Overview of the
Prosthetic Arm Challenge
2012-2013
MESA USA National
Engineering Design
Competition
Prosthetic Arm Challenge Introduction

A classmate has recently lost part of her arm
below the elbow. She now needs a prosthesis
that is low-cost and easily maintained that will
allow her to complete daily tasks in school and
at play.
What is a Prosthesis?
A prosthesis is an artificial limb (an
artificial substitute) that replaces a missing
leg or arm due to disease, accidents, or
congenital defects.
 Main types of artificial limbs:

◦
◦
◦
◦
Transtibial prosthesis
Transfemoral prosthesis
Transradial prosthesis (MESA Prosthetic Arm Challenge)
Transhumeral prosthesis
A U.S. soldier demonstrates
table football with two
transradial prosthetic limbs
i-limb ultra, by Touch
Bionics, has five
individually powered digits
and went on sale in 2007
for $17,454
The Jaipur foot, a transtibial
prosthesis, is readily available to
impoverished nations and costs
$35. In contrast, prosthetics in
the U.S. cost from $5,000 to
over $100,000.

Prostheses in the United States are made
from materials such as plastic, metal
(aluminum, steel, titanium), silicon, latex, and
carbon fiber. These devices can also have
robotics components.
Man builds himself bionic hands

Sun Jifa lost both his hands when a
homemade blast fishing bomb exploded
prematurely. Unable to afford the
prosthetic limbs offered by a hospital, he
created his own.
◦ Source: http://news.yahoo.com/photos/man-buildshimself-bionic-handsslideshow/#crsl=%252Fphotos%252Fman-buildshimself-bionic-hands-slideshow%252Fbionic-handsphoto-1345045308.html
“I survived, but I
had no hands,” he
explained.
After the accident, Sun Jifa, 51, of
Guanmashan, Jilin province in northern China
desperately needed to work on his family
farm, according to the Daily Mail.
Jifa spent eight
years handcrafting
prototypes before
finally creating
metal hands that
could grip and hold.
“I couldn’t afford to buy the false hand the
hospital wanted me to have, so I decided to
make my own,” Jifa says.
The devices depend
on a series of wires
and pulleys inside,
and are controlled
by movements in his
elbows.
“I made this from scrap metal for virtually
nothing,” Jifa says.
Jifa says he will
further develop the
design for other
disable people.
“There is no need to pay hospitals a fortune,”
Jifa says.
MESA Advisors and Challenge
MESA Advisor
Shows Off Her
Group’s Device
MESA Advisors from the USC Center utilize re-purposed
materials to build a prosthetic arm device to pick up a ball
and other objects.
Prosthetic Arm Challenge Overview
The MESA USA Prosthetic Arm Challenge
involves the development of a low-cost prosthetic
device to complete pre-defined tasks. The
challenge has four components: Performance,
Technical Paper, Academic Display and Oral
Presentation.
Objective:
Teams will build a low-cost prosthetic arm for use by a
classmate who recently lost part of her arm below the
elbow. The device should be designed to be low-cost and
easily maintained and allow her to complete daily tasks in
school and at play. The device must meet the criteria
outlined in the rules and be designed to perform the predefined tasks.

Device Performance – 150 points
◦ Distance Accuracy Relay
◦ Object Relocation
◦ Dexterity (high school only)
Device Efficiency – 50 points
 Technical Paper – 100 points
 Academic Display – 100 points
 Oral Presentation – 100 points

Challenge Performance Tasks
1.
2.
3.
Distance Accuracy Relay: greatest
distance and accuracy achieved by tossing
balls of different sizes into target containers
at different distances
Object Relocation Task: greatest massto-time ratio achieved by placing objects of
varying weights into a container
Dexterity Task: greatest number of bolts
and nuts correctly placed and secured onto
testing device
*Middle school devices will be judged on the first two tasks only.
General Rules


Device must attach halfway between elbow and wrist,
and extend beyond real hand.
Device must include hand mechanism (at least 2 fingers)
and must open and close w/o assistance from opposite
elbow, forearm or hand.
◦ Hand mechanism must open at least 10 cm.
◦ Objects in each task MUST be grasped, taken hold of, or grabbed
on part of device that extends beyond hand (i.e. the “fingers” of
device). Can NOT use any other part of device or parts of own
hand, wrist, or arm to grasp, take hold of, or grab objects.

Device, including all parts of all configurations, cannot
weigh more than 3 kg.
All parts and materials of the device cannot exceed $40
pre-tax price limit
 Must complete and submit provided itemized budget
sheet and attach receipts and/or online retail price
print-outs to support prices listed.
 Device cannot utilize team member’s wrist, hand, or
fingers in any way.
 Team will determine their method of immobilization
and must demonstrate this for judges.
 In addition, a latex glove will be placed over member’s
CLOSED FIST before attaching device.
 Parts may NOT be added, removed, replaced, or
readjusted during trial; between trials is allowed.

Distance Accuracy Relay Highlights

Target containers at three different distances
◦ Containers are Home Depot’s “Homer’s All-Purpose Buckets
 2 meters from launch line
 3.5 meters from launch line
 5 meters from launch line

Relay objects are three different size balls
 5 standard size tennis balls (≈ 2.5 inches)
 5 vinyl kick balls (2 inches)
 5 standard size ping pong balls (≈ 1.5 inches)

Relay objects
randomly placed in
cardboard box

Top lid of an Office Depot
Copy Paper 10 reams box
Diagram 2




1 minute to prepare and demonstrate device, and to
place device and box with Relay Objects anywhere on
table.
When given start order, first designated team member
enters Working Area, attaches device, and tosses as many
of the SAME TYPE of balls.
Teams MUST toss all types of same balls before tossing
subsequent types of same balls.
At least two team members MUST participate in the
relay. One member must not toss more than two types
of balls.
Only ONE of the balls may be grabbed at a time.
 Only balls inside designated box may be used for
tossing.
 Trial will conclude:

◦
◦
◦
◦
At end of 90 seconds
When a member grabs more than one ball
When a member tosses wrong type of ball
When any part of member’s body including arm and device
crosses launch line when tossing ball
◦ When target container is knocked over
Score Matrix
2m
Target
3.5m
Target
5m
Target
Tennis Ball
10
15
25
Kick Ball
15
20
30
Ping Pong Ball
25
30
40
Object Relocation Task Highlights


Objects
1.
Two – 20 ounce Dasani bottles of water
2.
Two – 1 liter Dasani bottles of water
3.
Two – 1 lb boxes of Crayola Modeling Clay
4.
Two – Master Lock 1500D 1 ⅞” Combination Locks
5.
Two – Quart size Ziploc bags with 200 Pennies
6.
Two – Spindle of 30 CD’s
7.
Two – 2 inch by 20 yard Rolls of Duct Tape
8.
Two – 4 oz. bottles of Elmer’s Glue All (white school glue)
9.
Two – Packages of 12 AA Energizer Batteries
10.
Two – Composition Notebooks, 100 pages, page size 7.5” L x 9.5” W
11.
Two – 1 lb Box of Grip-Rite Nails any size, box dimensions approximately 2” H x 4.75” W x 3.5” L
12.
Two – Packs of 100 3” x 5” Index Cards
13.
Two – Spiral Bound 3 Subject Notebooks, 120 pages, size 10.5” L x 8” W
14.
Two – Rolls of 1” x 60 yards masking tape
15.
Two – 1 pound bags of pony beads (approximately 2000 beads)
10 of the 15 item groups will be selected on day of
competition
1 minute to prepare, attach, and
50 cm
50 cm
76
demonstrate device, and to place
cm
83 cm
container in one “Container Area”.
Diagram 3
 At end of 1 minute or when device is prepared,
attached and ready, designated team member will stand
outside of Working Area.
 1 ½ minutes (90 seconds) to complete task.
 At least 5 different item types MUST be place in
container or trial will be declared a mistrial.
 Team may call end of trial before 1 ½ minutes have
passed by calling out “done”.
 Any item held by device when time is called will not be
counted towards total mass of container.

Dexterity Task Highlights
For high school teams ONLY
 Testing device made from two
1 foot x 6 inch x 1 inch boards
attached perpendicular to
Diagram 6
each other.
 Vertical board with three pre-drilled holes
FRONT VIEW

1’ Length
A
B
C
3”


3 inches from edge and 3 inches from top

Hole “A” = 6.9mm Metric Drill (US-17/64)

Hole “B” = 10.0mm Metric Drill (US-27/64)

Hole “C” = 14.2mm Metric Drill (US-35/64)
Dexterity Materials include:

Hole “A” = 8mm x 1.25mm hex bolt and nut, and 13 mm wrench

Hole “B” = 12mm x 1.5mm hex bolt and nut, and 19mm wrench

Hole “C” = 16mm x 2.0mm hex bolt and nut, and 24mm wrench
6” Height

1 minute to prepare, attach, and demonstrate device,
and to prepare “Testing Area” and dexterity materials.
◦ Testing Device can be placed in either Testing Area (50 cm square).
◦ Dexterity materials placed outside of Testing Area.



At end of 1 minute or when device is prepared,
attached and ready, designated team member will stand
outside of Working Area.
2 minutes to complete task.
Member may sit or stand and may move chair and/or
stand anywhere in Working Area.

Task is as follows:
◦ Grab and place hex bolt into corresponding pre-drilled holes.
 May hold head of hex bolt with non-prosthetic hand ONLY. May NOT twist
or screw in any way or trial will stop and be declared a mistrial.
◦ Grab corresponding hex nut and place onto bolt.
◦ Grab corresponding wrench and screw hex nut onto bolt.
◦ Repeat for all three hex bolt and nut sets.


May choose in what order each bolt/nut set is secured
but must place a nut on a bolt before attempting
another. Once all three nuts have been placed on bolts,
may re-visit any bolt/nut set to score more points.
Each hex bolt will have a marking every 0.5 cm from
base of bolt head.
Reminders
Safety first: Since transradial prosthesis will
be attached to student’s arm, please keep
safety in mind at all times.
 Stay within all the parameters of the project.
 Research, brainstorm, build, test, record, revise,
build, test, record, revise, build, test,…

◦ Use the Engineering Design Process

READ ALL THE RULES!!!
Activity 1 – Relocating Objects

Objective
◦ Design, build and operate a transradial prosthesis from given
supplies to grab various size objects one a time and release
them into a container

Supplies per group
◦
◦
◦
◦
◦
◦
2 sheets of card stock paper
5 feet of string
9 straws
14 craft sticks
3 beads
Activity Sheet
Activity 1 Instructions

Using the given supplies, design and build a transradial prosthesis. The prosthetic
arm should be attached half way between the elbow and wrist and should extend
beyond the real hand.
◦ Device MUST have hand mechanism and MUST open and close.
◦ Can NOT use opposite elbow, forearm or hand OR real hand to operate or
control the prosthetic arm.
Creating One Finger with Two Joints

Cut one craft stick into three equal pieces.

Cut two pieces of straw slightly shorter than the pieces of sticks.

Glue one piece of straw to one piece of stick. Put the glue on the stick and not the
straw or the straw may melt. Do this for a total of TWO straw/stick segments.

Glue the two stick segments onto a full straw. The sticks should be sandwiched
between the straws now. Leave a small space in between each segment, so that
bending is possible at the joint.

Glue full straw’s excess onto a full length craft stick. Leave a small space between
the full length craft stick and the first segment, so that bending is possible at the
joint.
Activity 1 Instructions continued

Glue one more straw segment onto the top of the full length craft stick in line with
the other two segments.

Tie a bead onto the end of piece of string. Use the bamboo skewer to thread the
other end of the string through the first short straw segment and through the two
other short straw segments.

Wrap each segment with tape to reinforce the glue. Pre-bend the finger at each
joint.
Creating Arm and Operation

Using the remaining supplies, create two more fingers, the arm and the operation of
the fingers.
Testing

Attach the transradial prosthesis and pick up the different objects from a table one
at a time and release them into the container/box.
Activity 2 – Tossing Balls into Targets

Objective
◦ Design, build and operate a transradial prosthesis from any of
given supplies to toss various balls one a time into cups at
different distances.

Supplies per group
o
o
o
o
o
o
o
5 – sheets of 9” x 12”
construction paper
3 feet of masking tape
5 index cards
1 pair of scissors
2 plastic spoons
3 feet of string
5 straws
o
o
o
o
o
o
10 craft sticks
5 – 3 ½” rubber bands
10 small paper clips
10 large paper clips
10 fasteners
Activity Sheet
Activity 2 Instructions
1.
Using any of the given supplies, design and build a
transradial prosthesis. The prosthetic arm should be
attached half way between the elbow and wrist and
should extend beyond the real hand.


2.
3.
4.
Device MUST have hand mechanism and MUST open and close.
Can NOT use opposite elbow, forearm or hand OR real hand to
operate or control prosthetic arm.
Place cups 1 foot, 2 feet, and 3 feet from launch line. No
part of team member or device may cross launch line.
Arrange different balls from smallest to largest.
Attach transradial prosthesis and grab and toss one ball
at a time; toss same type of ball before tossing
subsequent type of same ball.
Questions?
Ben Louie
USC MESA
blouie@usc.edu