Indoor & Outdoor Location of Firefighters & Safety Personnel

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Dec 4, 2013 (3 years and 8 months ago)

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I

I
ndoor

&

O
utdoor

L
ocation

of

F
irefighters

&

Safety Personnel


An Integrated Approach



Final Report
Submitted to

Maryland Fire and Rescue Institute

Submitted by




Dr. Neil Goldsman

(301)405
-
3648

neil@eng.umd.edu



D
r. Gilmer Blankenship

(240)790
-
0620

gilmer@technosci.com





April 14, 2006





Contents

Section I.

Abstract

................................
................................
................................
.............................

1

Section II.

Final Report

................................
................................
................................
......................

2

a.

Introduction

................................
................................
................................
........................

2

b.

Indoor / Outdoor Tracking Performance Trials

................................
................................

4

c.

Detailed Technical Description and Approach

................................
................................

6

c.1.

Integrated Positioning

................................
................................
................................
..

6

c.2.

Elements of the Existing Sentinel System

................................
................................
..

8

c.3.

3D Graphical User Interface

................................
................................
......................

11

d.

Miniaturization of Prototype

................................
................................
............................

14

d.1.

INU Improvements

................................
................................
................................
.....

17

e.

Node Controller

................................
................................
................................
...............

20

f.

Future Work

................................
................................
................................
..............................

21



Figures


Figure 1. Fire Sentinel Beacon has 2 pieces, the INU is worn on the firefighters belt. The
INU is connected to the radio via blue tooth. The radio can be connected in any
convenient locati
on so as not to interfere with movement or other gear.

..............................

2

Figure 2 (Left) Trajectory produced by the Sentinel INU of a user walking on the third floor
of the AV Williams Bldg. (Right) The actual path the user walked inside the

building.
The journey lasted about 5 minutes.

................................
................................
........................

4

Figure 3 Shows a path traversed outdoors, around a relatively large building by a user of
the prototype Sentinel Beacon. The path is 2/5 of a mile. No GPS is used.

.........................

6

Figure 4 Inertial Navigation Unit

................................
................................
................................
......

9

Figure 5 Transceiver module and RSSI display

................................
................................
.............

9

Figure 6 Motherboard of prototype sensor interface.

................................
................................
...

10

Figure 7

GPS System designed by TRX

................................
................................
......................

10

Figure 13. System Block Diagram

................................
................................
...............................

11

Figure 8 A part of the path shown previously: (Left) Path plotted (in real
-
time) on a floor
plan using prototype map
-
matching Vi
rtual Reality software. (Right) 3 dimensional
VR view of the unit moving on the floor plan.

................................
................................
........

13

Figure 9 Building internal structure constructed by JAVA3D map
-
building software for the
path shown earlier using data provided b
y the INU.

................................
.............................

14

Figure 10. First Generation INU Block Diagram

................................
................................
..........

17

Figure 11. Second Generation INU Block Diagram

................................
................................
....

17

Figure 12. Second Generation INU Boards a) INU mai
n board is worn vertically with back
against firefighter’s belt. b) INU secondary board inserts into the main board at silk
screened rectangle and allows for tracking of firefighters in non
-
vertical orientations
such as crawling.

................................
................................
................................
....................

19

Figure 14 Liteye HUD mounted on a helmet. The viewer is “transparent” enabling the user
to see objects ahead.

................................
................................
................................
..............

24




FINAL REPORT

12/4/2013


PAGE
1

Section I.

Abstract

In work funded by the Department of Homeland Security

(DHS)
,

the Maryland Industrial
Partn
ershi
ps P
rogram

(MIPS)
and the Mar
yland Fire and Rescue Institute

(MFRI)
, an
innovative technology
prototype
for tracking individuals moving inside buildings and
structures

(and outside as well)

has been developed
.
Specifically, t
he Sentinel System
is

desi
gned to locate and track firefighters
and other first responders
indoors and outdoors
using
inertial and other measurements
, including GPS signals, if available
.
The system

includes a
Sentinel Beacon
and a “Command Station” (a ruggedized PC) that receives
the data
transmitted from the
b
eacons and processes it to produce location and track information for
the incident commander. The
Sentinel Beacon
system is designed to work as a “mesh
network” so that a beacon that is out of range of the command station can

have its data relayed
by other beacons.

We have been able to leverage the ongoing work for DHS and MIPS to allow us to
accomplish the results presented here. The funding from the University of
Maryland Fire

and
Rescue Institute

has been used to support
the miniaturization of the prototype hardware.
FINAL REPORT

12/4/2013


PAGE
2


Section II.



Final Report

O
ur
previous

work established a
strong
foundation
for
the project
by developing and implementing
a prototype

i
ntegrated
p
ositioning technology

for indoo
r and
outdoor tracking. The development of the prototype
system has been supported by

the US Department of
Homeland Security (DHS)/Technology Support
Working Group (TSWG) and
the Maryland Industrial
Partnerships Program (MIPS)
. We have been able to
levera
ge the ongoing work for DHS and MIPS to allow
us to accomplish the results presented here. The
funding from the University of
Maryland Fire and
Rescue Institute (MFRI)

has been used to support the
miniaturization of the prototype hardware.


a.

Introduction

The ability to accurately track first responders at
incident sites both inside and outside structures is a top priority for safety and command and
control. Our

Sentinel

System
is designed to enable the Incident Commander to locate and
track responders in
side a building, or in the vicinity of an incident. The
Sentinel

System
consists of the following elements:



A compact, body worn unit (a
Personal Locator Beacon


PLB) that computes
the
responder’s

location in absolute coordinates and communicates it local
ly to

Figure
1
.
The second generation
Fire Sentinel
Beacon has 2 pieces, the INU is worn on the
firefighters belt. The INU is connected to the
radio via blue tooth. Th
e radio can be connected
in any convenient location so as not to interfere
with movement or other gear.

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12/4/2013


PAGE
3

the
Incident

Commander. The capability to relay data from out of range nodes
is also provided by

PLB units;



A Base Station

that enables the
Incident

Commander to see the locations of all
the
responders

in the squads (at the scene, both inside and ou
tside), together
with other information such as
responder health, equipment condition,
environmental data,
building plan, assets, etc.; and



A Communications Network that links all
responders

and the Commander(s).

The initial product will compute location

and measure basic health status of the responder
(body temperature, pulse rate, net movement, impact alarm, etc.) and transmit location, health
status
,

and alarms to the base station. It will transmit an alarm when the responder’s status
leaves
a

nominal
range, or when the responder activates the alarm manually.

The base station will show the
Incident

Commander
where the responders are as mapped on a
3
-
D “floor plan” displayed using a graphical user interface. The personnel locations and
tracks will be sh
own on a building plan or, if a building plan is not available, a map of the
building will be developed implicitly from the historical path data.

An important feature of our system is that, all of the mobile units form a mesh network so if a
responder go
es out of range of the base station transceiver, as long another mobile unit is in
range of the responder and base station, the information can be forwarded to the base station,
effectively extending the range using multiple hops to get out of the building
. Finally, the
environmental data collected by the sensors in the unit can be used to create a “map” of the
environmental
conditions inside the structure. No other system has this collection of broad and
rich capabilities.

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12/4/2013


PAGE
4

With our system, i
f a
responder

goes down

the Commander

will know

where they are and how they got there
.


While the responders will go after
a

comrade with that knowledge, it may still difficult to find
their way to the downed comrade if, for example, the room is filled with smoke, so o
ur mobile
units will have LED indicators to indicate direction and distance to a downed responder.
Future designs will include a heads up display to aid in locating responders. The display
will

include a map of the individual’s path through the structure

and other mission specific critical
data
.

b.

Indoor
/

Outdoor

Tracking
Performance
Trials

In the figures that follow we
summarize

evaluations

of the performance of the
current

Sentinel
System in tracking individuals inside and outside
a building
. The tests
were conduct
ed

at the
AV Williams Building
1

at the University of Maryland in College Park

in
Feb
ruary

2006
. This
is a four story building with a complex internal structure. It houses the Electrical Engineering



1

http://www.umd.edu/CampusMaps/bld_detail.cfm?bld_code=AVW
. See also
http://www.ee.umd.edu/Map/Avw/

for floor
plans.


Figure
2

(Left) T
rajectory produced by the
Sentinel
INU of a user walking on the third floor of the

AV Williams Bldg
.

(Right) The

actual p
ath the user walked inside the building.
The journey lasted about 5 minutes.

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12/4/2013


PAGE
5

and Computer Science Departments, and contains a large amo
unt of electrical equipment


a
potential source of interference with the Sentinel System.

The first trial (
Figure
2
) shows the track of an individual walking in the hallways of the third
floor of the building. The track was take
n in a continuous experiment that lasted about 5
minutes. Note the straight lines of the path corresponding to the long corridors in the building,
and the sharp 90
o

changes in the track as the individual turn
s

each corner. Note also the
accuracy of the uni
t as the individual moves back along the same corridors. Since the return
paths overlap the outward bound paths, we conclude that the location error is less t
han the
width of the corridor (
6 feet). As the data trajectory indicates, the INU sends more data
when it
perceives a turn in the path.

A video demonstrating
the indoor tracking
capabilities of
the Sentinel System

is

available for
review



specifically a recording of
the
experiment

shown in
Figure
2
.
This video can be viewed
by downloading
a Windows Media file
from the TR
X
Systems website:

http://www.trxsystems.com/downloads

Login as “
MFRI
” with password “trackme”
.

Download the file named “TRX
Tracking Demo” to your computer

and view
it
using
the
Windows Media Player.
2

The trial displayed in
Figure
3

is a path of about 2/5 mile traversed outside the building. The
individual stayed as close to the walls of the building as possible during the journey (
to
provide a reference for accuracy). The trajectory is overlaid on a satellite image of the building
from the Google Earth web site.
Although the experiment was outside, we did not use GPS



A DVD with a larger format vers
2

ion of the video is available.

FINAL REPORT

12/4/2013


PAGE
6

data


only the Sentinel INU. If typical GPS accuracy is 2
-
10 mete
rs, then the
location

results
from the Sentinel unit are
better than GPS.


Figure
3

Shows a path traversed outdoors, arou
nd a relatively large building


by a user of the prototype
Sentinel Beacon
. The path is
2/5

of a mile. No GP
S is used
.

c.

Detailed Technical Description and Approach

We
call

our approach
Integrated Positioning
. Integrated positioning combines several
technologies to obtain accurate position estimates. The integration of the different
technologies is seamless to th
e user and provides more robust, accurate position estimates than
a single technique used alone. The final Personal Locator Beacon (PLB) unit worn by a first
responder will contain all of the integrated positioning subsystems and will be approximately
the
size of a cell phone. The information obtained by
the

mobile PLB, is then transmitted to
the base station. In addition to communicati
ng

with the base station, the mobile PLB also
supports

communication of positioning
and condition data

to other responders
at the incident.

c.1.

Integrated Positioning

The positioning technologies used in
Integrated Positioning

are summarized below:

FINAL REPORT

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PAGE
7



Inertial Navigation Unit (INU):

Contains a
MEMS
-
accelerometer,
MEMS
-
compass
and
MEMS
-
gyroscope to track an individual’s motion. We

have already developed a
first generation of the hardware, most of the signal processing software, and a
functioning prototype. The accelerometers
are

also
used to
determine if a responder is
not moving or undergoes a rapid acceleration, e.g., falls throu
gh a floor or gets
knocked over.

The
Sentinel
INU is targeted toward monitoring the position of personnel and is
capable of accurate location
s over a longer period of time
compared to
conventional

I
N
U’s. The data processing methods are targeted specific
ally toward recognizing
distinctive characteristics in human gait and
to
take advantage the gait properties and
their relation to movement. By monitoring and analyzing specific characteristics,

the
INU’s processor uses
specific

filtering techniques to com
pare the recorded motions
with a library of predefined gait motions
.



Global Positioning (GPS):

A small unit based on the latest GPS receiver chips that
can track at
very low signal to noise ratios (
SNR
)
. We have designed the hardware and
software that enab
les the realization of this chip in a GPS receiver. A prototype of this
subsystem
about

the size of a postage stamp has already been developed

and
integrated into the Sentinel Beacon.



Received Signal Strength Indication (RSSI):

Each base station and PLB w
ill have
the capability to measure the signal strength of received radio signals. The weaker the
signal, the further the responder is from the signal source. This method is also used to
determine distance between responders in the network. RSSI becomes ve
ry accurate
when the transmit/receive pair are in close proximity to each other, for example, in a
FINAL REPORT

12/4/2013


PAGE
8

room or large open area. RSSI can be used as a backup to locate downed responders
in a situation where vision is impaired such as in a smoke filled room. A

prototype for
hardware and software has been developed.



Mesh Network:

The mobile nodes in our sentinel system form a mesh network. By
forming a mesh network data is allowed
to be routed (“hopped”) though other nodes if
the nodes cannot form a direct link

with the base station. The ability to hop extends
the range of the system.
Each member of the team
is thus

networked to each other,
and
each node in the
network
can know

the location and other pertinen
t data of the
other nodes
.

A

working system

has be
en
tested in prototype form
.



Active Radar
:

This location method u
ses
extremely accurate
GHz clocks and
electromagnetic ultra
-
wide
-
band pulses for positioning. This method is very similar to
police and aircraft radar. However, it uses ultra
-
wide band techn
ology and transceiver
pairs as opposed to the passive reflection of radio waves employed by existing
systems. Theory, algorithms, and
proof of concept

hardware have been developed.

c.2.

Elements of
the
Existing Sentinel System

The p
ositioning technology
uses

multiple

sensors,

subsystems
,

and
algorithms
to

determin
e

the location of the tracked personnel. The data from each subsystem is fused
onboard the
Sentinel Beacon and in the Sentinel Command Station
. Using data fusion and
complex

algorithms,
the
integrated

positioning

software

is able to locate personnel both indoors and out

with excellent accuracy
. The subsystems are integrated into a small motherboard that
coordinates their operation.


The

subsystems used in
the integrated p
ositioning
system
are summariz
ed below:

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12/4/2013


PAGE
9

Inertial Navigation Unit (INU):

The INU

subsystem contains a
MEMS
accelerometer,
compass and gyroscope. The information from these
micro
-
sensors is combined using
novel

signal
proces
sing algorithms, programmed into
microprocessors, to track the path taken by
an individual
on foot. We use this technique inside
buildings
and structures
where GPS
is not effective
.

Received Signal Strength Indication (RSSI):

This subsystem uses the radio
signal strength
of the
beacon transceiver

to measure the distance from
an individual

to

the
Command Station
.
This method is useful for
homing

in on
an individual

during a search and rescue operation.
Figure
5

shows a prototype of
the transceiver equipped with RSSI capabilitie
s and
the base
-
station interface with the RSSI data. The circle indicates the distance of
an individual from the
Base Unit.


Figure
5

Transceiver module and RSSI display

Motherboard:

I
n
Figure
6

we show the motherboard for the current Sentinel Beacon. This
unit is currently being miniaturized

under funding from DHS
. The
motherboard was designed
to operate with a wide assortment

of plug
-
and
-
play sensors. (
TRX Sy
stems

developed the
interface hardware and software that allowed these sensors to be plug
-
and
-
play.) This is

Figure
4

Inertial Navigation Unit

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PAGE
10

reflected

by the eight rows of connector pins, where various sensors plug into
the

motherboard, depending on the application desired by the user.


Figure
6

Motherboard of prototype

sensor interface
.


We will

continue to provide an option for adding a
plug
-
and
-
play modular sensors, as desired by the
user.

The
PIC
m
otherboard microprocessor will be
programmed to interpret the data obtained from these
plug and play sensors, and incorporate the
information into the node report that will be sent to
the Base Station.

Global Positioning (GPS) Unit:

This is a

subunit
that employs
the latest

single chip
GPS
receivers,

which is shown in

Figure
7
. The GPS unit can
usually provide tracking information
outdoors.

GPS is not effective for indoor tracking.


Figure
7

G
PS System designed by
T
RX

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PAGE
11

c.3.

3D Graphical User Interface

The Sentinel Base Station is a

Panasonic Toughbook, a rugged
ized

laptop that runs standard Windows
operating system
s
.
The
user interface

can

plot the trajectory of the personnel

and archive the data
.
Future plans
include
enhancement

t
he base station
with algorithms which help to eliminate errors, and provide even more accurate values for the
trajectories.
If
building floor plans
or structure (tunnel)

maps

are available
, the trajector
ies

will
be

plotted on
them

for
ease of observation and for corrections based on
the structure.

The laptop
can be

connected to a Wide Area Network
(WAN) modem for distribution of data
to other surveillance locations
.
The

Toughboo
k has an 80
-
pin reinforced port
-
replicator port
which
allow
s it
to be connected to a preinstalled set of peripherals,
such as a

wireless

modem.

The
Base Station Transceiver

will be developed by
TRX Systems. It

will be
a transceiver

for
receiving and interpreting information from the
Sentinel PLBs

and interfacing
with the
Command Station
. It will receive the node report
s

transmitted by the
PLBs
, and
have
a
microprocessor to control communications. The
Base Station Transceiver is
smaller than the
s
ize of a small cell phone.

The interface concept

design

is shown in

Figure
9

in prototype form
.
The base station user
interface will run on a ruggedized laptop. The interface will be capable of displaying current
and past location and sensor information for all mobile units on a building floor p
lan



if

Figure
8
. System Block Diagram

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12/4/2013


PAGE
12

available
. It will have 3D and 2D viewing options with natural
transitions among

views, for
example, click on a floor in the 3D move to change to 2D view.

A whole building wire
-
frame view of the building structure will be developed
with the
pos
ition of each responder indicated
. The building will include a scale
showing grid spaces of
approximately 10 feet in every direction
.
Positions will be shown for all responders,
if
an
alarm
is detected the
subject’s
marker will be
change
d

to red

and enlar
ged or blink
. Detailed
information on sensor data, etc. can be
seen

by clicking on an individual

marker
. Historical
path data can be shown if desired, for a selected individual
, group,

or
for
all mobile nodes.

The user interface will allow
the incident
commander to group
individuals into teams

(by task,
by engine,…)
that can be represented by different color or shape markers for ease of tracking.

We are experimenting with various 3D software packages for display of the data. A key is to
provide a syste
m of maximum effectiveness to field commanders


the GUI cannot be overly
complex
. I
t must make the information, especially alarms,

very easy to understand in an
operational
setting
. We will work with MFRI and DHS to achieve an effective design.

The
Base

Station
software
is critical for
displaying the position
s

of
responders

for
decisive
analysis and action.

To enhance
the

accuracy of indoor tracking, and
to
aid visualization
,

we
shall
develop algorithms and software to project the path of the
first respon
der

on pre
-
existing
maps
3

or
to create
maps created based on the
subject’s
trajectory.

The key features of this
task are
:
Map Matching
;
Map Building
; and
Outdoor Terrain
Mapping
.




3

The comma
nd station will have the ability to import maps and building floor plans as available at the incident.

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13

As shown in the prototype
design

in
Figure
9
, the softwa
re will plot the current location and
maintain a database of previous positions to produce a “trail” of
the path taken by the
first
responder
, if desired
.


The historical data will also be used to provide an incident playback
feature.

The program
shown in

Figure
9

was

designed using
the
Virtual Reality Toolbox
4

in
MATLAB

R14, which use
s

the
Virtual Reality Modeling Language (VRML)
for scene
modeling and display.
This display will be available
on the

Base Station
,
enabling
command

personnel to monitor locations within a building
. This will be of significant importance when
hazardous situations occur
. Information
from sensors

will also be displayed by the same
software
, using appropriate formats


e.g., for temperature (by color), so
unds (by type, noise,
voice),
radiation or biohazards (by color),
etc.

Map
b
uilding:
The second mapping algorithm take
s

precedence in the absence of floor plans.
While
first responder

positions are collected and plotted, a 3
-
dimensional floor plan is
autom
atically generated with a lifelike look and
feel


as shown in
Figure

10
.
This figure is a



4

We are using MATLAB to develop the software design and key functions. The commercial version of the software will be
compiled code that does not depend

on MATLAB.



Figure
9

A

part

of the path shown previously:

(
Left) Path
plotted
(in real
-
time)
on a floor plan
using

prototype

map
-
matching Virtual Reality software.


(Right)
3 dimensio
nal VR view of the unit moving on the floor plan
.

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PAGE
14

reconstruction (in real
-
time) of the path in
Figure
2

using JAVA3D objects to build walls and
corridors.


Figure

10

Building
internal
structure constructed by
JAVA3D

map
-
building software

for the path sho
wn earlier using data provided by the

INU.

This capability is important in constructing hypothetical models of the interior of a structure
.
As
individuals
make their way through
a

building
,

the software attempts to identify key
features such as stairwells, elevators, and hallways, and generates walls, floors and other
features, to define the structure of the building to aid the incident comm
ander viewing the
progress.


d.

Miniaturization of Prototype

Under
the
funding from MFRI, we have worked on
developing second generation
hardware
for the
Firefighter S
entinel system
.
The final design boards have been sent out and we will
have prototypes for
testing by mid
-
late April.

The motivation
s

for development of a generation two system are:

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PAGE
15



m
iniaturization



i
mproved
h
eat
d
issipation



addition of sensors



improved

c
ompass



replacing

INU to data radio wiring

with Bluetooth



r
eplac
ing

analog sensors with digita
l counterparts



c
onnector
u
pgrades

As shown in
Figure
1
, the Fire Sentinel Beacon in its new design has 2 pieces, the INU is
worn on the firefighters belt. The INU is now
connected to the data radio via Blue
tooth,
while
the
gener
ation 1 required a wired connection. With the addition of the Bluetooth wireless
connection, the radio can be connected in any convenient location so as not to interfere with
movement or other gear
.

The i
mproved INU
, which we plan to test at MFRI in May o
r June,

has

several new motion
detecting microelectronic sensors. These sensors are made possible with the advent of MEMS
sensors
that
have only
become

available
in the last several months
. The new INU
includes

a
MEMS three
-
axis accelerometer, two MEMS gyr
oscopes, and a 3
-
axis magnetic field sensor.
The data from the accelerometer will be used to identify individual steps taken by the subject
,
or other distinctive features of the motion
. The gyroscope provides the rate of angular change
of the user’s direct
ion. This information will be used to help calculate the direction of the
user’s line of progress. Data from the magnetic field sensors (compass) will
also be

used to
calculate the direction of the subject’s trajectory.


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PAGE
16

These sensors
are

controlled by a d
sPIC signal processing micro
-
controller chip. The data
obtained from the sensors, will be combined with unique algorithms to ascertain the precise
trajectory of
a subject in motion
.

Currently, the algorithm is optimized for walking

or stair
climbing in bui
ldings
, and largely relies on the gyroscope to track variations in direction.
With
the new hardware, t
he algorithm
can

be
enhanced

to more reliably determine whether the
subject
is crawling, running, etc.

The
role of the
magnetic sensor data will be incre
ased to provide another source of directional
data in addition to that obtained from the gyroscope. Errors in compass readings resulting
from nearby ferrous objects will be corrected by comparing the total local magnetic field
magnitude to that of the eart
h to recognize corrupted compass data.

The algorithm will be
coded using assembly language into the dsPIC. This microprocessor, which is optimized for
signal processing, will implement the algorithm, and output XYZ coordinates of the
subject
.
Error correct
ion algorithms will be developed to accommodate for sensor readings which are
momentarily corrupted.

The dsPIC will calculate the coordinates of the user, and
send them via blue tooth

to the
motherboard microprocessor. This information will then be incorp
orated into the node report
that the motherboard assembles, and output to the transceiver. The transceiver will then
transmit the node report, which includes the coordinates of the
subject to other team members.

In summary, the modifications we are making

to the system are:



INU
:

We are miniaturizing the INU and adding several new sensors so that
movements such as crawling can be tracked.

We are adding a Bluetooth module for
communications between the INU and data radio.

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17



Data Radio
: we are combining the
motherboard, GPS unit, and data radio onto one
board and adding a Bluetooth module for communications between this unit and the
INU.


d.1.

INU Improvements

Figure
11

and
Figure
12

show block diagrams for the first and second generation INU
,

respectively. Key improvements are the addition of z component to the magnetic field
magnitude and the second gyroscope.
These are critical components for tracking firefighters
when they are

crawling, or any other non
-
vertical mode of locomotion. The first generation
INU has limited capability to track a user when they are not vertical. For this reason
generation two has includes a vertically mounted MEMS gyroscope sensor and vertical axis
m
agnetic field sensor. These additional sensors are necessary for determining the direction the
user is crawling. The vertical axis magnetic field sensor will also assist in compensating for
compass bearing errors.

Analog sensors used for the INU
have

all
been
replaced with their digital counterparts. The
new digital sensors operate using SPI (serial periph
eral interface) which allows them to all
connect to the microcontroller via a common three wire bus. This allows PCB trace routing
space to be saved. In addition the digital sensors do not require buffers between their output


Figure
11
.

First Generation INU Block Diagram

Figure
12
. Second Generation INU Block Diagram

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18

signals and the microcontrol
ler. By eliminating these buffers, a large amount of additional
board space is saved.

The first generation INU is connected to the node controller via a 8
-
wire interface and was
considered to be a standard plug and play sensor. For generation two, the wi
red interface was
replaced with a Bluetooth wireless connection that is dedicated to communications between
INU and node controller. This benefits the user as it is less awkward, the risk of snagging
wires is eliminated, and time is saved because there i
s no additional connection for the user to
make while putting on the unit.


For the second generation INU all component sizes were reduced. The package type for all
resistors and capacitors was changed from 1206 (0.12” x 0.06”) to 0402 (0.04” x 0.02”). T
he
accelerometer was changed from a 15.4mm x 7.5mm leaded SOIC package to a 7mm x 7mm
leadless QFN package. The microcontroller was change
d

from a leaded

12mm x 12mm
TQFP package to and 8mm x 8mm leadless QFN package. The gyro was changed from a
26.5mm x

1
1.3mm evaluation module

to a leadless 8.2mm x 8.2mm LGA. The programming
and power connectors were also replaced with smaller counterparts. Total PCB dimensions
were reduced dramatically.
The critical dimension that defines how far the unit protrudes
from the body was reduced from 64mm to 14.3mm.



Old
INU

dimensions 13mm x 81mm x 64mm



New
INU

dimensions 37.6mm x 45mm x 14.3m
m

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19

Libraries have been created for new parts with manufacturing ease and
heat management in
mind. This involved defining solder masks openings and optimized solder paste stencil
patterns for each component. In addition
,

thermal vias were placed beneath the
microcontroller
. These vias

connect the exposed paddle of the QFN pac
kage to the ground
plane
and

a copper area beneath the IC to dissipate heat.

Assembly instruction packages have been created for the INU which include formatted
component centroid data file, silk screen and copper gerber files, solder paste gerbers,
format
ted bill of materials, and special instructions. This information is used by the board
assembler to place the parts.

PCB design was panelized and a border was added to meet requirements for automatic
component placement machines. Score lines were drawn a
nd cut so that assembled arrays of
PCBs can be easily snapped apart. Each board array contains 9 PCB’s. This not only eases
component placement but reduces the cost for each PCB.



Figure
13
. Second Generation INU Boards a) INU main board is worn vertically with back against fir
efighter’s belt. b) INU secondary
board inserts into the main board at silk screened rectangle and allows for tracking of firefighters in non
-
vertical orientations such as
crawling.

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20

Mounting holes were placed on the PCB to allow for easy and secure instal
lation in a plastic
enclosure. Prototype enclosure will be made from flame retardant ABS plastic with flame
rating UL94
-
0. Outer dimensions of enclosure will be about 2.5” x 2” x
0.8.

e.

Node Controller

The first generation node controller played the role
of reading data from external sensors
(INU, GPS, etc.), formatting data packets for transmission to the base station and sending the
packets to the data radio for transmission. The data radio and GPS were separate modules that
communicated with the node c
ontroller via a 8
-
wire interface. This modular approach was
taken in the beginning stages of the project so that different devices could be evaluated on the
same system. We were able to determine from testing data radios and GPS which were most
reliable.

Generation two combines the selected data radio and GPS module with the node controller on
the same PCB. The new node controller will still have plug and play ports but the connector
s
to these ports have been improved to provide extra reliability. The second generation node
controller has additional features including 4Mbit onboard memory for data logging, onboard
temperature sensor, onboard audible tone
generator for alerts, low bat
tery detection
with LED indicators, USB interface, alert
button to signal base station for help, and
dedicated GPS controller.

The microcontroller for generation two has
also been upgraded to a signal processing
microcontroller. This will allow for more

Figure
14
. Second Generation Node Controller

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21

e
fficient computations within the device.

As mentioned above, t
he first generation
node controller was

connected to the
INU via a 8
-
wire interface, where the INU
was considered to be a standard plug and play sensor. For
generation two, the wired interfac
e
between the two devices has been

replaced with a
Bluetooth wireless connection that is dedicated to communications between
the

node
controller
and
INU.

The new node controller will operate on four AA alkaline (or any chemistry over 1.3V/cell)
batteries w
hich will fit conveniently into PCB mounted plastic holders. All electronics on the
node controller PCB except for data radio will operate at 3.3V. The data radio will operate at
5V. Additional mounting holes on the PCB will allow for easy integration i
nto an electronics
enclosure.

f.

Future Work

Further development and testing of
the Sentinel

S
ystem is necessary in order to transition this
technology into a product
that is

available for firefighters across the country. TRx Systems,
Inc.

and partner compan
y Techno
-
Sci
ences, Inc., along with MFRI,

have applied for further
government funding from a variety of sources in order to continue this development.
Elements of the future work are outlined below.

Signal Processing

Remaining key technical challenges ar
e self initialization, (auto) calibration, and diagnostics.
In addition, algorithms that automatically recognize and adapt to varying motion types and
users must be developed.

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22

Specifically, we shall develop “multi
-
mode” tracking algorithms that can “rec
ognize” the
nature of the movement (walking, running, crawling, etc.) and select the appropriate signal
processing algorithm to compute location data for the context.

Mesh Networking

The mobile nodes in our sentinel system form a mesh network. By forming

a mesh network
data is allowed
to be routed (“hopped”) though other nodes if the nodes cannot form a direct
link with the base station. The ability to hop extends the range of the system. Our current
system supports a single hop operation, which means
if the data cannot get back to the base
station directly; it can be routed through one other node to get there. We are in the process of
upgrading the networking software to allow multiple hops, thus further extending the range of
the network. In our te
sting so far in up to 4 story buildings, a single hop has been sufficient to
obtain full coverage.

The mesh network also allows data to be communicated directly between mobile nodes on the
network, so that a node can know where all the other nodes in the

network are. Currently the
nodes do not store information from other nodes. The redesigned mother board has onboard
memory that will enable local storage of information on everyone in the network, so for
example, each node will store the last position o
f all other active nodes.

Sensor Information

The conditions a firefighter endures in a fire fight require extreme physical fitness. But in the
adrenalin rush of the fire, even a firefighter in peak condition can push

his body too far.
S
tress, heat
,

high

body

temperature and dehydration are all factors that can conspire to cause
critical injury. In fact, h
eart attack remains the leading cause of death among firefighters (44
percent of firefighter in
-
the
-
line
-
of
-
duty deaths are attributed to heart attack)
. A system that
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23

monitors and transmits a firefighter’s biometric data such as temperature, heart rate and blood
pressure, could detect a firefighter in distress and provide necessary and timely information for
their extraction.

Our motherboard microproce
ssor has the capability to receive data sent from blue tooth
devices. We will demonstrate the capability to communicate with off the shelf heart rate
monitors that send blue tooth signals.

The firefighters gear has become so good that they are not always
able to feel the external
temperature to know when they are in danger of overheating. Our INU hardware contains a
temperature sensor and in addition we will add a sensor into the firefighter’s jacket. Using
data from these sensors and an algorithm develo
ped and tested by MFRI in conjunction with
the University of Maryland Fire Protection Engineering Department, we will give the
firefighters (and incident commander) a time remaining warning when the firefighter enters a
high heat environment. The algorith
m computes exposure levels and estimates tolerable heat
levels based on a model of the insulating properties of the coat. As the temperature decreases,
for example, from controlling the fire, the time remaining will increase.

Information to Firefighte
r

Our current system collects information (position, sensor data, …) from the firefighters and
transmits it to the base station for display. We have not yet developed a system that allows the
firefighter to get information from the command station, for ex
ample, for alerts to evacuate, or
for egress direction, or for directions on most quickly get to a downed comrade. We will
develop and test a varying systems for getting this information to the firefighter. The systems
we intend to test range from simple

systems including LEDS in the SCBA mask to indicate
warning or direction, to preprogrammed text messaging and/or audio messaging (similar to the
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24

Magellan system in cars) to a blue tooth ear piece, to a fully functional HUD that would
eventually be built i
nto the mask. (See
Figure
15

for a commercially available system, that is
expensive
www.liteye.com
.) Even a simple communications system will allow the incident
commander to get important in
formation quickly to the person or group that needs it.


Figure
15

Liteye HUD mounted on a helmet. The viewer is “transparent” enabling the us
er to see objects ahead.

Getting user feedback on these communications systems is critical. We have seen devices
with nice displays that we have been told will not be able to be seen in a smoke filled room, or
with audio that we are told could not possibl
y be understood in the noise of a ranging fire.
Testing our systems with MFRI and local fire departments will be a valuable step in coming
up a workable design.

We expect that this system will be an add
-
on module to our main tracking device

Testing

Furth
er testing and customer feedback are crucial. To accomplish this we
will continue to
work

with the Maryland Fire and Rescue Institute (MFRI). With the help of MFRI our
technology will be tested successively more difficult operational scenarios. First th
e system
will go through trials in the burn building and smoke maze with fire fighter trainees in full
turnout gear. Once these tests are completed successfully and feedback is aggregated and
addressed, MFRI will arrange for local fire departments to beta

test the system and provide
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25

feedback. In parallel, we will test the system in buildings that are complex from the point of
view of transmission of radio signals. Test results and user feedback from will be a major
driver for rapid improvement of system.

Testing the system in a variety of different scenarios
will help to assess and eliminate failure modes. Feedback from users will be rapidly turned
around to improve system usability by the customers.

Certification

We have begun to look into certificatio
n testing. At this point there are no NFPA standards
for location and tracking technology but our plan is to take what we can from the NFPA 1982
Standard on Personal Alert Safety Systems. We have spoken with Steve Sanders at The
Safety Equipment Institut
e (SEI) who has made us aware of a developing electronics standard
NFPA 1800 that may also have relevant tests but that will probably not be complete for
another couple of years. In the meantime, we will follow the development to assure we are
prepared fo
r any new testing. SEI is a local company that provides third
-
party certification
programs to test and certify a broad range of safety equipment products. The Safety
Equipment Institute headquartered in McLean, Virgina. SEI's certification programs are
accredited by the American National Standards Institute (ANSI) in accordance with the
standard, ISO Guide 65, General Requirements for Bodies Operating Product Certification
Systems.


We will have the system certified for Intrinsic Safety (UL 913). We pla
n to sub this
testing to Intertec Testing Services in Courtland NY. This is also one of the labs used by SEI
in NFPA 1982 certification testing. We plan to initiate certification design reviews before
about 6 months into this effort to ensure that ther
e are no clear issues with our electronics and
enclosures that need to be addressed before testing can begin.

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26

Manufacturing

We have identified and met with a subcontractor that we will be using for enclosure design
and manufacture, EG&G in Ijamsville, MD.

They have engineering as well as full CNC and
conventional machine shop facilities to support our effort. In addition, they have experience
with developing for and going through certification testing. We have identified companies to
make and assemble t
he circuit boards. Advanced Circuits (
www.4pcb.com

), who we have
worked with in the past, will make the boards and Screaming Circuits
(www.screamingcircuits.com
)

will

assemble them.


Both companies will do small runs and
are also capable of running productions quantities. We plan to do final assembly and system
testing in house for quality control purposes.