and best practices learned
from informal education and prior outreach efforts targeted at increasing awareness and attracting
students to pursue careers in STEM fields. Given information presente
d during the site visit, it is
envisioned that the research findings from the work of the proposed ERC will be successfully
integrated into existing courses within the curriculum that will expose students to the topic and
broaden their understanding of the

fundamental theories, principles, and practices that are needed to
ensure their preparation for performing work

in the area of fluid power.
The additional information
shared during the site visit provided examples of activities that will be undertaken at
all of the
institutions involved to ensure that efforts associated with broadening the participation of females
and members of underrepresented groups are a top priority of the Center.


Strengths



Diversity of the leadership team and commitment of partner

universities to use new
faculty hires to improve diversity;



Commitment of NCA&T to connect the LSAMP they lead to the proposed ERC;



Commitment of industrial members to provide at least 50 student internships per
year;



Outreach collaboration with the
Minne
apolis Museum of Science
to provide
hands
-
on experiences;



K
-
12 collaboration with Project Lead the Way;



Commitment of the National Fluid Power Association (NFPA) to employ their
member network of 400 system integrators (distributors) to bring ERC innovatio
ns
to market;



Commitment of NFPA to fluid power education (charter requires investment of one
third of profits from annual Fluid Power Exposition to fluid power education)



Agreement of all 48 industrial members on a patent/licensing policy for the
proposed

ERC.


Weaknesses



Need to develop a formal strategy for recruiting underrepresented minority
students in the mainstream activities of the Center in addition to the proposed REU
mechanism.


Response
:
The mainstream activities of the ERC are the research pro
jects. Participants in these
research projects include graduate research students, undergraduate research students, and
faculty. The strategy for ensuring participation by underrepresented minority and women graduate
and undergraduate students in the rese
arch projects has two components: (1) recruiting, and (2)
retaining.


The means for recruiting underrepresented minority and women graduate students first involve
engaging those students in research projects as undergraduates
because
this has been shown t
o be
the single most important factor that motivates the decision to pursue graduate education, and is in
fact the very reason for implementing an REU program. Beyond the summer REU program,
undergraduate students will become involved in ERC research proje
cts during the academic year
through existing Undergraduate Research Opportunities Programs (UROPs), and independent, for
-
credit research courses. The ERC will seek supplemental NSF funds for engaging undergraduates
in research. The ERC summer industry int
ernship program offers additional opportunities for

9

undergraduates, particularly those who want industry experience, to work on fluid power projects.
Active recruiting of underrepresented minority and women undergraduate engineering students for
ERC resear
ch and internship opportunities will occur throughout the ERC network of core and
outreach institutions, taking particular advantage of the broader networking opportunities offered
by our LSAMP and AGEP partners, as well as taking advantage of recruiting o
pportunities

through existing programs for minority and women engineers at the core and outreach institutions
(e.g. the Purdue University Women in Engineering Program, in existence for 36 years
).


Recruiting

underrepresented minority and women
graduate

st
udents for ERC research assistant
positions will first take advantage of the pool of ERC undergraduate research students. The
recruiting will be across the network of institutions in the ERC
,

which broadens the numbers and
opportunities. Existing programs
for underrepresented minority and women students will assist in
recruiting efforts. The ERC will also recruit from beyond its own network of schools. Recruiting

strategy and recruiting visit activities will include the ERC Student Leadership Group (SLG)
b
ecause student
-
to
-
student recruiting can be more powerful than faculty
-
to
-
student or staff
-
to
-
student

efforts
. ERC funds will be allocated to the SLG for this activity.


The tentative goal for ERC graduate research assistants is 20% underrepresented minor
ities and
20% women. The detailed recruiting activities, schedule, and final targets will be set during ERC
strategic planning process.


Once recruited, an active mentoring and support
-
group program will be the primary strategy for
retaining underrepresen
ted minority and women graduate students

in the ERC research projects
.
Mentoring programs are critical for retaining minority and women students seeking engineering
degrees and for motivating these students to pursue academic and industr
ial

engineering car
eers. A
networking mentoring approach will be adopted, modeled after the successful Purdue Women in
Engineering mentoring programs for undergraduate and graduate students. Mentoring activities
will

be

integrate
d

into existing programs for ERC sites where s
uch programs are in place. A cross
-
site program will also be implemented for all ERC underrepresented minority and women students,
which
will take advantage of the breadth and numbers offered by the five core and two outreach
academic institutions, and by
the inter
-
site communications structure being implemented for ERC
management.



2.


Vision, Potential Impact


Review Criterion:



Proposal defines an emerging engineered system with strong potential to spawn new
industries, transform our current industrial
base, service delivery system or
infrastructure, and have a broad societal impact.


Fluid power is used in a wide range of industries, due to the high power density provided by this
actuation technology. The vision statement quoted from the proposal is as

follows:


The vision of the ERC is to create new fluid power technologies that are compact and efficient. This
will lead to significant fuel savings as the new technologies are implemented in existing and new
operations
.

The new operations will enable ap
plications and new products requiring portable high
-

10

power (non
-
centralized),

untethered

operations over long periods. As the vision of the ERC is
realized, both short term and long term advantages will accrue. Improved efficiency will greatly
reduce petrol
eum consumption and pollution
in our economy, recovering the C
enter’s cost many
times over. Improved compactness will enable fluid power to perform tasks that are not presently
possible, spawning whole new industries.


An alternative statement was provided

at the site visit:


The ERC will create new fluid power technology that is compact and efficient. This will cause a
radical transformation of fluid power, significantly reducing energy consumption and spawning
whole new industries. A coordinated research
and education program will facilitate this
transformation
.


The vision of the ERC is particularly well targeted and has been influenced by the leading fluid
power companies in North America. These targets include:



Improving energy efficiency in fluid power

by developing alternative circuit configurations
to eliminate the need for servo
-
valves (a major source of major energy loss);



Energy recovery through the design of compact and high density energy storage modules
(with potential application in the transpo
rtation industry);



Reduction of leakage and the development of cleaner systems;



Size and weight reduction of fluid power supply modules to enable construction of compact
and portable systems;



Improvement of the operator interface to enhance the usability o
f the technology.


To achieve these targets, new components and system configurations are required.


The projected deliverables of the project will indeed have a transformative impact on the fluid
power industry and open new market sectors if they are rea
lized. The proposal is very strongly
supported by the fluid power industry. Given this level of industrial involvement, a framework
exists for the commercial exploitation of research results leading to the potential creation of new
industries. The proposal

also targets the promotion of fluid power and education in line with the
requirements of industry for highly qualified persons and diversity.


The reviewers generally agree with the high impact potential of the proposed research; however, the
ability of
the team in achieving their targets has been debated and detailed in the following sections.


3.

Strategic Research Plan and Research Program




Strategic Plan Review Criteria:



Research plan targets critical systems goals, identifies challenging scientific an
d technical
barriers to be overcome
,

and proposes high quality research projects and proof
-
of
-
concept
test
-
beds to address these barriers;





Proposal demonstrates a clear knowledge of the state
-
of
-
the
-
art and presents a
persuasive
strategy for advancing it
.


The research plan identifies three main targets. The first two, efficiency and compactness, are of
first
-
order importance for the fluid power industry. The site visit team heard convincing arguments

11

from both research and industry perspectives to confi
rm this view. The research plans to address
these topics focus on developing throttle
-
less control (roughly analogous to switching control in
power electronics), the ability to regenerate power (again as commonly found in power electronics)
and the reducti
on of parasitic losses through improved seals, surfaces, etc. Particular scientific and
technical challenges include the modeling and development of actively controlled bearing and seal
surfaces, extremely fast digital valves capable of high pressure and f
low, and the development of
pumps and systems that permit recovery of power when actuators are “back driven” by loads. The
proposed projects should make important contributions in these areas.



A question was raised regarding the critical need of fast
-
swi
tching valves for high fluid power
paths. This question has been clarified by the proposers, who explained that extremely fast
-
switching valves are only needed in the PWM control of pump displacement in Project 1e, for
which a novel rotary valve concept
was shown. The other projects that involve improving
efficiency (e. g. projects 1a and 2a) do not require very fast
-
switching valves in the fluid power
path. Unthrottled on
-
off valves, instead of throttled proportional or servo valves, will be used in th
e
low
-
power path. Expertise in fast switching valves, including electromagnetics and power
electronics, will be drawn upon in the future if it is found necessary during the course of the
research.


The third target is a collection of goals to reduce chara
cteristic drawbacks associated with fluid
power equipment (noise, vibration, leakage) and address human factors issues. The problems of
noise, vibration, and leakage are widely acknowledged as precluding hydraulics and pneumatics in
many applications today
; although, by themselves, they would hardly justify an ERC program. The
topic of “human factors” could easily be a thrust area in its own right, but in the context of this
proposal it is focused on improving the dynamic human/machine interface for operati
ng fluid
powered equipment. Human/machine interaction is a critical research area and the specific
problems associated with interacting with fluid power are a worthwhile topic of investigation under
this ERC, with its strong controls expertise. There is s
ome question as to whether the broader
problem of human factors design, including the cognitive and psychophysical aspects of an
ergonomic interface, will be addressed. Nonetheless, if the proposed human factors work can clarify
what is unique about human/
machine interaction for fluid power (especially for the new class of
fluid power devices proposed under the first two target areas), as contrasted with electromagnetic
devices, this will be a useful contribution to the fluid power industry.


Response
:


We
agree that the broad topic of human factors could comprise a center in its own right, and hence
the scope
of human factors research in the ERC
must be limited in several respects. Fluid powered
systems provide our compass for research directions. If a pr
oblem or opportunity is not
emphasized or influential in fluid power systems
,

the priority of that
research

must be lowered,
although
application

of human factors principles and human centered design techniques, for
example, is still an imperative. Cognit
ive and psychophysical aspects will in some cases be
addressed as indicated by the above criteria and detailed under Thrust 3, subsection i.


F
luid actuation
is
different than electromagnetic actuation for haptic
s and other enhanced
interfaces.

In fluid p
ower, linearity has often been sacrificed for efficiency and vice versa. The root
cause is that
to be
effic
ient, hydraulic actuation systems must control
flow (velocity)

while

electromagnetic actuation systems can
control effort (
torque or force
)
. Pneuma
tic actuation, when

12

ap
plicable, can be structured as force control,

but the trapped volume of a compressible gas results
in lower bandwidth with light damping. In the innovations for efficiency an
d compactness proposed
in this C
enter, we expect drastic mo
difications of the dynamics will occur
that
are not yet fully
modeled. Appropriate c
oupling
of
these
unique
dynamics
of fluid power devices
to the capabilities
of human operators will be
the primary human factors research challenge for the ERC.


The proof
-
of
-
concept test beds span a diverse range of applications. Any one of the test beds has the
potential to take advantage of any of the research contributions described in the research plan and
multiple possible technology migration paths are shown in Fig.
1 of the proposal. Whether the test
beds actually do exploit and advance various research projects will depend on the management by
those who have primary responsibility for each test bed. (As an illustrative example, it is unclear
whether there are specif
ic plans to guide the development of the free
-
piston compressor to expedite
its incorporation into a legged crawler or into hand tools.)


Response
:
During the site visit
,
the

detailed
interrelationship between projects
and test beds
in the
three
-
plane diag
ram was explained.
The research projects are

highly
coupled and related to overall
C
enter goals. In the case of the sUV, the r
esearch involves

ten projects from

all three thrust areas,
nine principal investigators
,

and all seven academic institutions
. Some

of the projects provide

alternative methods of achieving the same goal. Depending on results

at any particular time
,
alternative
research
approaches might be
continued, or resources might be redirected toward more
promising approaches.


Major decisions on

research
project direction
s and test beds

will be
made as described in
the
management plan. This plan requires
an
annual
formal
evaluation of project results and future
plans
, and is guided by the

strategic
plan
. Decision making on a shorter time
-
scale
is

more informal
and
distributed, with responsibility for test

beds resting with the test bed leaders. A key
element that
ensures smooth integration of the enabling technology projects into the test bed development
projects is frequent communication that
pro
vides channels for continuous ongoing decision making
at all levels.


Plans exist
to incorporate
the free
-
piston engine

into the legged crawler and the
portable powered
hand tools test beds. The design and inclusion of the free
-
piston concept into each tes
t bed requires
careful design and development that matches the dynamics associated with the energy generation
and transduction of the specific configuration of the free
-
piston device chosen for each platform, to
the dynamic characteristics of the load, fol
lowing fundamental maximum power transfer
and
impedance matching arguments.
Design requirements needed
to incorporate the free
-
piston engine
into the legged crawler and the portable powered hand tools would come from the respective test
bed leaders work
ing

closely with the free
-
piston research project leader.


The proposal demonstrates a clear knowledge of the state of the art and presents a broad strategy for
advancing it.


The authors of the proposal appear to be well aware of the current state of the art

in the relevant
fields of fluid power, controls, human/machine interfaces and of the potential limitations of the
approaches they are proposing, as well as those of others.


Thrust Area Review Criteria
:


13



Proposing significant goals and targeting significan
t barriers;



Proposing high quality research methodologies that will advance the state of the art;



Integrating knowledge from other projects and thrusts needed to achieve the Thrust's goals;



Proposing a diverse research outreach team with the skills and dis
ciplines needed to
achieve the goals.


Thrust 1: Efficiency


i.

Throttle
-
less Control and Regeneration


Fluid power is widely used in applications that involve manipulation of heavy loads. There are two
elements in conventional fluid power systems that make t
his technology very energy inefficient as
follows:



A centralized supply module is used that maintain the hydraulic fluid at a high constant
pressure, typically in the range of 3000 to 5000 psi. To maintain this constant supply
pressure a pump continuously

runs irrespective of the state of operation of the system
actuated by the hydraulic system (for example in a hydraulic robot, the hydraulic pump
continuously operates even if the robot is stationary). This is wasted energy that is very
significant and can

be avoided by using more advanced pump control strategies.



Conventional fluid power systems use a servo valve that channels the high
-
pressure
hydraulic oil from the supply system to the hydraulic actuator (e.g. a piston). Changing the
size of the orifice
in the valve regulates the rate of flow in and out of the actuator. Orifice
flow results in hydraulic resistance and loss of pressure and energy.


There are a number of strategies and alternative circuit configurations that can be used to overcome
energy i
nefficiency. The choice and design of these alternatives is based on trades
-
off among
bandwidth (speed of response), accuracy, and energy consumption.


The center researchers have chosen to investigate two out of four possible alternative design
strategies
: hydrostatic actuation using a piston pump, and a throttle
-
less centralized supply that
avoids the use of a variable orifice servo
-
valve by using a high frequency bypass valve. These
configurations are more efficient, but not necessarily the best in term
s of energy efficiency. Their
choice is nonetheless justified, as they preserve or exceed the high operational bandwidth (speed of
response) of conventional systems.


The circuit configuration (i) presents an interesting applied research direction that cou
ld involve
multiple input pump
-
speed and swash
-
plate control for energy versus bandwidth trade
-
off.
Irrespective of the optimality of its design, it nonetheless presents a powerful alternative to the
present form used in hydraulic equipment. Evaluation of
this technology for industrial applications
is an essential element for its wider adoption in the fluid power industry.


The second (ii) circuit option is novel. It conceptually shares some challenges associated with load
sensing fluid power systems, nota
bly stability. The system dynamics, speed of the valve, and the
system level advanced control for stability are barriers that are critical to realizing this technology.


Response
:
Research project
s

1A and
1
E will develop
novel hardware components
and the
a
dvanced control strategies required for stable, high bandwidth operation.


14


This research module is very significant to achieving the aim of higher energy efficiency in fluid
power systems. It contains considerable research and follows a direction that is v
ery likely to
succeed. The project involves integration of advanced control with design and industrial
application. The Center researchers, namely Stelson, Alleyne, Li, and Ivantysynova, have well
established track records in this field and have collective
ly the expertise to achieve the objectives of
this module.



ii.

Elastohydrodynmic (EHD) Effects for Adaptive Surface Design


Due to component deficiencies, undesirable tribological effects are expected to occur in the pumps
and motors of the project. In the i
nterest of efficiency, it is essential to eliminate such effects and
this will be done by adaptive design of the bearing surfaces. Lubrication is in the EHD mode, thus
the individual contact areas are small and the proposed surface modification must be of
comparably
small scale. There are examples of passive surface modification in the literature (for example the
laser surface texturing, as advocated by tribologists in Israel and in the USA), but this appears to be
the first proposal for active surface cont
rol. To be successful at adaptive surface control it is
essential to start from a theoretical analysis, or at least a hypothesis, as to how the surfaces are to be
modified to achieve the desired result.


To achieve the goal of eliminating undesired tribol
ogical effects, it is proposed to “investigate thin
film flow and surface shape and roughness, … as this knowledge is needed to take advantage of
elastohydrodynamic effects in thin films. Surface contours are then to be changed either by (1)
piezoelectric

elements organized on a grid, and/or (2) pressure deflected membranes inserted into to
the surface.


A weakness of the proposal is that beyond listing the Reynolds Equation, it puts forth no hypothesis
as to how a surface should be changed in order to les
sen undesirable local pressure and/or friction
peaks. The only indication as to the proposers’ thinking on the subject comes from the ‘Responses
to Questions’ session: “Investigate the phenomena in high pressure thin films in nanoscale domain
to understan
d and model them, to know how pressure film develops, to quantify energy dissipation
in the gap.” It is not discussed if continuum theory is still applicable in gaps of nano
-
scale, with or
without slip, or if molecular dynamics, or perhaps some other metho
d is called for. There are
several references on this topic, some of them in the Journal of Tribology.


The team certainly has members, e.g. R. Salant of Georgia Tech, who are eminently suited to
perform the type of research needed here. However, the propo
sal did not devote sufficient time and
effort to discuss and evaluate this problem.


Response
:


T
he main source of energy dissipation in positive displacement pumps and motors
is
the lubricating
gaps between
moving
parts. The lubricating gap in positive
displacement machines fulfills a double
function; it
must
seal the displacemen
t chamber and simultaneously
transf
er high forces and
moments to fulfill its
bearing function. The design goal is to achieve a sufficient fluid film, which
generates the necessar
y load carrying ability with minimum energy loss due to friction and leakage
and allows avoiding any contact of surfaces. T
o reach this design goal of an optimal gap

require
s


15

adaptive surfaces because of varying operating parameters. The aim is to find met
h
ods for adaptive
surfaces that

allow effective reduction of friction and flow losses and optimal bearing and sealing
function of the gap in a wide range of operating parameters of the machine. This would allow a
drastic reduction of losses and improve of
efficiency of pumps and motors in partial load conditions
and a further increase of power density.


Basic gap heights are in a range of some microns, whereas all other dimensions are in order of
centimeters.
Therefore,
continuum mechanics can be applied f
or the proposed work. It has been
experimentally proven by gap pressure field measurements (Ivantysynova et al. 2005) that the
elasticity of machine parts lead to local gap height changes of usually less than one micron and that
these local gradients gener
ate elastohydrodynamic effects, which improve the load carrying ability
of the gap.


The hypothesis for the
proposed research is

that
gap heights

and resulting surface shapes

that
minimize loss while satisfying loading carrying and sealing requirements can

be determined by
using and modifying the multi
-
domain gap flow model implemented in CASPA
R (Huang and
Ivantysynova 2003) for
the entir
e range of operating parameters.
CASPAR uses a special numerical
method for an iterative coupling of

separate solvers for

the fluid/
solid domains. The Reynolds,
continuum and energy equation are used for the fluid domain, where the local changes of viscosity
with pressure and temperature are considered for each grid point of the fluid grid. The equation of
elasticity is used

for the solid domain and the gap heights are determined by solving the motion
equation of the multi
-
body system forming the connected lubricating gaps of the displacement
machine (Ivantysynova 2004).


It has been proven by experiment that very small chan
ges of surface shape (some microns) can
improve the load carrying ability of the gap and reduce energy dissipation
.

With a half barrel like
piston

a reduction of leakage of 60% and 15% reduction of friction has been achieved

(Lasaar and
Ivantysynova, 2004)
. The problem of a fixed shaped surface is that the design can be optimal only
for a predefined combination of operating parameters (speed, pressure and displacement ratio).


Comparing simulation results with measurements (leakage, gap temperature distribu
tion and
pressure field measurements) on a real machine have clearly shown that local surface deformation
of less than 1 micron lead to significant changes of gap flow conditions and a large impact on
energy dissipation in the gap (Ivantysynova and Huang
,
2005). This explains why

it should be
possible to achieve optimal gap heights by combining different methods of passive and active
surface design. Methods for active surface design will be studied in project 1C. The theoretical
work in 1B will be combined
by experimental investigations using and modifying existing special
test rigs. These test rigs allow also studying the influence of surface roughness on the gap flow,
which is not considered in the current CASPAR model
, and will be done in

close co
-
operati
on with
project 1D (micro
-
texturin
g of surfaces)
.


Ivantysynova, M. and Lasaar, R.

2004.
An investigation into Micro
-

and macro geometric design of
piston/cylinder assembly of swash plate machines. Intern
a
tional Journal of Fluid Power.
Inte
r
national Journ
al of Fluid Power, Vol. 5 (2004), No. 1, pp. 23
-

36
.




Huang, C. and Ivantysynova, M. 2003. A new approach to predict the load carr
y
ing abi
l
ity of the
gap between valve plate and cylinder block. Bath Workshop on Power transmission and Motion
Control P
TMC 2003, Bath, UK, pp. 225


239. Best p
a
per award.


16


Ivantysynova, M. 2004. EHD
-
based simulation model for connected tribosystems of displacemnt
machines. (in German). Tribologie und Schmierungstechnik. Vol. 5 (2004), No 5, pp. 18
-

24.


Ivantysynova, M.,

Huang, C. and Behr, R. 2005. Measurements of elastohydr
o
dynamic pressure
field in the gap between piston and cylinder. Bath Workshop on Power Transmission and Motion
Control PTMC 2005, Bath, UK, pp. 451


465. Best paper award.


Ivantysynova, M. and C. H
uang, 2005. Thermal Analysis in Axial Pi
s
ton Machines using CASPAR.
Proc. of the Sixth International Conference on Fluid Power Transmission and Control, Hangzhou,
China



iii.

Micro
-
Actuators for Active Surface Modification


The proposed research to adjust annu
lar gaps between the sliding surfaces using piezoelectric
surface coatings is questionable. More fundamentally, the proposed research focused on controlling
0.5 to 1 micron gaps (based on modeling and simulation) without recognizing the dimensional
variati
ons due to manufacturing and assembly tolerances (tolerance stack
-
up), which might exceed
1 micron. The hypothesis is that the control of 0.5 to 1 micron gap is essential to improve load
bearing and lubrication properties that, in turn, influence the energ
y efficiency. Although an
alternate method was briefly presented during Q&A session, this method suffers from similar
shortcomings to the piezo approach, leaving the impression that the project as a whole is poorly
conceived. Furthermore, there seems to b
e disconnect between theoretical models and simulations
and the physical reality.


Response
:

While the reviewers are

correct that the required surface adjustment lies in the range of
typical ma
nufacturing tolerances of parts,
it is the
surface
height spat
ial variation

that
determines

the

local
pressure distribution. On the othe
r hand
, manufacturing
variations are generally of much
lower spatial variation. For instance, t
he tolerance of the piston diameter is usually 2 micron and
the required flatness of th
e valve plate is 0.5 micron. The spacing of the actuators in our proposed
design is 2 mm, but the diameter of a valve plate is 70 mm. A 1 micron difference over 2 mm.
creates a larger slope than a 0.5 micron difference over 70 mm.

Thu
s, actuators for surfa
ce
adaptation can easily provide sufficient actuation
to compensate for the effect of

manufacturing
variations.



We are not proposing to control the entire gap height between movable and highly loaded surfaces.
The gaps in positive displacement machines a
re self adjusting. The local gap height is a complex
function resulting from surface design, micro
-
motion of parts, operating parameters, material
stiffness and fluid properties. The gap heights are between 2 and 10 micron. It has been proven by
experimen
t that
local

gap height changes of several hundreds of nanometer up to 1 micron can
improve the load carrying ability of the gap and reduce energy dissipation in the gap.
(
Ivantysynova, et al.

2005
) and (
Ivantysynova, M. and C.

Huang, 2005
)
.


We
will

inves
tigate the use of different micro
-
actuator technologies to actively change the surface
shape. The required range of adjustment lies between 0.2 and 1 micron and is limited for very small
areas of several square millimeters. This will allow to adapt the sur
face shape to varying operating
parameters and to improve efficiency in the entire range of operating parameters. It has to be
pointed out that the required deflections (local change of surface shape) are not steady state, but

17

the magnitude of deflections

has to change with basic pump frequency, given by pump speed and
double number of displacement elements, i.e. frequency range of kHz.


Piezo
-
actuators are one approach that will be investigated.
P
iezo materials typically have an
operating strain of around

0.1%. Thus,

a 1
micron
displacement can be obtained from a 1 mm thick
layer, a feasible thickness to deposit using screen printing.

Order of magnitude motion
amplification
can be obtained via well known

techniques.


Several
other questions

in regard to p
iezo
-
actuators
have been

asked

in previous stages of the
review process. These include

questions about hysteresis, temperature effect and

power
consumption. Recent control approaches allow hysteresis to be routinely controlled in piezo
systems. The ferroel
ectric effect due to temperature changes can be compensated with a well
-
know
reference component circuit approach with little loss of performance. Power consumption of the
piezoelectric elements would be a few mil
liwatts when operated in the required

frequ
ency range
and would have a negligible influence on efficiency or operating temperature.


Other approaches to gap manipulation that could be considered include elements that are deflected
by pressure, temperature
or

electrostatic forces.


Ivantysynova, M
., Huang, C
. and Behr, R. 2005. Measurements of elastohydr
o
dynamic pressure
field in the gap between piston and cylinder. Bath Workshop on Power Transmission and Motion
Control PTM
C 2005, Bath, UK, pp. 451


465.

Best paper award
.


Ivantysynova, M. and C.

Huang, 2005. Thermal Analysis in Axial Pi
s
ton Machines using CASPAR.
Proc. of the Sixth International Conference on Fluid Power Transmission and Control, Hangzhou,
China
.



iv.

Biomimetic Nano
-
Surfaces


In the interest of efficiency of design, it is essential

to reduce flow drag in fluid power systems. In
order to achieve the desired reduction of energy consumption in hydraulic systems, it is essential to
drastically reduce flow drag in the conduits. The flow in the conduits is mostly laminar, however,
and in
laminar flow we have very few methods for drag reduction. The proposal recommends two
methods, nano
-
surface structuring and introducing a micro
-
bubble surface between the wall and the
fluid. In laboratory trials both methods seem to work, though they are f
ar from ready for large
-
scale
application.


If nano
-
texturing is coupled with rendering the surface hydrophobic, the fluid glides over the
valleys between posts almost frictionless on air bridges, experiencing ‘real’ friction only over the
hydrophobic pos
ts. Even greater reduction in drag, up to 95%, is possible by allowing the fluid to
slip on the micro
-
bubble surface. In hydraulic machinery, the pressure in the conduits is usually
large; the proposal does not mention a possible pressure
-
level limitation
to either method of friction
control. It is supposed that this was thought of by the authors of the proposal and will be researched
at some later stage


Response
:

The reviewers correctly point out critical issues associated with drag reduction in that
emb
edded gas bubbles are used to obtain drag reduction but application can not be immediate to

18

fluid power systems since these techniques have only been tested on a) rigid surfaces with b)
moderate pressures and c) simple laboratory geometries.




The

issue

o
f

pressure

variation

is

complex

in

that

any

gas

bubbles

will

expand

or

contract

which

can

effect

the

overall

drag

reduction.

This

may

be

addressed

by

using

conical

pits

(instead

of

grooves

or

cylindrical

pits)

so

that

changes

in

bubble

volume

have

a

lower

impact

on

changes

in

the

gas
-
liquid

interface

position.

Research

will

be

needed

to

assess

the

sensitivity

of

drag

reduction

to

pressure

variations

for

different

texturing

but

it

is

expected

that

systems

with

moderate

pressures

will

be

more

tolerant

of

su
ch

variations.

Another

research

issue

which

will

be

addresses

is

that

of

flexible

surfaces

associated

with

fluid

power

lines.

In

this

case,

care

will

be

needed

in

that

surface

micro
-
structures

can

be

altered

by

any

tube

bending.

Experimental

testing

wil
l

be

conducted

for

various

micro
-

or

nano
-
texture

surface

geometries

and

materials

to

understand

(and

control)

the

relationship

between

overall

drag

reduction

and

tube

curvature.




The introduction of micro
-

or nano
-
structured surfaces onto polymers is a
n emerging large volume
commercially successful technology. Current microstructured products with sales in excess of $10
billion per year include diverse applications such as: retroreflective products with three
dimensional corner cube structures, brightne
ss enhancement film in LCD displays (e.g. laptop
computers, cell phones) with linear structures, adhesives with controlled surface tack and air bleed
channels, and abrasives with controlled three dimensional cutting structures. Both thermoplastic
and therm
oset polymers are used in these product applications. While these current applications
are largely film or flat formats, the technologies have the potential of being applied to other
geometries such as pipes and tubes. Global large scale manufacturing infr
astructure is in place to
support current products and is an area of continued significant investment. Furthermore, there is
substantial interest in new high value growth opportunities leveraging existing technologies.


The

emphasis

for

development

of

drag

reduction

concepts

will

be

for

small
-
scale

(human
-
scale)

fluid
-
power

systems

like

the

orthotic

device,

crawler

and

hand
-
tool

test

beds,

whereby

friction

line

losses

are

more

severe

since

these

require

considerable

compactness

and

the

surface
-
to
-
volume

rat
ios

become

much

larger.

For

example,

preliminary

calculations

with

the

orthotic

device

indicate

that

conventional

fluid

power

line

losses

would

be

responsible

for

as

much

as

10
-
20%

of

the

power

(whereas

losses

on

the

order

of

1
-
3%

are

more

typical

for

lar
ge
-
scale

systems

like

the

excavator).

Also,

the

small
-
scale

devices

tend

to

be

more

expensive

in

terms

of

cost/weight

ratio

and

therefore

are

more

attractive

to

insertion

of

new

technology

(which

can

later

trickle

into

larger

systems

as

the

technology

b
ecomes

more

robust

and

simpler

to

manufacture).

Finally

small
-
scale

devices,

tend

to

have

lower

pressure

variations

which

reduces

sensitiv
ity

to

gas
-
liquid

interface

vari
ations.


v.

On
-
Off Valving Concepts for Throttle
-
Less Control


The On/Off PWM rotary val
ve concept has the potential to significantly reduce energy consumption
by eliminating the servo valve. The proposed design would have lighter weight, less complexity,
and would be less expensive. Many of the leakage and friction losses encountered with
traditional
pumps could be reduced with this concept.


While a complete description of the concept was not disclosed to the panel due to patent issues, the
main idea was. The rotary design presented could have some of the same problems that
conventional p
umps have. That is, the losses that would be present due to friction and leakage, and
potential issues with contamination. In addition, the high frequency pulsations at high flow rates

19

will create significant noise that will be difficult to suppress. Fi
nally, non
-
instantaneous switching
times will create some throttling losses. These effects would constitute research to be conducted by
the proposed ERC.


This project integrates with the knowledge base of the other projects, and directly addresses the
ma
in goals of the Center for efficiency and compactness.


Response
:

The on
-
off valve
project represents one of several possible avenues to achieve throttle
-
less control of hydraulic circuits. By integrating new hardware and control design (m
echatronics),
per
formance

and compactness beyond currently available variable displacement machines will be
a
chieved
. This project will benefit from the synergistic activities in other research projects within
t
he ERC (e.g. 1B/C, 3D)

to resolve
the friction and leakage iss
ues.
Also, pulsation induced noise
and energy loss will be significantly lowered if the system can be more tightly and compactly
integrated. The latter will be enabled by the systematic integration/optimization approach to be
developed in Project 2E.
A

hig
h speed on/off valve is an important enabling element for this project.
A promising valve design concept that can circumvent the traditional tradeoff between performance
and power input is currently being deve
loped
. While friction and leakage are important
, results
from our experimental prototype suggest they are not prohibitive.


vi.

Biomimetic Approaches to Distributed Fluid Handling


The proposal borrows from animal biology by proposing peristaltic pumps for fluid handling. In
contrast to conventional pumpin
g, where pumping of the fluid is done centrally, peristaltic pumping
is performed by the walls of a flexible conduit. Such pumps have been in use for pumping blood for
several decades and MEMS
-
scale versions are recently proposed for drug delivery. Often t
he walls
are moved magnetically. Precise control of timing is essential.


Peristaltic pumps seem to perform well in the laboratory, and they appear to be well suited for parts
of this project. However, the proposal contains no analysis of power requirement

versus flow rate,
pressure magnitudes that can be achieved, if scale
-
up has been attempted, or if it is at all possible.


The proposed network of MEMS
-
scale pump
-
valve devices is unrealistic. The most advanced
MEMS actuators generate somewhere between 0.
5 to 1 milli
-
Newton. Force required in a typical
peristaltic pump (say a palm
-
sized) will be several orders higher


10 to 30 Newtons. The authors
state, “by having many pump
-
valve devices, the total power is the sum of the powers of each
device.” This req
uires hundreds of thousands of MEMS
-
scale devices that need to be coordinated
and is hence unrealistic, at best. The authors propose to carry out a detailed analysis, simulation and
testing, to identify an appropriate application. This suggests that the de
cision to use MEMS scale
devices is already made and the effort is to find a fluid power application. A thorough evaluation of
the research objective should be carried out. The motivation for a new type of peristaltic pumps
(beyond what is already availabl
e today) and an appropriate means (likely non
-
MEMS) to
accomplish the same must be established before the project matures into detailed analysis,
simulation and testing.


Response
:

D
istributed fluid handling will be a significant scientific and engineering

challenge.
The target appl
ication for this project is
human
-
scale fluid power systems such as the
orthoses/prosthesis. These systems require relatively low power compared to some of the more
conventional fluid power systems. Joint power requirements du
ring walking

indicate that ankle

20

power
peak
s

at 450 W during normal adult walking while knee power peaks at 200 W. For TB
-
6,
one focus will be on gait stabilization rather than
full powered gait. F
or a knee
-
ankle
-
foot orthosis,
assuming a 10% assistive i
nput power input, the power needed is in the range of 60 W.


While the power requirement is lower than other applications of fluid power, the constraints are
more severe. In these systems, key factors to human acceptance include noise and vibration, as wi
ll
be studied in Thrust 3, in addition to efficiency and compactness from Thrust 1 and 2. Essentially,
in addition to being efficient and compact, the power generation must be silent and produce no
vibration. To aid in efficiency, the general goals of th
is project are to move the power generation
closer to the actuation sources distributed throughout a fluid power system. This is in contrast to
conventional fluid power systems that generate power centrally and then distribute it over long
lines to the ac
tuation point. This will minimize pressure losses in the conduits which will be higher
in these systems given the flow conditions. In order to minimize noise and vibration, a peristaltic
device is used to provide positive displacement flow control. Any
type of reciprocating pumping
device, involving mass acceleration and deceleration, would introduce unwanted vibrations making
it unacceptable to the user. The ideas of distributed pumping and low
-
ripple flow control are taken
from biological examples, he
nce the use of “Biomimetic Approaches” in the project title
. The key
notions that make this project biomimetic are the distribution of power generation, sensing, flow
control, and actuation.

mono
-
propellant

-
valves
flex lines

-
valves
actuator
peristaltic
pump
pumping
catalyst
mono
-
propellant

-
valves
flex lines

-
valves
actuator
peristaltic
pump
pumping
catalyst

An initial concept distribution is shown above. This is one of

several concepts that will be
investigated during this project and a key initial step will be a broad, systems
-
level approach to
identifying solution concepts.
MEMS devices
are limited and cannot provide
high power pumping
action. However, we envision th
e use of both micro and meso
-
scale units for fluid distribution and
pumping, respectively. As sh
own in the schematic above,
microscale devices can be used for
metering monopropellant through catalyst packs

to provide power for

pumping through the meso
-
sca
le peristaltic systems. Currently available compact medical peristaltic pumps can achieve fluid
pressures of 0.5 MPa and flow rates of 250 ml/min, running at relatively low speeds, giving power
ratings of approximately 2 W per pump (www.gilson.com). Alth
ough multiple distributed valve
-
pumps can increase the overall power produced,
if we use current off
-
the
-
shelf components,
this is
still 0.5 to 1 order of magnitude below the
power needed for the orthosis. This

motivates significant
fundamental and applied

research
in meso
-
scale peristaltic pumps
to achieve the stated fl
uid power
goal. We
believe this goal is achievable
given the expertise within the C
enter.
T
he input power to
the pumps can be increased to approximately 20 W
using
chemo
-
fluidic vane motor
s instead of
electromechanical motors
.


The use of distributed valves
-
pumps and flexible tubing has advantages over other means of
actuation, which, if applied correctly, may reduce total power requirement thereby increasing

21

efficiency. The flexible tubin
g can also be used as an actuator not just a fluid distribution device.
By pressurizing a section of tubing we can apply a force/torque causing it to straighten. This would
improve compactness by eliminating the need for a separate actuator to convert th
e fluid power to
mechanical power. Also, the flexibility of the hoses can be used to store energy thereby eliminating
the need for a separate accumulator. For a walking example, a portion of the stride energy could
be stored in the elastic walls in a rege
nerative fashion and then injected back into the gait at the
appropriate moment.
T
he Center
has expertise in the use of such energy storage capabilities for
gait assistance.


Thrust 2: Compactness


i.

Chemofluid Hydraulic Actuators


The r
esearch on chemoflui
dic actuators is aimed at developing actuators directly driven by an
energy source from thermochemical reactions. The researcher, who has demonstrated quality of
previous research experience and familiarity with the current state of the art in the field,
will
develop lightweight and compact power supplies and actuators for use in human assistive devices.
The strength of the research is the ability to develop and enable technology for the design and
prototype fabrication of the actuators. The actuators are

particularly suited for integration into the
fluid power
-
assisted orthoses and hand tool test beds, and maybe the compact rescue crawler, but
are not useful for general high power industrial applications represented by other test beds.
Fundamental contri
butions include high bandwidth control of the actuator and knowledge in
compositions of the chemofluids under thermomechanical constraints. The efficiency of the
actuator is postulated to be high in the proposed design, which controls the actuation by met
ering
the chemical fuel line without using control valves in the high pressure and flow path.


ii.

Free
-
Piston Engine Compressor


The Free
-
Piston Engine Compressor research aims to provide a compact fluid power generation
source suitable for portable equipment

such as the proposed hand tools (TB
-
5) and crawler (TB
-
4)
test beds. Free
-
piston engines as sources of hydraulic power have been under investigation for years
but have never gained wide acceptance, due largely to some of the problems that the investigator
s
address in the proposal. The research team proposes to use compressed gas to eliminate the intake
stroke and the attendant problems with mixture control and compression. The basic approach is
interesting and could result in a compact, low
-
noise power sou
rce. The challenges in achieving
stable, reliable low
-
emissions engine control cannot be underestimated
--

as a very large body of
ongoing research on HCCI and compressed gas engine control makes clear. The research team is
not wedded to the traditional fr
ee
-
piston design and is also considering “semi
-
free” designs with an
elastic diaphragm, etc. The focus of this work should be on achieving compact fluid power
generation from a spark
-
ignited fuel, while minimizing the number of moving parts and noise. The
ERC team can avail itself of a large body of ongoing work (including other work at the member
institutions) on spark ignition combustion control in pursuing this goal.


The application of a compact spark
-
ignition fluid power source to hand tools and small
robotic test
beds will be greatly enhanced if those applications are considered from the outside in designing the
prototype power sources and if early working “bench
-
top” platforms are tested with the specific
power demand curves of those applications in m
ind. This level in interaction is not spelled out in

22

the proposal but it will help if the team responsible for the compressor is also partly responsible for
the crawler, as seems to be the case.


The fluid power industry stands to benefits from the results

of this work and has demonstrated that
its unique supplier/customer integration network is well positioned to bring such novel devices to
the marketplace and ensure their adoption by industrial customers.


Response
:

In addition to the goal of achieving co
mpact fluid power generation from a spark
-
ignited fuel with the fewest number of moving parts and low noise generation, it is also a cen
tral
goal to provide on
-
demand

start and stop of the engine for purposes of efficiency (no idle) and
inclusion as an eas
ily regulated source of fluid power for untethered fluid
-
power applications such
as the compact rescue crawler and portable hand
-
tools. Therefore, the configurations planned to be
pursued do not operate on a traditional engine cycle that is geometrically
l
inked to the engine
position. Running

such an engine and starting and stopping such an engine will be equivalent by
controllably injecting compressed gas and compressed fuel, such as propane, to eliminate the intake
and compression strokes or phases of eit
her a traditional 2 or 4 stroke engine. With regard to low
-
emission engine control,
Kittelson (UM) is an expert in energy conversion and the production and
use of alternative fuels, measurement and control of spark ignition engine knock, electronic engine
control, and the dynamics of diesel exhaust and other carbonaceous aerosols. He has also done
work on small scale free piston HCCI engines (re
f below). Such engines operate

w
ithout an
ignition system can
use
compressed
air for starting. Dr. Kittelson’s
e
xpertise will ensure that issues
regarding reliable low
-
emission engine control are incorporated in the design phase of the engine.


The free
-
piston compressor will be designed for the projected power requirements of the compact
rescue crawler. Prior work
by the PI (Barth) regarding pneumatic actuation will be drawn upon to
estimate the peak and average pressure and flowrate requirements of the crawler.
A separate
compact spark
-
ignition or HCCI fluid power source solution will also be pursued for applicatio
n to
the application domain of portable hand tools. The design of the proposed power sources will be
carefully matched to the intended load in the case of each application domain.


References

Aichlmayr, H. T. Kittelson, D. B. and Zachariah, M. R., 2003 "Mi
cro
-
HCCI Combustion:
Experimental Characterization and Development of a Detailed Chemical Kinetic Model with
Coupled Piston Motion" Combustion and Flame Vol. 135, No. 3, pp. 227
-
248, 2003.

Aichlmayr, H. T., D. B. Kittelson, and M. R. Zachariah. 2002. "Min
iature Free
-
Piston
Homogeneous Charge Compression Ignition Engine
-
Compressor Concept
-
Part I: Performance
Estimation and Design Considerations Unique to Small Dimensions," Chemical Engineering
Science Vol. 57 No 19, pp. 4161
-
4171

Aichlmayr, H. T., D. B. Kit
telson, and M. R. Zachariah, 2002. "Miniature Free
-
Piston
Homogeneous Charge Compression Ignition Engine
-
Compressor Concept
-
Part II: Modeling HCCI
Combustion in Small
-
Scales with Detailed Homogeneous Gas Phase Chemical Kinetics," Chemical
Engineering Scien
ce Vol. 57 No. 19 pp. 4173
-
4186

Aichlmayr, H. T., D. B. Kittelson M. R. Zachariah, 2001 “Micro
-
Homogeneous Charge
Compression Ignition (HCCI) Combustion: Investigations Employing Detailed Chemical Kinetic
Modeling and Experiments,” proceedings of Eastern
States Combustion Institute, 2001.


23


iii.

Compact Energy Storage


Energy regeneration is an area for improving efficient operation of hydraulic systems and, hence, to
reduce fuel consumption for a given task. The basic challenge is to increase the stored energ
y
density and reduce the volume required for the accumulator
-

such problems exist with the Eaton
HLA system for large trucks. Furthermore, higher energy density means higher pressures and along
with it comes safety concerns. The regenerative energy rec
overy, its storage and re
-
use have been
shown to improve the operational efficiency of excavators by up to 30% in many cyclic tasks. There
are real opportunities in this area. There are also few recent very good patents [i.e. Bruin et.al., also
called “Ec
omate” system, cylinder
-
in
-
cylinder energy storage concept, reduce the size of required
accumulator component. Technical papers by Wendel et.al. 2002 are also very relevant since he
directly deals with regenerative energy in excavators and valve eliminati
on concepts]. The small
urban vehicle test bed is an excellent idea. The gas
-
sorption concept is very intriguing. The open
accumulator concept, which can increase the energy density by a factor of 12 compared to Eaton
HLA system, is also very promising
. This is a very important topic and one of the central interests
of the industrial partners. Research projects in this area should be encouraged.


iv.

High Pressure, Lightweight Components


One of the ways in which the ERC will address the problem of maki
ng hydraulic equipment lighter
and more compact is to utilize custom
-
engineered components with high specific strength and
optimized geometry and internal structure. Advances in these fundamental areas of materials
science and mechanical design are relevan
t to many application areas in aerospace, energy
conversion, etc. The particular motivation in fluid power is to permit higher working pressures and
loads and to reduce the overall package size.


The team includes investigators who are familiar with compos
ite materials design and analysis
generally, albeit mainly in other application areas, and investigators with expertise generally in
rapid prototyping. The demonstrated work includes the design of custom
-
designed vacuum
-
cast
metal components in which the i
nternal structure has been optimized to reduce weight while
maintaining adequate stiffness and strength. The extension of these rapid prototyping methods to
metal matrix composites is suggested but the intended approach is not made clear.


Other parts suc
h as accumulators and storage devices are good candidates for high
-
strength fiber
reinforced composites. These materials are already widely used for pressure storage vessels. The
application of fiber reinforced polymers and ceramics to other elements of hy
draulic systems is less
developed but has potential for improving the compactness and efficiency of systems. There is a
potential for the ERC to make significant advances in this area. This work will need close
cooperation with the work in area (v) on
Comp
onent Integration

to have a significant impact on
pump and actuator design. The application of non
-
homogenous, fiber
-
reinforced materials to
complex three
-
dimensional components that experience high dynamic forces is a large research
problem in its own rig
ht and fluid power devices are just one application. The ERC team may need
to avail itself of external expertise in creating complex three
-
dimensional prototypes with very high
specific strength and stiffness.


The fluid power industry stands to benefit f
rom the results of this work, as do the aerospace and
automotive industries (e.g. for applications such as automatic transmissions).


24


Response
:

The use of solid free
-
form (SFF) fabrication as a rapid manufacturing process of fluid
power components will pr
ovide significant opportunities to change the way in which fluid
-
power
components are designed.


Due to manufacturing constraints, fluid power components are often
designed with fluid channel geometries that are far from optimal, e.g. straight channels con
nect at
sharp angles to accommodate traditional drilling processes.


The structure o
f the component is
often

determined by the manufacturing constraints. Through SFF, the design emphasis can be
transferred from meeting manufacturing constraints to satisfyi
ng the primary functionality


e.g.
fluid channels can be optimized for minimal flow resistance, and the geometry of the housing can be
optimized to reduce mass while maintaining structural integrity.


To achieve this, current methods
for topology optimiza
tion will need to be enhanced to allow for anisotropic material structures and
for tight coupling between structural and functional requirements.


To create metal matrix composite (MMC) objects, ranging from simple to complex in form, several
existing and

emerging processes will be used by the Center.


Mil
waukee School of Engineering is
doing research on a new hybrid process, CMP
-
Hybrid, to create prototype and end
-
use MMC’s,
targeting reduced cost and improved performance via simplified processing
(http:/
/www.rpc.msoe.edu/research/index.php).


It is anticipated

that CMP
-
Hybrid will become the
preferred method for MMC production within five years mainly do to simplicity and low cost.
Other techniques to produce functionally graded materials with high stren
gth and stiffness will also
be considered. For example, Metal Matrix Cast Composites (MMCC), LLC in Waltham, MA, has
developed three processes for creating complex MMC objects.


Much of their work uses a hybrid
approach, combining additive processes, such

as rapid prototyping, with pressure assisted
infiltration techniques.


The three techniques available are described by MMCC including:


1)
APIC (pressure infiltration), 2) TLM (tool
-
less casting process), and 3) 3DP (ceramic performing).


The Center will
use these new and emerging hybrid processes to improve performance, reduce
mass, and reduce volume via MMC's. We will avail ourselves of external expertise as needed to
achieve these goals.


v.

Component Integration


This project proposes the use of a new en
gineering methodology, which is used in other fields, in
the design and analysis of hydraulic systems. It leverages from other technologies of integrated
design in “virtual” modeling. It proposes an integrated model based and simulations to better
enginee
r such systems. The crawler test bed is only an example of how this approach can be used
to design compact legs etc, but no description of how this approach may have a generic value to be
applied to other components and systems of hydraulics. The use of
integrated digital, virtual,
simulation based design might give the engineers better tools, hence lead to better design of fluid
power systems and components. It should also be pointed out that industry is already using most of
these tools to some extent.

It is interesting to bring all aspects of the fluid power design under one
integrated design environment, that is to include the mechanical, control, CFD, thermal etc. issues
in one “virtual model”.


Response:

As pointed out by the review panel, the bui
lding blocks for the proposed research in
“virtual engineering” already exist and are often used in industry. In the current state of the art,
individual physical phenomena can be simulated (e.g., Computational Fluid Dynamics, or
Structural Analysis), but

capabilities for multi
-
physics simulation are lacking. Similarly, analysis
can be performed at the micro
-
scale (e.g., for tribological phenomena) or at the macro
-
level scale

25

(e.g., for system
-
level simulation of a backhoe), but tools for investigating in
teractions between
these multiple scales are missing. In our effort to achieve compactness, we anticipate that multi
-
scale and multi
-
physics simulations will be necessary to adequately predict the performance of such
strongly coupled, compact, integrated
systems. The main challenge in this project is thus to
integrate multi
-
scale, multi
-
physics simulations in an efficient and effective fashion, and to use the
analysis results to support the development of robust design solutions.


Achieving this goal will

have an impact not only in the development of the crawler test bed, but on
fluid power systems in general. By integrating all aspects of fluid power design into one "virtual
model" for optimization
-
based design, this project will provide our large suppor
ting industrial base
with tools that can give a near term jump in their system design. As designers push the envelope in
the cost
-
performance
-
reliability space, more design alternatives need to be evaluated more quickly
and at a more detailed level. This

requires significant innovation in simulation and design
environments. In addition, multi
-
scale, multi
-
physics problems are becoming increasingly common
in a variety of application domains other than fluid power (e.g., integrated electronic circuits) suc
h
that advances in modeling and simulation of compact integrated systems could have a much
broader impact.


vi.

Dynamically Scalable Fluid Power Systems


This module is an example of basic research proposed by the Center. It involves establishing
functional re
lationships between design parameters and relating these to system performance. It is a
theoretically challenging research topic that involves:



Scaling and mapping of the design parameters;



Analysis of best practices in design of industrial fluid power sys
tems and grouping of these
parameters into dependent clusters;



Establishing simplified functional relationships between design parameters; and



Creating component designs by taking into consideration the functional relationships.


The basic research concept
s investigated in this module are of high quality and are significant
beyond the requirements of the Center. There are substantive barriers in the development of this
theory for its specific application to nonlinear fluid power systems. These include the p
roblem of
functional discontinuity due to static friction and saturation effects. These challenges have been
identified and are within the scope of research.


The theoretical and data driven design analysis associated with this module is likely to confin
e its
use for the design of simple components within the first phase of the project. The center researcher
involved with this module has considered this concept for systems described by linear functions. He
is well qualified for this module.


Thrust 3: Noi
se, Vibration, Leakage, Contamination and Human Factors


i.

Human Factors and Haptic Interfaces


Human/machine interaction is itself an important research area, especially if we take the stated goal
to “…uncover the underlying principles behind the design of
effective human interfaces...” at face
value. However, it seems more likely that the project will focus on the specific problems associated

26

with humans interacting with fluid power, and these are a worthwhile topic of investigation under
this ERC with its

strong controls expertise. These problems come to the forefront for certain classes
of fluid powered devices, of which the powered orthosis (TB
-
6) and the excavator (TB
-
1) and
perhaps hand tools (TB
-
5) are primary examples.


There is some question as to h
ow the broader problem of human factors design for the test beds,
including the cognitive and psychophysical aspects of an ergonomic interface, will be addressed.
The test bed involving powered power hand tools (TB
-
5) provides a good example of the need to

augment the controls interface with general considerations of ergonomics, safety, comfort, etc. Most
questions about these topics were addressed to the partnership with NCAT.


Nonetheless, if the proposed human factors work can clarify what is unique abo
ut
human/machine
interaction for fluid power

(and especially for the new class of compact and efficient fluid power
devices proposed under the first two target areas) this will be a useful contribution to the fluid
power industry and to the general underst
anding of human/machine interaction when large amounts
of specific power are involved at machine end. It would be valuable to see specific plans, as the
ERC progresses, to investigate the ramifications of energy recovery and throttle
-
less control for the
h
uman/machine interface. How do these advances in fluid power control change the way in which
we think about the human/machine interaction for fluid powered devices such as tools, orthoses,
etc.? Does the human become a partner in the overall strategy to re
duce energy consumption? Is this
done at the expense of the robustness of the system stability? The team working on this topic
includes leaders from the controls and human/machine interaction area as well as from the throttle
-
less fluid power control thrus
t, which suggests that these interesting questions will be addressed
early on. These individuals are well aware of the current state of the art and should be able to isolate
the particular problems posed by fluid power for their focus of attention.


The li
nkage to the other human factors work at NCAT is less clear. If utilized effectively it has the
potential to enhance the user acceptance of the new class of fluid power products being proposed
for the test beds.


The research description of activities to b
e pursued related to human factors and haptic interfaces
are not at the frontiers of research in the field of research in the area of human factors and
ergonomics; however, the research effort lies in answering specific research questions related to the
ap
plication of key principles in the development of system interface and control designs that enable
users/operators of systems controlled by fluid power to properly and safely perform task operations.
It is a fundamental underlying hypothesis that by chang
ing the power control source of systems
through the use of fluid power, the dynamics of human control will change as well. If this
fundamental hypothesis is true, then the research activities proposed are greatly needed to ensure
operator safety and perfo
rmance. Specifically, the proposal plans to address issues associated with
interface design, which as written appears limited in scope and does not address the comprehensive
issues associated with User Centered Design approaches. By focusing on just the i
nterface design
issues, some of the underlying problems associated with human use of complex systems are ignored
and thus errors, inefficiencies, redundancies, operator frustration, accidents, and poor performance
may still occur.


Thus, a comprehensive re
search approach of analyzing the system design and control within the
framework of user centered design principles is strongly recommended. Also, the rationale of
focusing on “haptic” interface design aspects is not clearly stated in the proposal. There

are other

27

modalities of information input that have been proven to provide good informational cues to
human’s operating complex systems. Certainly, haptics is an important factor related to the test
-
bed
applications proposed; however, the research effort
s should be broadened to consider other
options/modes of providing operator feedback during task performance and execution, as well.

The specific research methods to be used in conducting the haptic research and/or the interface
design are not clearly dis
cussed. The proposal states “this will be done by designing the most
appropriate interfaces for the ERC test beds, and then by extracting the principles from these case
studies.” This approach is considered “reactive” and not proactive or theory/principl
e driven to
identify the best design plans for the human operator or appropriate function allocation assignments
to ensure maximum performance, comfort, and safety. In addition, the key challenges identified
overlook others that are critical given the bro
ader research activities stated in the proposal such as
(1) developing a research methodology for deriving information on what operational cues will be
needed for operation of these complex systems; and (2) research strides to determine function
allocation

and assignment of activities to the human or machine components of the system which
must be done to support the stated goal of creating a “blending of automation and manual control”.


Response
:

Human factors plays an important role and will be a useful co
ntribution to the proposed
compact and efficient fluid power industry. This topic will not only be researched, but it will guide
other rese
arch and it will be applied in C
enter projects and test beds. Selection of human factors
research projects will be b
ased on their contri
bution to the overall C
enter goals


The specific area of human factors where research is most needed to advance compact and efficient
fluid power is the physical interaction between a user and a fluid power machine. Example
machines in
clude an excavator (TB
-
1), a portable, wearable jaws of life (TB
-
5), and an orthosis
(TB
-
6). The physical (or haptic) interaction with these systems reveals fundamental control,
stability, and ease
-
of
-
use issues that are unique to fluid power. Most prior a
nd current research in
physical interaction with machines has been for machines with electric motor drives. The dynamics
of fluid
-
power machines are completely different, and for high force and high power machines such
as the portable jaws of life, safety
and stability are essential. The fluid powered orthosis brings up
new possibilities for an efficient alliance between human and machine to save energy. The dynamics
of throttle
-
less control and novel energy recovery schemes will not be revealed until resea
rch in
thrust areas
1

and
2

are underway, but will bring out new, fundamental research issues in the
design of stable haptic interfaces.


This research is at the frontiers and the ERC team includes some of the best researchers in the
world in this area. T
he ERC research team has considerable expertise in basic and applied
research in haptic interfaces and has conducted preliminary work that demonstrates the unique
nature and challenges of haptic interfaces for fluid
-
power machines research [Love, L.J. and
W.J.
Book, 2004 "Force Reflecting Teleoperation with Adaptive Impedance Control," IEEE Transactions
on Systems, Man, and Cybernetics Part B: Cybernetics, Vol.34, No.1, pp.159
-
165.], [Kontz, M.E.,
J.D. Huggins, W.J. Book and Frankel J.G., “Improved Control
of Open
-
Center Systems for Haptic
Applications,” Proceedings of the ASME International Mechanical Engineering Congress and
Exposition, Nov. 5
-
11, 2005, Orlando, FL, paper IMECE2005
-
81910.], [Li, P.Y. and K.
Krishnaswamy, 2004, “Passive Bilateral Teleoperat
ion of an Electrohydraulic Actuator Using an
Electrohydraulic Passive Valve,” International Journal of Fluid Power, Vol. 13, pp. 43
-
59].


Human factors and human interface design of course encompasses far more than haptic interfaces
and, as pointed out in

the review, include cognitive and psychophysical aspects, classical user

28

interfaces, and multi
-
sensory displays. While not
a main research thrust of this C
enter, the broader
issues of human factors will be addressed where they b
est support the mission of
the C
enter, and
will come into play as the test
-
beds are developed. Best practices in user
-
centered design (e.g.
[Vredenburg, K., Isensee, S., Righi, C., (2001),
User
-
Centered Design: An Integrated Approach,

1
st

Edition,

Prentice Hall]) will be followed th
roughout the development of user
-
operated test
-
beds, in
particular the excavator, hand tools, and orthosis. Human
-
in
-
the
-
loop simulation for operating
fluid power machinery, already in place at Georgia Tech and Illinois, will be used for human
factors expe
rimentation.. The UMN team has conducted research in multi
-
sensory displays
[Hendrix, C, P. Cheng, W. Durfee, Relative influence of sensory cues in a multi
-
model virtual
environment, Proceedings of the ASME Dynamic Systems and Control Division, DSC
-
Vol. 63
, 59
-
64, 1999]. The research team has published on methodologies of interaction design, for example
[
Book, Wayne, "Design of Teleoperators," Chapter in Handbook of Industrial Robotics, Shimon Nof
(ed), John Wiley and Sons, Inc., pp. 138
-
157, 1985.], [Jiang
, X., Bingham, J., Gramopadhye, A. K.,
and Melloy, B., (2000), “A system to Understand Human
-
Machine Function Allocation Issues in
Visual Inspection”. Proceedings of the HFES/IEA Annual Meeting, San Diego, August 2000.],

[Jiang, X., Master, R., Gramopadhye
, A. K., and Melloy, B.J., Grimes, L., (2003), Evaluation of
Best System Performance: Human, Automated, and Hybrid Inspection Systems, International
Journal of Human Factors in Manufacturing, 13(2), 137
-
152.].


NCAT researchers are experts at evaluation of

human performance and have access to students
with a primary research interest in these areas. The NCAT team has broad expertise in human
factors research in function allocation between human and machines, user centered design,
augmented reality, noise, t
elerobotics, and multimodal design. NCAT will be the lead for translating
the fundamental results from the haptic interf
ace research into the broader,

user
-
centered design
approach to human factors as enabling technologies and test beds are developed.



ii.

N
oise Reduction


The acoustic noise generated by hydraulic

compressors is a deterrent for the use of fluid power in
many applications. The noise has been a primary contributor to the recent trend by the
manufacturing sector to shift from fluid powered actu
ation to electric motor drives. The proposed
approaches of active and/or passive control of flow ripples at the pump (the noise source) could
reduce the problem. The development of new numerical techniques to model and predict potential
problems will be
beneficial.


This problem is difficult to solve and many of the ideas proposed for passive noise control have
been experimentally tested during the past 50 years. The extensions envisioned for the existing
numerical simulation codes appear to be very chal
lenging to develop, and will be difficult to
experimentally validate.


For the active approach, even if an array of sensors and actuators could be constructed and placed at
strategic locations in the pump, reliability, complexity, and power consumption cou
ld make the
solution prohibitively expensive.


The results of this research are important for all of the test beds, and can be used by other thrust
areas of the Center.



29

Response
:

Specific noise reductio
n goals are heavily application
dependent. For a typi
cal injection
molding machine (TB
-
2), for example, the goal is for customers to comply with OSHA regulations
for Engineering and Administrative controls,

to

avoid the need for a hearing conservation program,
and

to

minimize occupational hearing loss issues
. This establishes absolute sound power
requirements. Similar goals are relevant for hand tools and excavators (TB
-
1 and TB
-
5), although
the usefulness of acoustical feedback to the operator is an additional consideration.

Prosthese
s
(TB
-
6) pose n
o hearin
g loss problem but will need to operate
quietly from an annoyance and speech
intelligibility point of view. Sound quality studies may be needed to target noise signatures that are
acceptable to the user.

The barriers in all of these cases are very signifi
cant, and innovative noise
reduction methods are needed to address them.


The methodologies proposed combine aspects of other studies on compactness and efficiency, as
well as traditional and novel noise control methods. Control at the source will be achi
eved
passively through optimal

pump

design using
,

for example
, the

CASPAR

code (project 1.B
)

to

reduce both source of pump nois
e, i.e. flow ripple and oscillating force or actively using micro
-
actuators or active modification
of surface topology (projec
t 1.C
). Hand in hand with the
development of micro
-
actuators come

micro
-
sensors, which should prove valuable in the
experimental validations. A better understanding of cavitation inception through project 3c will
help minimize this noise source through m
ore accurate models. Control of the sound path will be
achieved through consolidated model
-
based design optimization to optimally select and distribute
vibration isolation, sound barrier elements, sound absorption technologies, damping treatments,
funct
ionally graded
materials (leveraging project 2.D
), and structural design. The approa
ch is not
merely one of adding
trea
tments

to existing
structures;

rather, it is

a clean
-
sheet approach to the
design of low
-
noise fluid power devices. The benefit of the a
pproach is to achieve max
imum noise
reduction for minimum cost and minimum

system complexity.


Low
-
frequency sound will require the use of active con
trol methods due to the ineffectiveness of
passive n
oise control at low
-
frequencies.
The cost of active sys
tems is rapidly coming down. Active
cancellation headsets, for example, are now

available for less than $20.00.
The actuation power
requirement for the suppression of the ripple in power lines is

very small once the system is
properly

tuned.
Low
-
power ac
tuators may be used, with fluidic amplification to minimize piston
displacement requirements. Further, by integration of sensors and actuators as close to the
physical source of the noise as possible, we fundamentally reduce the need for high
-
channel coun
t
arrays of sensors and actuators, thereby reducing cost and complexity. The most significant
challenge of active control methods is to develop robust control methods, low
-
cost reliable
actuators, and backups for possible system failure. These barriers ca
nnot be overcome without a
concerted effort at applying these methods in various test beds and attack the key issues head on.
This is p
recisely the scope of project 3.B
.


Although passiv
e methods have been known for fifty

years, progress is continuously b
eing made.
Consider
,

for example
,

one stunning fact. Interior noise levels in cars have come down by 20 dB
over the last 25 years. This is because the automotive industry invests heavil
y in this area. In the
mean time
, noise levels in commercial aircraf
t have remained stagnant, due to a lack of incentive
for manufacturers to do something about unregulated interior noise (there is little competitive issue,
customers being trapped). In contrast, the manufacturers of corporate
jets now use assertions of
low

interior noise levels in their marketing. These examples s
how that new materials, design
optimization, detailed dynamic modeling and sound radiation predictions can lead to progressively

30

quieter systems
. In this research the ERC will take the same scienc
e driven approach to reducing
noise in fluid power systems, particularly in pumps, compressors and valves.


iii.

CFD Simulation of Cavitating Flows


The project proposes the use of computational fluid dynamics (CFD) software tools in a more
integrated way in th
e design and analysis of fluid power systems. FLUENT and other tools are now
widely used in fluid power control industry. The PIs did correctly identify the cavitation problem
and it is worthwhile to study it more closely.


Other then using currently comm
ercially available software tools, it is not clear what is
fundamentally or technologically improved in this project


PIs should clearly identify these.
Perhaps, it may be a good idea to have a CFD specialist (who is one of the leading experts in CFD
are
a) in this project. That would take care of most of the concerns regarding this project. This is a
very important topic for the safety and long
-
term reliability of fluid power systems and projects in
this area should be encouraged.


Response
:

C
avitation
-
turbulence
interaction is a major contributor

to overarching project goals of
increased efficiency,

reduced size, and less noise.

Dr.

Frankel

is eminently qualified to perform this
research. He

is a distinguished expert in CFD who has been doing research

on modeling turbulent
multiphase

flows, reacting flows and advanced numerical methods since 1988.


The increased
momentum mixing associated with high
-
in
tensity turbulent flows is

used in the gas turbine industry
to create more compact stable combustors.


This same technique can and should be considered in
hydraulics and fluid power component design.


An increase in mixing and turbulence levels, if not
done properly, can and does often result in increased cavitation and noise (both flow noise and
cavitation
-
noise).


The use of properly contoured flow passages can effectively control (passively or
actively) flow vortical features to minimize ca
vitation and noise.

O
nly with advanced high
-
fidelity
software tools, such as those associated with the use of large e
ddy simulation as

proposed in this
project, can one

hop
e to achieve these

goals.

We are not proposing to use FLUENT or any other commercial CFD software as the primary tool
for this project.


The cavitation models in fluid are reasonable for steady time
-
a
veraged
phenomena, but the quasi
-
steady models are insufficient to capture the rate
-
controlled dynamic
two
-
way coupling with three
-
dimensional unsteady turbulence.


Capturing these effects properly
(which is required for reliable and robust prediction of t
urbulent
-
induced cavi
t
ation) requires high
-
order physics modeling and higher
-
order numerical treatment, both of which will be addressed in
the proposed research using Large Eddy Simulations and coupled thermodynamic and mass
transfer physics.


In particula
r, we

propose to develop the large eddy simulation approach for
application to fluid power components through the utilization of more accurate and geometrically
flexible numerical methods, such as the hp spectral/element method (Deville et al., 2004).


Thi
s
development will include new and novel subgrid
-
scale models for small
-
scale turbulence dynamics
that (as described in the next section) will be able to address the two
-
phase flow aspects of
cavitation.

These models will be tested in research codes to be

developed as part of this project

to capture the
unsteady vortical dynamics associated with fluid power components as well as the coupling with
cavitation. The research will also focus on high
-
fidelity modeling of the cavitation dynamics which
are a funct
ion of vapor pressure, turbulence levels, rate
-
dynamics, etc.


31

The formation of vapor through cavitation

changes the local density and momentum and hence
modifies the original liquid flow, hence a two
-
way interaction occurs.


Cavitation can occur in a
numbe
r of different flow settings but one common form of cavitation associated with fluid power
components is vortex cavitation.


This is related to the unsteady formation of vortical flow regions
whose centers have pressures below the vapor pressure.


It is th
e instantaneous unsteady local
pressure that determines if and for how long cavitation will occur and therefore the extent of the
vortex
-
cavitation interactions.


In a turbulent cavitating flow, it is vital to be able to accurately
predict the unsteady loc
al turbulent pressure fluctuations as input

to any cavitation model.


This
ca
n
be done accurately

with the large eddy simulation technique.


There has been some previous
studies which have examined coupling large eddy simulations with bubbly dynamics and c
avitation
models (e.g. Senocak & Shyy, 2003; Loth et al. 1998; Loth et al. 1997), however these have focused
on simple flow like shear layers and generally neglected surface tension coupling, which is
important for fluid power systems.


Another, key proble
m with previous studies is that the previous
LES models ignored or simplified the coupling effects of sub
-
grid pressure and temperature
fluctuations. We propose to develop new cavitation models that accurately account for these
fluctuations since they can
be critical to the mutliphase dynamics.


For example, we will consider
modification of the Leray
-
alpha model and the Lagrangian Averaged Navier
-
Stokes
-
alpha
equations as particular recent efforts to apply this modeling approach in large eddy simulation
(Mo
hseni et al. 2005; A Dynamic Procedure for the Lagrangian Averaged Navier
-
Stokes
-
alpha
Model fo
r

Turbulent flows, AIAA
-
2005
-
0501).


Extensions of this particular

approach to two
-
phase
flow, as found in cavitation, have not

been tried and offer important

o
pportunities for more
accurate simulation results.


Senocak, I., and Shyy, W., "Interfacial Dynamics
-
Based Modeling of Turbulent Cavitating Flows,
Part
-
2: Time
-
Dependent Computations", 2004, International Journal for Numerical Methods in
Fluids, Vol. 44,
pp
. 997
-
1016.

E. Loth, J. Boris and M. Emery "Very Large Bubble Cavitation in a Temporally
-
Evolving Free
Shear Layer,"
ASME Summer Fluids Engineering Meeting
, Washington, D.C., June 1998.

E. Loth, M. Taebi
-
Rahni* and G. Tryggvason "Deformable Bubbles in a

Free Shear Layer,"
Intl. J.
of Multiphase Flow
Vol. 23,

No. 56, pp. 977
-
1001, Sept.

1997.

Xing
, T.,
Li
, Z. and
Frankel
, S. H., “Numerical Simulation of Vortex Cavitation in a Three
-
Dimensional Submerged Transitional Jet,” Journal of Fluids Engineering, July 2005, Vol.

127, no.
4, pp. 714
-
725
.


Xing, T., and Frankel, S. H., 2002, "Effect of Cavitation on Vortex Dynamics in
a Submerged
Laminar Jet," AIAA Journal, Vol. 40, No.11, pp. 2266

2276.

Palau Salvador, G., Arviza Valvedre, J., Frankel, S. H., “
Three
-
Dimensional C
ontrol Valve with
Complex Geometry: CFD Modeling and Experimental Validation
,”

AIAA
-
2004
-
2422
.


iv.

Leakage Reduction


Leakage through seals poses considerable environmental hazard, and it is one of the objectives of
this proposal to reduce, if not eliminate,
this hazard. The objective will be achieved through
developing three
-
dimensional, high pressure, dynamic shaft
-
seal models that will account for
surface topology and surface material properties of the contact.



32

Professor R. Salant of Georgia Tech is an int
ernationally known author of seal research; he is
particularly well known for his work on micro
-
surface effects on EHD. He will combine fluid
mechanics, contact mechanics, deformation mechanics and thermal processes to build the model.
Professor Salant is
also an outstanding numerical analyst, and will perform the desired task
outstandingly.


v.

Contamination Reduction


The r
esearch on contamination reduction
aims at minimizing the hydraulic fluid contamination by
identifying and eliminating contamination sour
ces, and new filter and engineered material design.
Due to the slow mechanical and chemical degradation, this project may entail large scale and long
duration experimental effort, in order to generate statistically meaningful results. The proposers
have
the equipment needed to make mechanical and chemical characterization of the fluid and
frictional surfaces measurement, however, a detailed methodology for or demonstrated ability in
designing the experiment to collect statistically meaningful samples and
measured data are lacking.
Methodology or demonstrated ability in formulating hypothesis of contamination formation based
on the statistical data is also lacking. The potential problem of introducing new contaminants by the
piezoelectric material driven

active surface from project 1.B is recognized.


Response
:

While we thoroughly agree with the panel’s comment that the mechanical and chemical
degradation is a long process, we do have a solution for generating statistically meaningful results.
In collabor
ation with one of our industrial partners, Prince Manufacturing (a major producer of
hydraulic cylinders), we have established a procedure for collecting a wide range of samples at
various stages of degradation. This is an alternative approach for generati
ng a statistically
meaningful sample to produce statistically meaningful results.


At least 80 % of all fluid power systems fail as a result of contamination (Norvelle, D.F., An
Introduction to Fluid Power, West Publishing Company, St. Paul, MN, 1991. Gsch
wender, L.,
Snyder, C.E. Jr., Sharma, S., Flanagan, S., (Materials Directorate, Wright Patterson Air Force
Base), Advances in US Air Force Hydraulic Fluids, JSL 16
-
1 35 ISSN 0265
-
6582.)
Our hypothesis
is that the main reason

for contaminant formation is th
e mechanical degradation of working metal
surfaces as a result of their chemical modification in the course of

service
. Therefore, we presume
that identifying the chemical reactions responsible for this degradation and their mechanisms is a
critical step i
n finding a w
ay to prevent this degradation
.

O
nce a mechanism is established the
solution of inhibiting this mechanism can be directly approached.


We will use the following methodology
:


1. Generate a testable hypothesis and create an experimental design

to test the hypothesis.


2. Collect
a

statistically meaningful sample
. The sample will include debris, deteriorated metal
surfaces
,

and power fluid collected at various stages of degradation.



3
.
Apply

surface
-
sensitive techniques (diffuse reflectance F
T
-
IR, Raman Spectroscopy, electron
spectroscopies) in combination with Atomic Force Microscopy (AFM)

to identify

the chemical
nature, the mechanical properties, the debris particle size and shape distributions
,

and the surface
morphology and topology of th
e working surfaces an
d fluid.
. Fluid power systems are

free of
contaminants when they start working, so the reactants involved in these reactions (fluid, metal,

33

seals and lubricant additives) are identified. As degradation progresses, new chemical changes
will
occur and the above analysis will in essence identify the products of the reactions under
investigation. The unique part of this experiment is employing single asperity AFM tribological and
mechanical characterization of the debris and metal surfaces,

which is essential in correlating the
chemical changes and the corresponding mechanical changes they induce. For example, a
particular chemical modification of a cylinder surface may lead to an increased friction coefficient,
decreased hardness of the sur
face, which in turn increases the rate of debris formation, the sliding
contact temperature, etc. This is a critical part in testing the proposed hypothesis. No such
experiments have been performed so far. The results obtained in this part of the research
will be
used to propose the chemical reactions responsible for
the mechanical deterioration. Once this is
achieved, a specific mechanism for the reaction needs to be identified.


4
.
The mechanism will be studied in laboratory conditions using model systems

representing the
real ones: metal samples with the same composition and mechanical properties will be used,

along
with

the same (or chemically similar) fluids and lubricant additives. The goal

is to reproduce the
exact chemical and mechanical changes in a
n environment where a detailed characterization as
well as variation of critical parameters, such as temperature, pressure, etc, can be performed and
their influence on the reaction rate can be measured. Once the chemical reaction(s) is(are)
identified, ki
netic measurements will be employed to understand the mechanisms of these reactions.


5.
The ultimate goal is to significantly reduce the rate of formation of contaminants, so in this step
chemical modification of the surfaces and fluid additives will be t
ested to inhibit the reactions
responsible for mechanical deterioration. Examples of such modifications are the use of thin films
(solid or Langmuir
-
Blodget) and additives with different chemical composition
s
.


6. W
hen an appropriate modification is identi
fied, model parts will be produced (in collaboration
with our industrial partners) to be used in any of the appropriate test beds available.


The leader of the project has demonstrated the ability to conduct this research in his earlier work
on extreme pre
ssure lubricant additives in collaboration with an industrial partner (Benz Oil,
Milwaukee, WI
). T
he same methodology was applied in identifying the mechanism of surface
chemical reactions responsible for the significant modification of the friction coeffi
cient of metal
surfaces. I
t has been demonstrated by the leader and co workers that a monolayer thin alkaline
halogenide layer can dramatically reduce the friction coefficient of a metal surface. The ability
under question has been documented in the follow
ing publications in refereed journals:


Kaltchev M
,

Celichowski G
,
Lara J
,
Tysoe WT
, Tribology Letters
9

(3
-
4) 161
-
165 (2000).


Kaltchev M
,
Kotvis PV
,
Blunt TJ
,
L
ara J
,
Tysoe WT

, Tribology Letters
10

(1
-
2), 45
-
50

(2001).



Wu G
,
Gao F
,
Kaltchev M
,
Gutow J
,
Mowlem JK
,
Schramm WC
,
Kotvis PV
,
Tysoe WT
, Wear
252

(7
-
8), 595
-
606 (2002).



Gao F
,
Wu G
,
Stacchiola D
,
Kaltchev M
,
Kotvis PV
,
Tysoe WT
, Tribology Letters
14

(2), 99
-
104
(2003).


T
he lea
der has a long standing collaboration with Dr. W.T Tysoe

of the

Department of Chemistry at
the University of Wisconsin Milwaukee
, a well recognized authority
on the

relationship between

34

tribological properties and chemical

modification.

If needed, resourc
es and expertise from this
group will be attracted to the project.
T
he Director of Reliability and Contamination Control at the
Fluid Power Institute of MSOE, Paul Michael, has more than 20 years of experience in the area
and he will be part of the team wo
rking on this project.

As needed, a statistician will be brought into
the project as a consultant to advise on experimental design and statistical analysis of results.


The

proposed research will be extended to

new

contaminants that may originate from usin
g new
piezo
-
controlled surfaces (project 1.B) and also to contaminants resulting from seal
-
metal
-
surface
interactions. An optimistic discussion related to this issue occurred between the leader of this
project and Dr. Salant, emphasizing the benefit of app
lying the described approach to these
interactions.






35

Test Beds


i.

Excavator


The excavator is a widely used and functionally important piece of construction machinery. This
device currently uses large
-
scale hydraulic fluid power and thus provides an opp
ortunity to explore
and enhance discovery of various research theories and principles proposed in the area of efficiency
within the proposed ERC. Caterpillar, a large manufacturer of such systems, is a member of the
Center, so this relationship provides t
he opportunity for researchers to acquire and experiment with
such a device. In 2000, Lumkes and Franczak demonstrated that using a switching valve was
beneficial in recovering and storing energy, giving a good example of the specific gains to be made
usin
g this test bed. Also, in 2002, Wendel tested and proved that up to 46% energy savings can be
realized by using regenerative concepts and valve elimination. These research findings are
encouraging and supportive of the inclusion of this test bed into the
proposed research efforts.


ii.

Injection Molding Machine


Injection molding machine test bed represents a industrial manufacturing machine that have
traditionally used a fluid power source for precisely controlling the velocity and pressure profile of
the i
njection process to render desired material and geometrical properties, but at a low efficiency of
10
-
20%. The injection molding machines in UM and UIUC are readily available for integrating
this test bed that incorporates new efficiency features, such a
s throttle
-
less, on
-
off valves (Project
1.A) and pump displacement PWM control (Project 1.E) . The UM and UIUC researchers have
extensive experience with the injection molding machines and process. This test bed allows
experimental investigation of the th
rottle
-
less, on
-
off valve control for substantially improving
efficiency and demonstrating this technology in the early stage of the Center. Risk factors in this
test bed include the fact that smooth and precise control may not be possible to satisfy the
injection
process requirement by the on
-
off valve control. Fluid powered injection molding machines are
also being replaced by electric motor driven machines, indicating that fluid power’s power margin
or power density level is not comfortably higher than

the electric motors for this particular
application. However, the benefit of using this test bed for demonstrating efficiency improvement
in the early stage as a showcase overrides the risk factors.


Response
:

The injection molding machine

is appropriat
e for demonstrating several of the efficiency
benefits. It will also serve as an integrating test

bed where several of the efficiency hardware
concepts need to be integrated with appropriate sensing and control approaches.
Noise reduction
and leakage prev
ention are also important in the application.

One of the key aspects of an injection
molding process is the rapid fill (velocity control) phase that transitions quickly to a packing
(pressure control) phase. Currently fluid power machines handle the pres
sure control phase by
means of a relief device and a load
-
sensing pump
that
introduce inefficiencies in the system by
wasting some energy across a throttling device (relief valve). A key to this testbed is to see whether
the same quality of fill
-
to
-
pack t
ransition, and flashing avoidance, can be maintained with the use of
throttle
-
less hardware. Another key is to determine whether or not packing control can be
maintained with high efficiency throttle
-
less or pump displacement systems, given the fundamenta
l
limitations of hydraulic pressure/force control (Alleyne & Liu, 1999).

New control laws will be
developed as needed to control injection molding.




36

iii.

Small Urban Vehicle (sUV)


Opposite of SUV (sport utility vehicle), sUV provides an excellent platform to
test many of the
ideas outlined in the proposal. This test bed can serve as a hardware test bed for the free
-
piston
compressor, energy regeneration during braking or downhill travel, compact accumulators, and
on/off valve based pumps and motors, haptic (f
orce feedback) capability on the steering wheel and
control paddles. It is valuable that an existing center at University of MN on Human Factors will be
involved in this project. This could also serve as a great motivator for students as an educational
platform.


iv.

Compact Rescue Crawler


The Compact Rescue Crawler is a potentially important test bed for integrating several of the
research projects proposed under this ERC. The conceptual design is for a hexapedal robot
operating un
-
tethered and with human
supervision via a wireless link. The exact scale is not
specified but it seems likely that it will use actuators comparable to those anticipated for the
powered orthosis. A number of hexapedal robots that have used hydraulic or pneumatic power over
the yea
rs. In all cases they have either been large, so that a gasoline engine and pump had to be used
to provide hydraulic power, or small or tethered, with off
-
board supply of fluid under pressure.

In comparison to electromagnetic actuation, fluid power confer
s important advantages for compact
limb design and for load matching for efficient locomotion. However, where it has been used, the
results have been fraught with all the problems identified in the introductory section of the proposal.


The availability of

compact, low
-
noise power generation and the ability to utilize regeneration are
particularly exciting for this application, both to increase mission life and to reduce wasted heat.
The human interface is potentially an interesting control problem, but it
is not clear what issue the
fluid power aspects of this test bed will elicit that are distinctly different from the human/machine
interface issues addressed for other hexapedal robots in the literature. But as an example, power
management may be an activit
y that humans will want supervisory control over, to prolong
missions and reduce heating.


The team responsible for the development of the crawler is based mainly at Georgia Tech. and
Vanderbilt and has the expertise needed to incorporate the fluid power i
nnovations into this
platform. The benefits to industry from this platform will mainly be indirect, as the market for
rescue crawlers is not large. However, the advances in practical compact power generation and
regulation are important for the fluid power

industry and for end applications in the power tool and
automotive industries.


Response
:
The unique challenge in human/machine interactions in regard to this test
-
bed are
concerned with the requirement for energetic efficiency, the need to coordinate the

large degrees of
freedom motion in the system, and the unique dynamics that the new compact and efficient fluid
power will present. There must be a blending between automation and direct human control that
considers energy and power management, including
the determination of different gait modes
according to energetic and performance requirements.


While we cannot estimate the future market size of rescue crawlers, the range of

future

applications
that this test
-
bed
supports

may be quite l
arge,

including
a host of autonomous robots capable of
sustained and untethered operation.


37


v.

Power
-
Assisted Hand Tools


The proposed test bed is supposed to demonstrate the application and integration of (a) self
-
powered chemo
-
fluidic concept, (b) free
-
piston engine compr
essor or high
-
energy accumulators,
and (c) haptic interfaces. The featured hand tool is the existing, tethered hydraulic
-
powered “Jaws
-
of
-
Life” rescue tool. Although it would certainly be beneficial to create an untethered tool of such a
kind (for rescue a
nd many other applications), it is not clear if the chemo
-
fluidic concept scales up
to provide the power needed to tear metals in rescue operations. It order to generate say 3000 psi
(typical of hydraulic systems), the chemo
-
fluidic system may require a la
rge piston which can
render the new un
-
tethered tool too heavy to be portable. The projects (2A, 2B. 2C and 3A)
identified in this test bed seem reasonable from a qualitative point of view. As these projects (2A
and 2B or 2C) mature, it is important to re
-
evaluate the size and scope of hand tools in general, for
which the proposed concepts can make a truly positive impact and the Jaws
-
of
-
Life type hand tools
in particular.


The use of a free
-
piston IC engine integrated with a pneumatic compressor or a pump
/motor to
power hydraulic systems might render a “hand tool” too bulky and too heavy. The proposal did not
present a quantitative assessment of potential application of projects 2B or 2Cfor hand tool
application. A quick reality check is needed before emba
rking on this seemingly promising
application.


Response
:

One reason that TB
-
5 Fluid Power Assisted Hand Tool was chosen as a test
-
bed is to
demonstrate and drive the requirements for the new portable fluid power

supplies. W
e believe that
each of the prop
osed power supplies (chemo
-
fluidic (2A), free
-
pist
on engine (2B), or accumulator
(2C)
) is a feasible option. As research in each of the proposed method develops, quantitative
assessment will be conducted and the most appropriate option chosen.


C
hemo
-
fluid
ic
actuation (2A) is well suited to the Jaws
-
of
-
Life rescue tool

if a configuration is used
that gene
rates hydraulic power from the
monopropellant.


This

is similar
to an approach already
used as
auxiliary hydraulic power supplies in the Space Shuttle and
in F
-
16 aircraft. The use of
propellant
-
based
,

high
-
pressure hyd
raulic power supplies in these
large
-
scale systems serves as an
exi
stence proof that the proposed
approach scales
-
up to the pressures
required of these tools
(which use

five to te
n thousand ps
i.

hydra
ulic cylinders, depending
on the make and model of the
tool).


Unlike th
e systems in the Space Shuttle
and F
-
16, which use impulse turbines and throt
tle
-
based hydraulic servo
-
valve
control, the proposed chemo
-
fluidic approach will incorporate a


ho
t
gas v
ane
motor (project 2A) and will utilized throttle
-
less control.


In reference to a free
-
piston IC engine (2B) being too bulky for “hand tools”, one example of a
currently existing self
-
powered hand tool that utilizes something akin to the proposed f
ree
-
piston IC
engine is a cordless nail gun (e.g. Paslode Cordless Framing Nailer part #900420, powered by a
butane fuel pack). As with this example, the development of such hand tools will require a careful
match of the energy liberating process to the sp
ecific load being considered, as opposed to
designing a general plug
-
and
-
play energetic source “component”.


vi.

Orthoses



38

The orthoses test bed is an important application of fluid power that has significant potential to
assist physically disabled individuals
. There is a growing community of elderly people who would
dramatically benefit from such a device. In recognition of this need, several rehabilitation research
groups worldwide have already started to develop pneumatic and hydraulically actuated orthose
s.

Due to power supply inefficiencies, none of the existing machines are non
-
tethered, hence a
compact power source that could provide a compressed gas at high pressure for a sustained time
would have significant impact.


The proposed chemo
-
fluidic power s
ource will be difficult to make compatible with humans. The
elevated temperature, relatively high complexity, and weight all pose significant challenges in the
design of such a device. While the energy density of chemo
-
fluidics may be better than that of

batteries, it will probably not be high enough for sustained operation with moderately impaired
subjects. There was no mention of energy recovery for this fluid powered device.


This project is less coupled to the goals of the Center than some the others
. The power source is at
a smaller scale than what is needed by the other projects, with the exception of the crawler.



An energy storage accumulator would not be used for regeneration.


Response
:

T
he orthosis testbed is an important application of flui
d power that has significant
potential to aid persons with disabilities
. I
mplementation concerns
of using chemofluidic actuation
in this application
can be addressed v
ia good design. I
t is impo
rtant to note that
chemofluidic
actuation is only one of sever
al potential power supply and actuation approaches proposed for the
orthosis test

bed. For example, feasibility studies have been conducted that indicate, with
moderate levels

of assist and with sufficient
energy recovery, gait assistive devices can be
d
eveloped based on a belt
-
mounted battery pack and electrically driven pump that powers a set of
fluid
-
powered actuators. Regarding the notion of energy recovery, the investigators have
conducted extensive studies on the use of energy recovery systems in l
ong
-
leg orthoses (e.g., see
Durfee and Rivard, Preliminary design and simulation of a pneumatic, stored
-
energy, hybrid
orthosis for gait restoration, IMECE International Congress, November 2004). Such work will be
leveraged in the development of the propo
sed orthosis test

bed.


The orthosis is directly coupled to the goals of the ERC
as it presents the most stringent design
requirements for compactness, efficiency, noise, leakage, safety and ease of use. The knowledge
base and enabling technologies from al
l three thrust areas are connected to the orthosis.



4.

Education and Educational Outreach


Review Criteria:



Education plan integrates the ERC's research activities and results into curricula at all
levels (pre
-
college through life long learning);



Education/
research programs will achieve a team
-
based, cross
-
disciplinary culture for
undergraduate and graduate students;



Effective plans for implementation, assessment and dissemination of curricular
materials;



39



Outreach will expose a broad spectrum of faculty, te
achers and students to the ERC's
research culture, impact pre
-
college curricula and motivate students to study
engineering.


The education and outreach efforts of the proposed effort include plans for new curricula at the
undergraduate and graduate level,
as well as ideas for REU activities. Also, the PIs propose to work
with Project Lead the Way to influence the development of materials for high school students t
o
increase their awareness of e
ngineering as a career field. In addition, the ERC team plans
to work
with the Minneapolis Museum of Science to develop a hands
-
on interactive module to explain the
concepts of fluid power to children of all ages. The proposal lacked a few specifics of the exact
plans for educational programs and some of the plans f
or curriculum development were not fully
disclosed in the proposal. During the site visit, additional questions were asked and information
was provided to assure the team of the research
-
driven approach that will be used to develop the
education and outre
ach activities to ensure that the goals of the education and outreach components
are attained. The site visit team was assured that the outreach efforts of the ERC would be guided
using research findings and best practices learned from informal education
and prior outreach
efforts targeted at increasing awareness and attracting students to pursue careers in STEM fields.
Given information presented during the site visit, it is envisioned that the research findings from the
work of the proposed ERC will be s
uccessfully integrated into existing courses within the
curriculum that will expose students to the topic and broaden their understanding of the
fundamental theories, principles, and practices that need to ensure their preparation for performing
work in th
e area of fluid power. The additional information shared during the site visit provided
examples of activities that will be undertaken at all of the institutions involved to ensure that efforts
associated with broadening the participation of females and

members of underrepresented groups
are a top priority of the Center.


The proposal does not present a plan for implementing ideas or a plan for dissemination of
education activities to other institutions or the scientific societies or communities.


Th
e proposal plans to introduce students to research through its Research Experiences for
Undergraduates program. There will be internships in industry and museum exhibits with hands
-
on
activities that are hoped to excite and interest students in engineeri
ng. During the site visit, it was
stated that the specific activities of the outreach efforts will be guided using research findings and
best practices learned from informal education and prior outreach efforts targeted at increasing
awareness and attract
ing students to pursue careers in STEM fields.


Response
:



Implementation pla
n.

SMM will start the interactive exhibit and youth training projects in Y1.
Prototype exhibits will be ready in Y2 and the final exhibit ready in Y3. Emphasis will then shift to

youth training and replication of the exhibit. In Y4, Y6, and Y8, the exhibit will be updated to
incorporate research results from the ERC. PLTW will start development on the new middle and
high school curriculum in Y1. The curriculum will be piloted in Y
2 and ready for full dissemination
throughout the PLTW network schools in Y3.
In s
ucceeding years
we
will
evaluate
curriculum
effectiveness, and update the curriculum based on ERC research results. Take
-
home lab project will
begin Y1. Kits will be develope
d, piloted and evaluated in Y1
-
Y3. In Y3 or Y4, kit plans will be

40

available for nation
-
wide dissemination. Int
ernship program will start Y1. A d
etailed plan
s

for these
and remaining education activities will be developed during the ERC strategic planning p
rocess.


Dissemination plan
.

Presentation at national and international conferences, including fluid power
technical conferences and the ASEE education conference. Publication in fluid power and
education academic journals. Dissemination to industry throu
gh ERC industry advisors and via
NFPA publicity and marketing activities, as well as at the NFPA annual conference. Dissemination
to the museum community via The Association of Science
-
Technology Centers publications and
annual conference
s
. Dissemination o
f recruiting and mentoring activities through appropriate
publications and conferences.


5.

Industrial/Practitioner Collaboration and Technology Transfer


Review Criteria:





Proposal provides a convincing rationale for the selection of industrial/user partne
rs
and engages these partners in planning, research, education, and technology transfer;



Significant level of commitments from firms to be fee
-
paying members of the ERC, if an
award is made, given the industry;



Proposed terms of the industrial membership a
greement will structure a center
-
wide
program of industrial collaboration to support overall ERC goals, as opposed to a
collection of individual sponsored projects;





Proposed terms of the intellectual property policy will facilitate technology transfer
.


The strongest element of the proposal is the unprecedented level of industrial support extended to it
by the North American Fluid power industry. Given the past record of involvement of this industrial
sector in university
-
based research, this level of sup
port is remarkable and unlikely to be repeated.


Forty
-
eight industrial participants have committed themselves to support the research and the
educational objectives of the center. The goals of the Center are indeed aligned and reflect the most
significan
t challenges of the fluid power industry. The industrial partners involved with the Center
span the entire life cycle of the fluid power industry and include component manufacturers,
suppliers, system integrators and users. The combined involvement of Par
ker Hannifin, Eaton, and
Moog should be noted as these corporations have the ability to transform the fluid power industry,
internationally.


The industrial support is not specific to projects, as is customary for ERC, and is for the overall
activity of t
he Center through a fee
-
paying arrangement. Project specific contributions are also
made in the form of in
-
kind support. Their commitment to training is very evident by their support
of the internship program proposed by the Center. The intellectual Proper
ty agreement between the
participants is well defined and forms part of the membership agreement signed by industry
collaborators.


6.

Management, Infrastructure, and Diversity



Review Criteria



Institutional configuration is appropriate to the research and e
ducation goals of the ERC;
at least one core or outreach partner is a predominantly minority or female serving

41

institution; there is a partnership with a Louis Stokes Alliance for Minority Participation
and other NSF diversity awardees; collaboration is in
tegrated across the participating
universities;



ERC has expertise in all disciplines required to attain its goals and a capable leadership
team;



Diversity strategy will yield a center whose leadership, faculty, and students are more
diverse in gender, race
, and ethnicity than national engineering
-
wide averages and ERC
will likely have a significant impact on the diversity of the engineering workforce;



Organizational structure and management plan effectively organize and integrate the
resources of the ERC to

achieve its goals and include strong advisory and project
selection/evaluation systems; the resources of the lead and core partner institutions are
be effectively integrated;



Experimental, computational, and other required equipment, facilities, and labor
atory
space are in place or proposed to support the research of the Center;




The lead and core partner institutions will join in partnership to facilitate the inter
-
institutional configuration, reward interdisciplinary research and the integration of
resea
rch and educational, and deliver on the ERC’s diversity goals;



Headquarters space proposed for the Center will effectively encourage and facilitate
interdisciplinary collaboration and house the management functions of the ERC.



The proposed ERC involves p
artnerships with LSAMP programs at NC A&T and Georgia Tech as
well as AGEP programs at Georgia Tech. These programs have been very successful in attracting,
retaining, and graduating students from underrepresented groups in engineering. During the site
vis
it, the ERC leadership team produced plans for ensuring the incorporation of females and
members of underrepresented groups into the mainstream activities of the center as well as REU
programs.


The Proposed leadership team appears to possess the requir
ed level of knowledge, research
expertise and years of experience needed to successfully guide the efforts of the proposed ERC.
The PIs represented and the programs included are well known and well respected in the areas of
Mechanical Engineering.


Of the

three thrust leaders of the proposed Center, one is a women and one is an African
-
American
male. Many of the institutions involved in the proposal have successful Minority Engineering
Programs that can assist in ensure the participation of persons from di
verse backgrounds.
Involvement with these programs is not mentioned in the proposed activities.


The Organizational structure and the plan for selecting, sun
-
setting, and adding additional
researchers that was developed and presented by the leadership t
eam during the site visit should
serve as a guide to facilitate successful operation of the Center.




The Institutions involved have state of the art facilities for executing the strategic vision for the
proposed ERC. The proposed Center appears to have

good administrative support. It is
questionable if the proposed Center will have the professional staff support needed to ensure
successful logistical operation of the proposed Center.



42

Assurances were given by top academic administrators from all part
ner institutions that
coordination mechanisms and evaluation criteria were in place to assure effective inter
-
institutional
collaboration and the reward of participating faculty. They committed to 10
-
12 new faculty hires,
with emphasis on improving divers
ity.


The lead institution appears to have the space needs to accommodate the headquarters functions of
the Center.


Response
:

Professional staff support to ensure successful logistical operation of the Center has two
components. First, the to
-
be
-
named ERC

Administrative Director will work closely with the ERC
Director and the Executive Committee on Center operations. Second, NFPA will provide logistics
support to the ERC through its professional staff of eleven. NFPA support was key in proposal
preparation
, particularly through sponsoring webcast meetings and coordinating industry
implementation. Each site has professional staff to assist in ERC operation, and additional staff will
be added as needed.