1.0 Challenge Analysis

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2 Νοε 2013 (πριν από 3 χρόνια και 7 μήνες)

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1.0 Challenge Analysis




As an engineering academy, we are taught that one of the most important steps to building a
robot is to understand the purpose and restrictions of the design. Only after we establish the
customer’s needs can we create a robot that will perform the ta
sks at hand. Therefore before
we began brainstorming ideas for the robot

(see A
ppendix 3.2.2
-
3.5.2b
)
, we analyzed the
playing field

(see Appendix 1.1 Table 1.1)
, identified the various scoring options

(see Appendix
1.2 Table 1.2)
, and established our prel
iminary offensive and defensive strategies

(see Appendix
1.3 Table 1.3)
.


Total Recall challenges our team to accomplish a variety of tasks

(see Appendix 1.0 Table
1.0)
. First, the robot must be able to transport the mobile recall trailer to the MRT d
ock which
will then activate the Gadget Transport tube. Once the process flow is open, the spotter can
place the gadgets into the scanning tube. Gadgets must be collected and transported to the
Shipping Center, from there the defective gadgets are return
ed to the recall center and the
good gadgets are sorted by color into the packaging tubes. In addition to collecting,
transporting, and packaging gadgets, the robot must be capable of retrieving gizmos from the
pallet and place them in the packaging cones

before sealing them for shipping. Any defective
gadgets or gizmos that enter the manufacturing center must be recalled.

1.1


Playing Field Analysis


The field is composed of 4 separate
but identical
sections. There are no obstacles

for the
robot to over
come

and
the playing field
is an entirely flat surface. This calls for the design of the
r
obot to be compact and agile
.
Th
ere are two processing areas on opposite sides of the field,
the right being gizmos (golf balls) and the left being gadgets (magnet an
d non
-
magnet eggs).
The recall area and data port interface are near the driver’s area and the start location of the
robot. The robot must also be able to place a
n

agility cone in its processing area which is 18in.
off the ground, and also be able to move
the mobile recall tray across the field.


The design of the playing field is focused more on precision and vertical movement than
power and agility, with its small work space and the height difference for the processing of
product. The spotter may only

interact with the gizmos and are confined to a work area in the
center of the field.

1.2

Scoring Option Analysis


With the many ways to score points, we originally wanted to go for the gizmos and package
them.


We saw that the gizmos gave the most points
per object.


Unsealed gizmos were 10
points each and sealed ones were 20 points.


To add on to that, if we could package them, we’d
get an extra 50 more points.


The original design of our robot only allowed us to collect and transport
magnetic eggs
.
However we learned trying to release the magnetic eggs into the gadget package was
extremely diff
icult.


We soon discovered that the robot could collect and package the gadgets
much easier and more efficiently. Even though the gadgets only gave 2 points e
ach for being
collected and 3 points each for being packaged, the robot could collect the gadgets way faster
than the gizmos.


The scorecard shows our potential points for our robot when testing.


When
we tried for the gizmos we got around 2100 points.


No
t bad right?


Well when we did a trial
run just going for the gadgets, we got a nice total of 3000.


While gizmos earned more points
per item, they were mo
re difficult
to collect, transport, and release and in the long run earned
us fewer points
than the m
uch easier task of collecting and packaging gadgets.

1.3

Preliminary Offensive / Defensive Strategy


Since there is no interaction with other team’s robots, we don’t have any defensive
strategies.


Our offensive strategies are quite simple.


First,
we’ll try to read the data port as
quickly as possible.


Second, we will collect and package gadgets as fast as we can.


Finally, we
will try to make sure that we will have little to zero defects to maximize our score
.

2
.0 Functional Requirements

(see Appe
ndix 2 Table 2.0)



Next we focused on the functional requirements of what the robot must accomplish during
the th
ree minute window of operations, taking into consideration both

the order in which they
should be accomplished in order to achieve the hig
hest degree of six
sigma

and the constraints
placed on us by the customer. We identified four functions our robot needed: movement
around the playing field, grasping or picking up the game pieces, transporting the game pieces
without dropping

them
, and d
epositing the game pieces in the appropriate scoring area.

2.1

Movement


The primary requirement for the robot is movement.


It has to be able to maneuver around
the playing field in order to complete any of its other tasks.



To increase the mobility
of t
he
robot

we decided to use a

wheel

with a larger diameter

so that it travels a greater distance per
rotation

(
see calculations in Appendix 3.0 Table 3.2.3
)
.


Since the playing field is free of
obstacles our front wheels could be designed to have a tight turning radius and ability to
maneuver easily throughout the playing field.

2.2

Grasping


Another functional requirement of the robot is that it needs to
have a grasping mechanism
for grasping the cones.


Since our scoring strategy does not involve going for the Gizmos or the
lids for the cones, the grasping mechanism can be designed specifically for the cones

(see
Appendix 3.4.2b Figure 3)
.


The grasping m
echanism's arm

needs to be able to reach high
enough to place the cone in the Gizmo Pack and Ship center as well as be able to flip the cone
over to put it in right
-
side
-
up.


The actual grasping mechanism itself must fit the cone, which
has slits.


The sli
ts in the cone mean that we can either use them to lift the cone, or we must be
aware of them so as to not get the cone stuck on the grasping mechanism because of the slits

2.3

Transporting


Another functional requirement of the robot is a transportati
on mechanism for the Gadgets.


It must be able to catch them as they fall out of the Gadget Scanning Tube, hold them securely
while it moves them to the sorting area, and then deposit them into the sorting area.


By using
the robot to transport the Gadgets
, we solve the problem of having to use the Mobile Recall
Trailer, which we would have trouble dumping into the sorting area.

2.4

Depositing


The last requirement is a way to deposit the gadgets into the manual sorting area and collect
any waste produc
ts.
There is a sweeper to direct any waste that falls onto factory floor back
into
the
product recall center, and a trigger mechanism (
dump truck
, trap door, etc.) to release
the gadgets from a storage compartment into manual sorting area

(see Appendix 4.
3.1 Table
4.3.1)
.


By using these mechanisms we provide clearance over the wall of the manual sorting
area.

3.0 Conceptualization of
Robot Design

(see Appendix 3 Table 3)




The next step in the engineering desi
gn process is conceptualization:

researching,
brainstormin
g, and sketching. We broke

the robot
down into its

major components: chassis,
wheels, arm, and grasping mechanisms, discussing possible design for each component

(see
Appendix 3.4.2a)
. To further focus our brainstorming, we ide
ntified the requirements of the
given components.
To identify the requirements we asked ourselves: What are

the important
functions or objectives each component much achieve were
, what materials are

available, and
what constraints or limits must be taken into consideration? By understanding what we want
the robot to be able to accomplish, we were able to design the different elements to achieve
each task.


First we sketched

ideas

and built
three
-
dimensiona
l

models using Lego’s and K
-
Nex. The
models let us visually understand how each component of the robot would be able to move. In
addition, the models further helped us understand the steps necessary for constructing the
robot. Taking the time

to create three
-
dimensional models was important, simply because
anything is possible in a two
-
dimensional drawing. You can design a robot on paper in only five
minutes but executing the actual design may take over five weeks, and time is something we
ca
nnot replace. We could not afford to realize major design flaws a week before competition.
Since we also have limited supplie
s, it is necessary that we do

not

waste materials on a bad
design. These functions and constraints were then used to analyze eac
h design option before
making a final decision.

3.1

Chassis

3.1.1

Requirements


The function of the chassis is to support the weight of the robot, provide straight edges
necessary for the wheels, be sturdy yet lightweight, and provide enough room to at
tach the
various robot components. After analyzing the playing field we knew we needed a tight,
compact robot capable of maneuvering within a limited working space.

3.1.2

Design Options

3.1.3

Pros / Cons

3.1.4

Final Decision

3.2

Wheels

3.2.1

Requirement
s


The number of wheels and their placement will determine, to a large extent, the overall
mobility and stability of our robot. Our back wheels control our speed and turni
ng radius.

Our
front wheels should be smaller, mounted below the chassis, enhan
ce the stability of the
chassis, produce a tight turning radius, and produce very little drag. In order to make the
decision we focused on the playing field and demands our robot would face. The playing field is
open, without any obstacles our robot will

need to maneuver around or over.

3.2.2

Design Options

Golf Ball Wheels

(See Appendix 3.2.2 Figure 1)


The golf ball wheels are a design we have used in the past. The golf ball wheels are wedged
between the open ends of two PVC pipe elbow and a T join
t. This design produces a very tight
turning radius with very little drag. However, one of the

drawbacks to this design is

the
tendency for the golf balls to come out

given the game pieces this year are golf balls we
decided any lost wheels could be cons
idered debris and reduce our overall sigma.

Shopping Cart Wheels

(See Appendix 3.2.2 Figure 2)


The shopping cart wheel design provides even distribution of weight, prevents the robot
from tipping over while also allowing a tight turning radius.
However, the shopping cart wheels
are difficult to assemble. The difficulty in assembly is worth the effort if there are obstacles to
go over because the shopping cart wheels are excellent at traversing obstacles, however, there
are no obstacles on the co
urse this year, rendering it pointless to spend extra time making
them.

PVC Pipe
Skids (
See Appendix 3.2.2 Figure 3)


Inspired by the skids on a sled, PVC pipe elbows function as

front "wheels" in a sense.


The
skids keep the otherwise pointed edges of

the robot from dragging on the floor, allowing it to
move more easily and have a tighter turning radius.

There is very little friction and the skids
can be placed to evenly distribute the weight of the robot.

The skids are also very easy to
make. Since

the robot does not have to g
o over any obstacles, the skids are the best option.

3.2.3

Pros / Cons


Both t
he front
and back wheel designs have

pros and cons. The pros of the f
ront wheel
design include
les
s friction on the carpet and

movement

that

is n
ot jagged. The con of this
design

is

limited movement from left to right. The pro of the back wheel design is

that

it has a
lot of power behind it. The con of the back wheel design is that friction tape is needed to
prevent the wheels from spinning in plac
e.

3.2.4

Final Decision


Gaining knowledge from previous years’ wheel design, we gathered an understanding for the
type of wheels compatible with different obstacles. So, when we found out that the playing
field would be all carpet, we knew the PVC skid design was ideal for our fr
ont wheels.
PVC skids
provide the least amount of friction on the carpet. They weigh the least and make a gliding
effect across the carpet. We could also position the PVC pipe skids at the outer edges of our
chassis which would help distribute the weight e
venly and prevent our robot from tipping over
when transporting large numbers of gadgets.
The decision to use the PVC skids was also
influenced by the design we chose
to collect any debris from the factory floor.


For the rear wheels we debated between a 10” or 14” diameter wheel. In order to make an
informed decision, we calculated the circumference to determine the distance traveled per
rotation.
Explain the testing procedures.

From our testing we learned t
hat the combination of
the small motor and 14” diameter wheel produced the greatest velocity.


We also evaluated the large and small motor to determine which produced the greatest
velocity and torque. Although the small motors had more revolutions p
er minute and would be
faster, the large motors

produced about three times
more torque.
Given the challenge of
transporting the weight of the robot along with over a hundred gadgets at once, we
determined our best decision would be to use the larger motor

even if we had to sacrifice
overall speed.

3
.3

Gadget Collection and Transport

3.3.1

Requirements


The gadget mechanism should be designed to maximize the number of gadgets (golf balls)
that can be collected and transported at one time. While the mob
ile recall trailer can be used
to collect and transport gadgets to the gadget sorting area, the spotter is not allowed to
remove the gadgets from the trailer. As a result our robot will then have to remove the gadgets
from the trailer one at a time, or fi
gure out how to flip the trailer over without sending gadgets
all over the factory floor. If the trailer is flipped over, will the robot be able to turn it right side
up so the spotter can return any defective gadgets to the recall center.

3.3.2

Design
Options


Trap Door
(See Appendix 3.3.2a Figure 1)


For our initial design of the carrying system, we wanted to keep it very simple. We used a
simple box to hold the golf balls as we collected them.

Doggie Door
(See Appendix 3.3.2a Figure 2)


This

design again is a simple box but with

the hinged door on the side similar to a doggie
door.


Angled Dumpster

(See Appendix 3.3.2a Figure 3)


This led us to our final design, with the hinge
d door is

still on the side but, with the bottom
slightly ang
led so that gravity will help the circular golf balls roll out of the door into
the scoring
area.

3.3.3

Pros / Cons


While each design served the purpose of collecting and transporting large number of
gadgets, only one allowed for a controlled release
of gadgets into the sorting area. The first
prototype of the flat box with the hinged trap door resulted in the trap door opening
prematurely due to the weight of the golf balls.
Upon testing the doggie door design, we
concluded that while we could cont
rol the opening and closing of the door, the golf balls would
simply sit motionless on the flat bottom of the carrier. Again, if we can’t release the golf balls
into the scoring areas the design is not practical.

3.3.4

Final Decision


The final prototype of the angled dumpster solved the problem of the gadgets remaining
stuck within the box. The sheer weight of the golf balls and the angled bottom directs the golf
balls out of the dumpster and into the sorting area.

3.4

Gizmo Grasping

Mechanism

3.4.1

Requirements


Of the three types
of objects available to collect

(
the 9
” agility cones, the Gizmos, and the
lid)
, the agility cone is worth
most

points and is essential to packaging and sealing the
G
izmos.
Therefo
re our team

has decided to focus primarily on getting the cones. Because of this, the
requirements of the Gizmo Grasping Mechanism are as follows: 1) it must grasp the cone
without dropping; 2) since the cone has slits, the mechanism must not get caught in the slit
s;
3)
(optional)

use the slits to grasp the cone. In order for a design to be considered for use on
the final design, it must meet
at least requirements 1 and 2
.

3.4.2

Design Options

Grasping Mechanism #1
(See Appendix 3.4.2 Figure 1)


Grasping Mechani
sm #1 was designed as a clasp that opens moving side to side.


There is a
motor at the base that allows it to rotate.


There is a small cutout in it that allows for the cone
to fit in it.


This design limits what can be picked up, because of its rigid shap
e.

Grasping Mechanism #2
(See Appendix 3.4.2 Figure 2)


Mechan
ism #2 was designed with the int
ent to pick up the agility cones and the eggs. It
would be made of plastic or metal with a rubber
-
like grip to increase the friction. There is a
groove in t
he top for the eggs to be picked up one by one. It can open and close like a claw,
and has a rotating axis at the base of it. The advantage of this design is that it is efficient in
gripping, but cannot pick up large quantity of gizmos at one time.

Gra
sping Mechanism #3
(See Appendix 3.4.2 Figure 3)


Mechanism #3 was used in the final product. The design uses an optimized gripper that
utilizes the slits on the cones. The skewer

rotates to allow an opening and the gripper raises
and lowers to allow

a stronger grasp on the cone.

Grasping Mechanism #4
(See Appendix 3.4.2 Figure 4)


Mechanism #4 was designed as a barbed fork that will be able to open and close in order to
pick up the cones and gizmos. It also rotates around the base so that it can pick them up no
matter how they are laying. This idea is practical in that it can pick

up any of the objects,
however, it

could also easily drop them.

Grasping Mechanism #5

(See Appendix 3.4.2 Figure

5
)


Mechanism #5 is designed to grip the object using magnets for fingers. The gri
p
pers move
up and down and rotate side to side.

Graspin
g Mechanisms #6

(See Appendix 3.4.2 Figure 6)


Mechanism #6 was designed as a pincer
-
like device. The mechanism should be made out of
plastic or wood and the support should be made out of wood while the forklift part should be
made out of either coat
hangers or wood. The benefit of having a plastic grasper is that it
requires less energy to move, however it is not as strong as a wood grasper and may or may not
fall apart during the competition. The wood grasper is stronger and less likely to fall apa
rt
during the competition but requires more energy to move and more force to support. A coat
hanger would be easy to move but would also be easier to bend and break. The benefit of
wood support is that it provides enough support to handle either design f
or grasper and forklift.

3.4.3

Pros / Cons


After close examination of each design for the Gizmo Grasping Mechanism, it was discovered
that many of the designs are very similar to each other.
Designs #1, 2,5 &6 involve creating a
grasping mechanism th
at opens and closes around the agility cone or egg while designs #4 and
5 take advantage of the slits on the agility cones in order to lift and rotate the cones.

3.4.4

Final Decision


After long hours of debate, we chose to construct a grasping mechani
sm similar to design #2.
The “fingers” of the grasping mechanism would be constructed from the lightweight plastic and
shaped to fit the circumference of the agility cone. In order to mechanize our grasping
mechanism we used the hand from a hydraulic rob
otic arm
(See Appendix 3.4.4 Figure 1)
for
inspiration. The plastic fingers would be attached to a metal plate by screws
. Rubber bands
would provide tension to keep the fingers closed. When a servo pulled back on the bicycle
brake cable t
he fingers
would
open
, when the bicycle cable was released the fingers would
close
tightly
around the cone.
The metal plate would be attached to a second servo which
would allow the entire grasping mechanism to be rotated.

3.5

Arm

3.5.1

Requirements


Unlike challenges in the past which required the arm to reach upwards of 3
-
5’ in height, the
game this year requires a maximum reach of 18
-
24”. The arm must be able to reach agility
cones, eggs, and frizbees placed on the floor and deposit them into a sta
nd 18” off the ground.
In addition, the arm must remain within the 24”x24”24” size constraints, be easy to construct
and control, and be operated by a small motor.

3.5.2

Design Options

Two Stage Extendable Arm

(See Appendix 3.5.2 Figure 1)


This desi
gn has pulleys on the
joints

of the arm, allowing one motor to double or even triple
the arm length. This extension will allow the grasping mechanism to reach the cones
on the
floor as well as place the cones in the Gizmo Packaging Center
. The arm would
be constructed
from PVC pipe and a threaded rod, which acts as the pivot point.
A second segment of PVC
would be attached at the “elbow” allowing the arm to double the arm length.
The pulleys
would be made out of plastic. While this arm design allows th
e claw to reach the cone while
conserving space, it is at a disadvantage since we only have one small motor at our disposal
(the other one designated for
operating the

gadget transport mechanism). Since this design
cannot pivot at different angles it grea
tly restricts the maneuverability of the arm
.

Single Stage Arm
(See Appendix 3.5.2

Figure 2
)


The single stage arm design is simple to create and can allow for over 270 degrees of
rotation if constructed properly. In additi
on to being easy to construct,
the arm design is light
in weight and can be operated using the smaller motor. With appropriate tension in the pulley
belt, the arm can be precisely controlled by the operator; giving us an advantage when placing
the cones o
n the storage areas. The main limitation to such a design is the limit to the overall
reach it can attain.

Chain and Sprocket

Forklift
:

(See Appendix 3.5.2 Figure 3)


A rod would hold a motor perpendicular to itself, and parallel to the body of the ro
bot. The
motor would turn a chain, which would either lower or raise the carriage/lever. The pros of this
mechanism include: good mechanical advantage, sturdy, simple. The cons of this mechanism
include: difficulty making gears, and difficulty balanci
ng the rod to hold the motor.

Rack and Pinion

Forklift
:

(See Appendix 3.5.2 Figure 4)


A rack would support a gear which would connect to our lift enabling it to move up or down.
There are no pros for this due to the fact we were unable to prototype
it. The cons of this
mechanism include: its complexity, the inability to mechanize, and the inability to connect the
lift to the rack which would raise it.


Pulley System Forklift:

(See Appendix 3.5.2 Figure 5)


A motor, M, would act as a “reel” and

wind a string which runs over a pulley and connects to
our lift. When the motor turns one direction the string winds up lifting the mechanism and in
the other direction it un
-
winds the string lowering the mechanism. The pros of this mechanism
include:
it is simple, it shows consistent lifting force, it is sturdy and it has good mechanical
advantage.

3.5.3

Pros / Cons

3.5.4

Final Decision

4.0 Building the Robot


4.1

Safety Concerns


Safety is important for building a robot because
without

safety rules, people could get hurt.


Power tools are useful for drilling and sawing quickly, but they are also very dangerous devices.


There is a power tool safety

test that all robotics team members at SVTA have to get 100% on in
order to use any power

tool.


This test is basically common sense on power tool safety, and
what to do if an accident occurs.


Our OSHA certified safety instructor William White

instructs
and teaches

our students

how

to

prevent any accident from happening in the first place.

M
r.
White identified four basic areas in which safety violations can occur; 1) use of safety
equipment 2) poor communication 3) improper use of tools or use of defective tools and 4)
hazardous work environment.


One of the most important and often forg
otten safety rule to follow is
the use of safety
equipment. Shades Valley stresses the need for wearing eye and ear protection whenever using
power tools.
Ear protection is required when using the band saw, miter saw, jig saw and miter
saw. Prolonged expo
sure to loud sounds can cause permanent damage to one’s hearing.
Safety glasses are required whenever working with any tools.


The lack of good communication can lead to injuries in any work environment. Telling others
what you are doing can keep th
em aware of circumstances in the work space and help them to
make better decisions upon what to do and where to move.

This includes communicating to
other students in the vicinity that a power tool is about to be used. A student unaware is a
student unpr
otected. Even though students are trained and tested on power tool safety,
s
tudents are required to be supervised by an adult whenever

operating

power tools.


When using a tool the safest way to use it is the way it was designed to be used. If one d
oes
not use a tool in a proper manner it can malfunction, break, or cause an unsafe work
environment.

To ensure tools are in proper working order, we have our OSHA trained
instructors inspect our tools at the beginning of each season. Currently our team
does not have
the tools or training to be able to cut metal safely. Thankfully the students in our welding and
electrical programs have the tools, training, and proper supervision from OHSA trained
instructors..


Hazardous work environments are very

dangerous. Leaving sawdust on the floor, tools out of
place, and extension cords out could cause someone to slip, fall, and seriously injure
themselves. Cleaning up a work area is the only way to prevent the hazards.

Safety Posters are
posted around the
work areas to remind students to follow all established safety procedures.

4.1

Chassis

4.1.1

Specifics


The chassis is constructed from the polypropylene plastic and serves as the center of the
entire robot. Our first choice of material was the 1/8” p
lywood, however we felt it was too
flimsy to withstand the rigor of the competition. The plastic is light in weight while providing
the rigidity necessary to support the weight of the robot. Given the tight confines of the
playing field, we knew the robo
t needed to be small and compact in size. To determine the
exact dimensions, we created a blueprint identifying where each component needed to be
placed. We decided a 16”x12” rectangular base would accommodate the four motors, VEX
cortex, arm, and gadge
t collection mechanism.

4.1.2

Challenges


The original layout for our chassis involved our gadget collection mechanism to be mounted
on a stand

thereby providing room underneath to place the VEX cortex and battery. Later we
discovered that the stand interfered with our robot’s ability to collect
gadgets. As a result we
had to mount the gadget collection mechanism directly on the chassis. Space on the chassis
was now at a premium and our conclusion was to of place the small motor operating the
gadget collection mechanism under the chassis.

4.2

Wh
eels

4.2.1

Specifics


The wheel is made out of ¾ inch plywood

and is 14” in diameter.

We determined a larger
diameter wheel produced a faster robot since the robot travels a greater distance per rotation
of the motor. Instead of constructing small fr
ont wheels, we created skids from PVC pipe
elbows.

The PVC pipe skids would be mounted to a
Plexiglas

frame designed to collect any
game pieces that may fall on the factory floor and return them to the recall area.


4.2.2

Challenges


You would thin
k attached round wheels to a rectangular base would be easy

but we
encountered several problems. Since we received new motors this year our first challenge

was
to
create new support stands to attach the motors to the chassis.
Even though the new design
i
s almost identical to the support stands we used last year, we had difficulty keeping the motor
shaft perpendicular to the chassis. Because the motors could flex up and down, our wheels
would “wobble” back and forth and we were unable to drive in a straig
ht line. To solve this
problem we incorporated straps made from the metal tape to keep our motors “locked” down
in place.


Another problem was the
lack of traction which caused our wheels to spin in place.

The
cause of the slipping was due to the
walls of the “gutter guard” being too high

as a result the
wheels
did

not
always
touch the ground. As a solution, we shaved off
1/8” o
f the
plexiglass so
the wheels are now

able to touch the ground.

We also discovered that as the robot moved, the
positio
n of the PVC pipe elbows would slide toward the center of the robot. When this
occurred the robot

would be
come

unstable and tilt over when it came to a
n abrupt

stop.

By
screwing the PVC pipe elbows into position we produced a more stable chassis and crea
ted a
much smoother ride. Our final touch was to replace the friction tape with the rubber from the
b
icycle inner tube to su
rround the edge of the wheels and

create more traction.

4.3

Gadget Collection and Transport

4.3.1

Specifics


The material for

the dumpster is the 1/8” plywood. We used this material because it is light
and durable. Since we were only give
n

4 angled brackets we created our own from the thin
aluminu
m sheet. The overall dimension

of our dumpster is 11.25” long, 10” wide and 11.5”

deep. The bottom of the dumpster has an angled slope that makes it easy for the gadgets to
slide down. The reason it is so large is because it would be able to hold more gadgets which
would give us a scoring advantage by reducing the number of trips our
robot has to make
between the gadget process tube and the gadget sorting area.
During Mall day we were able to
collect and transport 115 golf balls easily in one trip.
The dumpster also has a flap that releases
the gadgets at a steady rate. The flap is c
onnected on two hinges. The small motor that is under
the chassis
controls the opening and closing of
the flap.

4.3.2

Challenges


I
n the beginning we had multiple problems. One of them was that the dumpster itself was
too high
and could not drive under
the gadget process flow tube. If we can’t collect the gadgets
then we can’t score. Thankfully all we had to do was to remove the support
stand
.

Unfortunately mounting the dumpster directly on the chassis created another problem. Now
the dumpster was too

low to release the gadgets in the sorting department. This led to the idea
of putting a 1x4 under the base of the dumpster to elevate
the dumpster
to the right size for
releasing the gadgets

while still allowing it to fit under the gadget process flow tub
e
.


While the majority of gadget land in the sorting compartment, there was still a ten
dency for
gadgets to fall on the floor. Because of this, we’ve created a
n angled

ramp

with guard rails

that
would guide the gadgets into the sorting area more effic
iently. Sometimes, the gadgets would
get stuck inside of the dumpster, so we must ram the robot to the edge of the sorting area to
have the gadget return to flowing out of the dumpster.
Going into the competition our

major
potential problem is if the str
ing that releases the flap wounds around the motor shaft. Then
the dumpster won’t be able to release the gadgets.

4.4

Gizmo Grasping Mechanism

4.4.1

Specifics


The “skewer”
resembles a two pronged fork

and is made from the galvanized sheet metal
.
The
teeth are 7” long and 2” wide and bent to match the angles of the slits found on the “gizmo
package” or agility cone. We are able to “grasp” the gizmo package by inserting the tines of the
fork inside the slits of the agility cone. Friction tape has been
added to the tines to reduce the
likelihood of the gizmo package from slipping off the tines

during transport
. Once the agility
cone is “skewered” the arm raise
s

the
cone

to a height of 20 inches
. The cone is then rotated
into position by a servo, the ar
m lowers the cone into place and the
robot simply drives
backward releasing

the cone into the gizmo packaging center
.
Since the skewer is made from
the galvanized metal, it is also able to pick up the magnetic gizmos.

4.4.2

Challenges


The “skewer”
design has two tines to go into the slits of the agility cones and is made from
the galvanized metal. The metal provides enough rigidity to prevent them from being bent and
yet is lightweight. The design is easy to attach to the arm design in order to ra
ise and lower to
the appropriate height. Its light weight means it can easily be rotated using a servo motor in
order to place the agility cones in the scoring area. It also has the bonus of being capable of
picking up the magnetized Easter eggs.


Since all the

motors were designated elsewhere, we had to rely on a servo to rotate the
skewer. Originally we believed the servo would have the ability to rotate a full 180
0
. However
it wasn’t until we were to the programming stage that we learned the se
rvo is only capable of
rotating a total of 127
0
. While we could rotate the cone, we couldn’t achieve enough of a
rotation that would allow our drivers to deposit the cone into the gizmo packaging center. To
solve this problem we

attached a metal plate to

the servo and then attached the skewer to the
plate (see Appendix Figure). As a result we were able to achieve close to 180
0

of rotation
.


In order for our design to be effective the driver’s must have plenty of practice in order to
“grasp”, tra
nsport, rotate, and deposit the agility cone without dropping. The biggest challenge
comes in “skewering” the cone since the driver is
essentially

“blind
” and must rely on the
spotter to provide direction.
However, there are three main problems with this

design: 1) if the
cone falls off, the robot may not be able to pick it back up and 2) we are unable to collect the
non
-
magnetized Easter eggs and 3)
the skewers tendency to fall off the servo
---
the small servo
screw tends to work lose as the plate rotates

back and forth.
While it is not a perfect design,
we feel given the difficulties with the two other designs we tried, it at least will allow us to
achieve some success.

4.5

Arm

4.5.1

Specifics


The arm consists of a small motor and two
IGUS

slides

on
e
IGUS

slide is stationary and is
attached to a 1x4, the other
IGUS

slide is inserted into the grooves of the first slide and is free
to slide up and down. A string is tied to the end of the free
IGUS

slide (serving as a lower limit)
and is fed through a
hole at the top of the attached
IGUS

slide (serving as an upper limit).
A
PVC pipe is attached to the top of the 1x4 and acts as the fulcrum allowing the pulley to raise
and lower the arm effortlessly.


By utilizing the two
IGUS
slides together we c
an easily fit within the 24” height constraints.
Lowering the
IGUS

to its bottom limit allows us to capture the agility cones off the floor, raising
the
IGUS

slide to its upper limit allows us to place the agility cone into the gizmo packaging
station.

4.5.2

Challenges


5.0 Testing and Evaluation

pages

5.1

Mall Day Results

(see Appendix 5.0 Table 5.0)

5.1.1
Gadget Storage & Transport:


The Gadget Storage and Transport mechanism was originally 23 inches high.


However, at
Mall Day we learned that the Gadget Process Transport tube was only 17 inches off the
ground.


Our storage and transport mechanism was 6 inches too high.


To fix this, w
e removed
the mount and placed it on the base of the chassis and moved the motor and pulley to
underneath the chassis.


This resulted in a mechanism that could fit under the flow tube but
was too low to release the gadgets into the sorting area.


Placing a

1x
4 board underneath the
gadget storage compartment allowed the mechanism to release the gadgets into the sorting
area, as well as fit underneath the flow tube.


Mall day also informed us that when the
compartment was totally full of golf balls, the weigh
t sometimes prevented the trapdoor from
opening.


To compensate, we

remove
d 1/2
” from the height of the trap door and place an
angled plate to direct the balls into the sorting compartment.

5.1.2
Data Port:


We learned that in order to learn which co
lor Gadgets are defective, all of the data ports
must be accessed, not just the first two.


Since we have changed our strategy, this is extremely
important.


Whereas before we could just go for the cones until the defective

Gadgets are
automatically reveal
ed, this strategy is no longer viable because our strategy is now to go for
the Gadgets the entire time.


We now need to interface with the data port.

5.1.3

Gizmo Transport:


Our Gizmo Transport Mechanism could pick up the magnetic Gizmos, but it had
difficulty
placing them in the cones.


It could not pick up the non
-
magnetic Giz
mos at all, and if the
magnetic

Gizmos happened to be defective during a round, we could not score any points from
Gizmos at all.


This meant that Gizmos were not a viable scor
ing strategy.


We fixed this by
modifying our strategy to go only for Gadgets.

5.2

Proposed Changes

6.0 Driver Strategy



At the beginning of each round, our first priority will be moving the mobile cart to the
information port since the gadget assembl
y line cannot be activated until this is accomplished.
Next will be having our robot interface with the Data port in order to determine which golf balls
are defective. By learning the color of the defective golf ball early, we can ensure that our
spotter

will not introduce defective materials into the production line. The design of our gadget
collection device will allow us to transport 100 or more gadgets at once, time will not be wasted
having to pick the golf balls up off the floor or flipping the mob
ile cart into the gadget sorting
area. After releasing the gadgets into the sorting area we will wait for the spotter to return any
defective materials to the mobile cart so our robot can return them to the recall center thereby
increasing our degree of S
ix Sigma. Hopefully we will have enough ti
me to make a second trip
to
gather more gadgets.
If it looks like we do not have enough time to make a second trip, then
our spotter will begin

6.1

Practice


During practice the majority of our problems were

due to mechanical problems

wheels not
gathering enough traction in order to move, “skewer” falling off when we tried to flip the agility
cones, unable to release the gadgets.

6.2

Potential Problems


Our number one concern is with our gadget collecti
on and transport mechanism. If the
drivers aren’t careful, they could end up winding the pulley string around the motor mount. If
we aren’t able to release the gadgets into the sorting area we won’t be able to score.

8
.0 Research Paper



Six
Sigma
is the measure of the number of defects that can be in a certain task or operations.
It is a business strategy and management philosophy that set high standards and expectations
by collecting data and analyzing results. The goal of six

sigma

is to get zero degree of error
tolerance so it can reduce waste, defects, and irregularities in products and services.
(howstuff.com)



In the mid 1980’s six sigma was created by a quality engineer named Bill Smith. Six


sigma
comes from the idea that

six standard deviations between the process average and the nearest
specification limit, then almost no items will fail to meet the processes specifications. It was
created to improve company’s quality, productivity, resources, order entry, technical supp
ort,
and customer satisfaction. Six sigma works by locating and eliminating causes of different errors
causing a decrease in the chance to get a defect. A defect is and output in a process that does
not meet specifications. (isixsigma.com)(Microsoft.com)



Six sigma uses 2 methodology’s to help create new products and process designs and to
help improve an existing business process. The two methodology’s six sigma uses are DMADV
AND DMAIC. DMADV stands for Define goals, Measure product capabilities, Ana
lyze the design
alternative design details, and Verify design. DMAIC stands for Define problem, Measure key
aspects of the current process, Analyze data, Improve current process, and Control future state
process. (Microsoft.com)(isixsigma.com)


People

who are experts in Six Sigma are called black belts and green belts. The courses for
certification are available at the Industrial Engineers and by the American Society for Quality.
The Six Sigma Academy says that a black belt can save a company about $23
0,000 a project and
could probably complete four to six projects a year.(businessballs.com)


An important part of Six Sigma is the Five Whys. The Five Whys of Six Sigma are an organized
way to solve problems in a company. This problem solving solution

was invented by Sakichi
Toyoda. The process of Six Sigma is just asking the question why. By continuously asking this
question the main cause of the problem will appear. The Five Whys doesn’t necessary mean
that the company should ask five whys and the pr
oblem is solved. The Five Whys means that
the company starts to solve their problems by coming up with proof of why this problem has
occurred. The benefits of the Five Whys are simplicity, effectiveness, comprehensions,
flexibility, engaging, and it

i
s ine
xpensive. (www.itsmsolutions.com)(isixsigma.com)


While researching Six Sigma we came to find out that it we could apply its applications to
marble sorter project in our Principles of Engineering course. The objective of the marble sort
is to transpor
t, scan, and sort marbles based upon their color. Since Six Sigma is designed to
scan for defeats; Six Sigma would have been good to design the marble sorter and the program
for the marble sorter. Without Six Sigma problems could occur in the design or th
e program and
it could not be told what it is unless it was started scratch. If the marble sorter was to be used
trying to sort marbles it would be a lot easier because it would tell you if it would have a defeat
in the design and the program.

Six Sigma co
uld also help with the marble sorter when it

i
s time to determine the value for the
marbles. Trying to determine the value for the marbles depended on the space between the
photocell and the light, but it is hard to determine how much space is needed betwe
en the light
and the photocell. Sometimes the environment was the problem with the values of the
marbles. Six Sigma would be a lot easier to determine the values of the marbles because it
would tell you if it has a defeat. Meeting deadline would not be a p
roblem anymore in fact
could even get done with it before the deadline.



While researching six sigma we found out that

it would be useful to apply applications to
one of our previous Engineering projects. This previous Engineering project was called the
Marble Sorter Project. The Marble Sorter Project is a project that allows Engineering students
to put use their problem
solving techniques and their creation skills. A Marble Sorter is a system
created for the principal of engineering class that is designed to separate different color
marbles from clear to black into three to four different bins. To build a marble sorter
Fi
shertecnicks pieces were needed for the overall design but a phototransistor, a light, and
switches added to the design.


There were a lot of problems encountered will using the marble sorter. These problems
included: trying to get marbles onto a plat
form, the marble bouncing off the base of the
marble sorter, marbles not reading correctly which caused marbles to go into other bins,
writing new programs, working with different designs, redesigning the marble sorter, marbles
getting stuck in the hopper
(funnel for marbles to go through), switches, and the
phototransistor’s readings. All of these problems could have been fixed using six sigma’s five
whys. If we would have came up with logical reasons why things were not working instead of
just changing th
ings hoping we changed the right things.


The first set of problems that the five whys could have fixed were trying to get the marbles
onto the platform, the marbles bouncing off the base, and the marbles getting stuck in the
hopper. If we would have a
sked the simple question why we would have found out that
because the building structure was a little off it caused the marbles to fall off the platform and
bounce off the base. The solution to this problem in turn would be to make the structure
sturdier.


The second sets of problems that the five whys could have fixed were the marbles going into
the wrong bins, the phototransistor, and the switches. If we would have asked why we would
have found out that because of the lighting in the room, it caused t
he phototransistor to read
the wrong light causing the marbles to go into the wrong bin. If we asked why again we would
have found out that because the wires of the switches kept coming out the interface box (a
device that is hooked up to the back end of t
he computer that allows wires to get plugged into
it allowing the user to create a program based on their designs) this cause the switches not to
work. The solution to these problems would be to cover up the area around the phototransistor
allowing little
light to penetrate and to tighten up the wires on the switches to work.

The last sets of problems that the five whys could have fixed were to write a totally new
program, a different design, and redesigning. If we asked why we would have found out that
bec
ause the marble sorter was someone else’s it caused the new people working on it to have
difficulties with the programming, and design causing them to redesign. The solution to these
problems would have been for the new people working on the marble sorter
to use there own
marble sorter or to ask the person’s who marble sorter they’re working on to help them with
its


programming and design. The five whys would have been an excellent tool to have with the
marble sorters because it showed that all the problem
s with the marble sorter were all linked
together.


The main problems were working with a new design and program. These problems
linked to the problems of the hopper, and the structure. These later lead to the problems
dealing with the phototransistor’s re
ading, the separation of marbles into the correct bins, and
the wiring or the switches. By Six Sigma’s Five whys helping this would allow the marble sorter
to be completed on time with hardly any mistakes.


Work Cited




howstuff.com



isixsigma.com



Microsoft.
com



http://www.itsmsolutions.com/newsletters/DITYvoliss39.htm



http://www.isixsigma.com/ library/content/c02061a.asp,page1



http://books.google.com/books=six+sigma.source



http://www.businessballs.com/sixsigma.htm



http;//office.microsoft.com/en
-
us/help/HA011233361033.aspx