01 PriMA_DetailDesignReport

PRIMA
DETAILED DESIGN REPORT
BIOMEDICAL ENGINEERING DESIGN 1 & 2: BME 4292 & 4293
FALL 2015 - SPRING 2016
FLORIDA INSTITUTE OF TECHNOLOGY
TEAM MEMBERS:
CLYDE (DOUG) BROWN - TEAM LEADER
THADDEUS BERGER - FINANCIAL LEADER
TAYLOR ATKINSON
RYAN BABBITT
NICOLE BALLMAN
MEET PASTAKIA
JUSTIN PAVAO
AUSTIN SPAGNOLO
ZUHOOR YAMANI
MARIA VITTORIA ELENA
DANNIELLE GOLDMAN
PROJECT ADVISORS:
DR. KUNAL MITRA
MR. DAVID BEAVERS

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EXECUTIVE SUMMARY
A low-cost, highly functional prosthetic armdesign has been developed by the PriMA senior design team at Florida
Institute of Technology. The group has found a way to provide a novel medical device which could become a
competitive product on the market. The device is strong, lightweight, and non-invasive, and has a wide array of
sensory capabilities and a novel system for tactilefeedback which can be used to drivethe hand.
ACKNOWLEDGEMENTS
PriMAwould liketo thank all advisorsand supporters to this project.Special thanksto our advisors,Jennifer Schlegel,
the Kern Entrepreneurial Engineering Network, and Tabitha Beavers and ProjectBased Learning.
CONTENTS
Executive Summary .........................................................................................................................................................................1
Acknowledgements .........................................................................................................................................................................1
Figures................................................................................................................................................................................................3
Tables.................................................................................................................................................................................................5
1: Introduction..................................................................................................................................................................................6
1.1: Problem being addressed...................................................................................................................................................6
1.2: Motivation.............................................................................................................................................................................6
1.3: Global, social, economic, and contemporary impact....................................................................................................6
1.4: Final problem statement ....................................................................................................................................................6
2: Background...................................................................................................................................................................................7
2.1: Literature Review.................................................................................................................................................................7
2.2: Patent Search .......................................................................................................................................................................7
2.3: Research Required to Design and Build Prototype......................................................................................................12
2.4: Current State of the Art ....................................................................................................................................................15
2.5: Regulatory and Economic Constraints...........................................................................................................................20
2.6: Ethical, Safety, and Liability Issues .................................................................................................................................20
2.7: Client Survey Synopsis ......................................................................................................................................................21
3: Preliminary Designs...................................................................................................................................................................22
3.1: Appearance/modularity...................................................................................................................................................22
3.2: Determine Platform..........................................................................................................................................................22
3.3: Motors .................................................................................................................................................................................23
3.3.1: Wrist Motor ................................................................................................................................................................23
3.3.2: Thumb Motors ...........................................................................................................................................................23

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3.3.3: Finger Motors .............................................................................................................................................................23
3.4: Electronics...........................................................................................................................................................................24
3.4.1: Sensors.........................................................................................................................................................................24
3.4.2: Myoelectric.................................................................................................................................................................24
3.4.3: Batteries ......................................................................................................................................................................25
3.4.4: Processing Board.......................................................................................................................................................26
3.4.5: Arduino Motor Shield V2 microcontroller.............................................................................................................26
3.6: Structure..............................................................................................................................................................................27
3.6.1: Fingers .........................................................................................................................................................................27
3.6.2: Palm.............................................................................................................................................................................27
3.6.3: Thumb..........................................................................................................................................................................28
3.6.4: Wrist.............................................................................................................................................................................28
3.6.5: Forearm.......................................................................................................................................................................28
3.6.6: Neoprene Connection Sleeve ..................................................................................................................................29
3.7: Materials .............................................................................................................................................................................30
3.7.1: Polymer Selection......................................................................................................................................................30
3.7.2: Dampening..................................................................................................................................................................30
3.8: Size Restrictions ................................................................................................................................................................30
3.9: Human Factors ...................................................................................................................................................................31
3.9.1: Health & Safety ..........................................................................................................................................................31
3.9.2: 3D scanning and mold impressions........................................................................................................................31
3.9.3: Blood circulation........................................................................................................................................................31
3.10: Failure Factors..................................................................................................................................................................33
3.11: Manufacturing .................................................................................................................................................................34
3.11.1: Methods: 3D Printing vs. Casting..........................................................................................................................34
3.12: Analysis of Functionality.................................................................................................................................................35
3.12.1: Stress analysis ..........................................................................................................................................................35
3.12.2: Thermal Analysis......................................................................................................................................................35
3.12.3: Watertight and Corrosion Resistant System ......................................................................................................36
4: Final Design.................................................................................................................................................................................36
4.1: Final Solution Principles....................................................................................................................................................36
4.2: Functional Analysis............................................................................................................................................................36
4.3: Parameters and Constraints ............................................................................................................................................36

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4.4: Design Analysis...................................................................................................................................................................38
4.4.1: Linkage.........................................................................................................................................................................38
4.4.2: Palm/Knuckles............................................................................................................................................................39
4.4.3: Fingers .........................................................................................................................................................................39
4.4.4: Forearm.......................................................................................................................................................................40
4.4.5: Thumb..........................................................................................................................................................................40
4.5: Decision Analysis................................................................................................................................................................40
4.6: Quality Function Deployment (QFD) ..............................................................................................................................42
5: Prototype Development and Testing.....................................................................................................................................43
5.1: Bill of Materials (BOM) and Rationale for Use .............................................................................................................43
5.2: Prototype Fabrication Process ........................................................................................................................................44
5.3: Assembly .............................................................................................................................................................................45
5.4: Prototype Testing Protocol..............................................................................................................................................46
5.5: Tests Performed and Results...........................................................................................................................................47
6: Conclusions and Future Work.................................................................................................................................................48
6.1: Implications of Results......................................................................................................................................................48
6.2: Future Work and Improvements ....................................................................................................................................48
6.3: Errors....................................................................................................................................................................................48
6.4: Final Evaluation of Design................................................................................................................................................48
7: References ..................................................................................................................................................................................49
FIGURES
Figure 1: Patent No US 5443525; perspective view showing a prosthesis liner equipped with the novel pad..............8
Figure 2: Patent No US 6589287;shows an embodiment of the invention into a prosthesis or hand with l osttactile
sensation...........................................................................................................................................................................................9
Figure 3: Patent No US 20090048539;shows a partial cutaway viewof a section of a phalangeal portion associated
with a distal end of one of the digits of prosthetic hand device...........................................................................................10
Figure 4: Patent No US 20090048539;illustrates oneembodiment of the system, wherein sensors (2) areapplied to
a hand prosthesis or a hand without sensation or a glove (1) and are connected to a processor (3) via electrical or
hydraulic conduits(7a),said processor (3) beingconnected by electrical or hydraulic conduits (7b) to signal
transducers (4),arranged on the forearm, forming a tactile display (5).............................................................................10
Figure 5: Patent No US 20090048539;shows sideviews of the prosthetic hand device in various positions,
illustrating one configuration for parallel elastic elements in accordance with an embodiment of the invention. ...10

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Figure 6: Patent No US 20090048539;an anterior view of a prosthetic hand device in accordancewith an
embodiment of the invention. ....................................................................................................................................................11
Figure 7: Patent No US 20130046394;simplified illustration of an embodiment of a myoelectric prosthesis control
system..............................................................................................................................................................................................12
Figure 8: The iLimb Hand by Touch Bionics (Competitor 2)...................................................................................................18
Figure 9: The Vincent Hand by Vincent Systems (Competitor 1). .........................................................................................18
Figure 10: The iLimb Pulse by Touch Bionics (Competitor 3).................................................................................................18
Figure 11: The Bebionic Hand by RSL Steeper (Competitor 4). .............................................................................................18
Figure 12: The Michelangelo hand by Otto Bock (Competitor 6). .......................................................................................18
Figure 13: The Bebionic Hand v2 by RSL Steeper (Competitor 5).........................................................................................18
Figure 14: Images of Fingers and Kinematic model jointcouplingmechanismof fingers studied.(1) Vincent hand,
(2) iLimb and iLimb Pulse,(3) Bebionic and Bebionic v2, and (4) Michelangelo.Here, θ1 is the angleof metacarpal
phalange joint and θ2 is the angle of proximal interphalange joint.....................................................................................19
Figure 15: (1) The Central Drive Mechanismof Michelangelo hand,(2) Placement of motor in Proximal Phalange,
rotatingworm againstfixed gear in Vincent hand, and (3) iLimb finger actuated in the samemanner as Vincent
hand, but uses bevel gears between worm drive and motor. MCP = Metacarpal Phalange...........................................19
Figure 16: Tamiya DC motor parallel axis gearbox..................................................................................................................23
Figure 17: Lead screw N20 brushless DC motor.......................................................................................................................23
Figure 18: Force-sensitive resistor..............................................................................................................................................24
Figure 19: Myoelectric sensor kit................................................................................................................................................24
Figure 20: Temperature resistor.................................................................................................................................................24
Figure 21: Tenergy NiMH battery cell........................................................................................................................................25
Figure 22: Arduino Uno circuitboard..........................................................................................................................................26
Figure 23: Stackable Arduino V2 Motor Sheild.........................................................................................................................26
Figure 24: Open hand gesture. ....................................................................................................................................................27
Figure 25: Closed hand gesture...................................................................................................................................................27
Figure 26: Palm and knuckles separated. ..................................................................................................................................27
Figure 27: Palm and knuckles connected. .................................................................................................................................27
Figure 28: Wrist connection.........................................................................................................................................................29
Figure 29: Forearm and wrist assembly.....................................................................................................................................29
Figure 30: Schematic of electrical components to be built into the sleeve. .......................................................................30
Figure 31: Neoprene sleeve with PriMA logo...........................................................................................................................30
Figure 32: Basic below-elbow disarticulation amputation and human anatomy. .............................................................32
Figure 33: Synthetic lab testingarm with artificial muscles, veins, and nerves.................................................................32
Figure 34: Dual-axis extrusion 3D printer..................................................................................................................................34

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Figure 35: Layer ridges and separation......................................................................................................................................34
Figure 36: Finger assembly simulation.......................................................................................................................................35
Figure 37: Knucklesimulation. ....................................................................................................................................................35
Figure 38: Linkage bar simulation...............................................................................................................................................35
Figure 39: Slider jointsimulation................................................................................................................................................35
Figure 40: Schematic of four bar linkage driving fingers........................................................................................................38
Figure 41: Palm and knuckles......................................................................................................................................................39
Figure 42: Fingers...........................................................................................................................................................................39
Figure 43: Forearm attached to hand. .......................................................................................................................................40
Figure 44: QFD spreadsheet.........................................................................................................................................................42
Figure 45: Full newest version arm assembly with sleeve connection. ...............................................................................45
Figure 46: Sleeve connection subassembly...............................................................................................................................45
Figure 48: Subassemblies of the hand, finger, and forearm..................................................................................................46
Figure 47: Test conducted of motors driven by EMG signals. ...............................................................................................47
TABLES
Table 1: General properties of prosthetic arms currently available in the market. ..........................................................16
Table 2: Grip and kinematic characteristics of prosthetic arms currently availablein the market. ...............................17
Table 3: Daily Battery Power Consumption ..............................................................................................................................25
Table 4: Failure Factors.................................................................................................................................................................33
Table 5: Blood flowstimulation decision chart........................................................................................................................41
Table 6: Arm connection decision chart....................................................................................................................................41
Table 7: Battery decision chart....................................................................................................................................................42
Table 8: Bill of Materials...............................................................................................................................................................43

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1: INTRODUCTION
1.1: PROBLEM BEING ADDRESSED
Prosthetic arms havebeen in existencesincethe antiquity,with the technology evolvingfrom rudimentary materials
to the current field of robotics.Whileprostheses arevital in enablingamputees to lead somewhat normal lives,they
are responsible for causing acute pain to their users due to bad fit and complex features. Existing prostheses are
cumbersome, hence causing painful blisters or sores that add to the discomfort of amputees (Schweitzer).
Furthermore, the manufacturers make standardized prostheses that do not accountfor the different dimensions or
location of the nubs, makingdiscomfortthe primary causeof the stoppage in the use of prostheses.
1.2: MOTIVATION
The motivation for addressingthe discomfortproblem stems from numerous complaints fromcustomers regarding
bad fit, heaviness, and exorbitant prices of prostheses. The crux of the issue is the failure of manufacturers to
customize prostheses to the requirements of every individual. Furthermore, manufacturers add extra features on
the devices as a ploy to charge inflated prices.Some prostheses cost as high as $100,000,making it impossiblefor
most amputees to afford (CostHelper Health). The introduction of low-cost prosthetic arms in the market will,
therefore, meet the existingdemand.
1.3: GLOBAL, SOCIAL, ECONOMIC, AND CONTEMPORARY IMPACT
Today, the global arena is riddled with warfare, terrorism and arterial diseases that increase the incidence of
amputations. The prevalence of arterial diseases thatimpede proper blood circulation in the limbs arethe leading
causes of amputation,followed by conflicts involvingtheuseof guns and explosives (DisabledWorld.com).Therising
cases of amputees indicate the possible victims of pain caused by poorly designed prostheses. The result will be a
massive decline in the popularity and use of the devices in the market. On a social level, the pain arising from the
bulkiness of prosthetic arms increasethephysical and mental distress of amputees,thus negatingthe goal of medical
care. Thus, acute depression is likely to result, leading to the loss of the productive capacity of the victims, while
increasing their dependency level. On an economic level, the manufacture of prosthetic arms acts as a source of
revenue for manufacturers and paves the way for innovation and employment. However, the exorbitant prices
charged on the devices, coupled with costly repairs and stringent warranty restrictions will reducetheir popularity
in the market (Schweitzer). The result will be fewer profits and tax revenue for both the manufacturers and the
government respectively. Lastly, contemporary societies want not only high-tech prostheses but also devices that
resemble actual limbs.Thus,the cosmetic trend of arm prosthetics is likely to persistin the years to come.
1.4: FINAL PROBLEM STATEMENT
Comfort must be a priority for all manufacturers if prosthetics are to survive in the market. Therefore, this paper
focuses on how to create an inexpensive technologically-advanced prosthetic arm that is both lightweight and
comfortable.

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2: BACKGROUND
2.1: LITERATURE REVI EW
Preliminary study on theproducts currently availablein themarket indicated thatthe weight of the prosthesis isone
of the crucial deciding factors that determines if the amputee would use the prosthesis or not. Even though the
prosthesis may weigh the same as the actual arm of the patient, it acts as an additional objectthat is perceived by
the amputee as heavy because itdoes not naturally belongto the body. Another important factor of the prosthesis
is its size.It plays a vital rolein how comfortable and accurateprosthesis is by determining its maneuverability and
easeof use.Italso determines how comfortableand accuratetheprosthesis isfor usein daily activities.Other factors
that are important in the prosthesis design to determine how closely it mimics the functions of an actual arm are
number of joints,degrees of freedom, range, accuracy of forceapplied,actuation method and number of actuators.
Research on previously made prostheses indicated that grasp type, range of motion, and grip force are additional
factors that determine the maneuverability and smoothness function of the prosthesis that replaces the lost arm.
The range of forces that the prosthesis can apply determines the amputee’s ability to hold and lift either heavy or
the fragileobjects,which in turn is dependent on the grip force. Hence, a prosthesis thatcan apply a wide range of
grip forces is optimal for graspinga variety of objects. It is good for the prosthesis to apply as much minimum value
of force as possibleto hold a fragileobject. In a similar manner,itis better for the prosthesis to apply as much high
valueof force as possibleto hold a heavy object. The range of motion is also an importanta spectfor the prosthesis
to mimic an anatomical armas itaffects theflexibility and accuracy.Overall,thecloser thesefactors areto the actual
arm, the better the prosthesis will serve its purpose. Some other important factors that make the prosthetic arm
similar to anatomical armarethe robustness,battery life,cosmesis,and sensory feedback of the prosthetic arm.
Another factor that needs to be taken care of while designing the prosthesis is its weight. An average human arm
weighs about 440 g when the forearm extrinsic muscles are excluded. Studies conducted in the past have shown
that prosthesis which are designed to be around 440 g are perceived by the patients as heavy as it is supported by
the soft tissue on the residual arm and is not directly connected to the skeleton itself. In addition, more weight is
put on a small area if the residual armis small and hence heavier the prosthesis is perceived if attached to it. So, a
significantincrease in the perceived weight of the prosthesis is observed with decrease in the sizeof residual arm.
Hence, if the weight is large,theprosthesis can contributeto fatigueand discomfort,and if itis small,itcan beuseful
as a replacement arm without causing these problems. Online surveys previously conducted on prosthesis users
showed that approximately 80% of the users perceive prosthesis to be too heavy. The users rated weight as 70 on
the scaleof 0 to 100 in terms of factors that areimportant for comfort.
2.2: PATENT SEARCH
To further obtain the information regarding prosthetic arms and such devices in the market, five patents were
studied to determine the options currently available.All the products studied were different designs of mechanics
in the prosthesis, sensory feedback devices for tactile information about objects that are being touched by the
prosthesis and myoelectric prosthesis control. These patents were studied because each device included design
elements that can be incorporated in the new myoelectric prosthetic arm design. Each of the sections below will
separately discussaboutthe description of the patent and about how the patents apply to the design.

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US 5443525: CONDUCTIVE PATCH FOR CONTROL OF PROSTHETIC LIMBS
This patentspecifies a novel pad thatincludes an electrically conductivegrid includinga very largeplurality of densely
packed electrical contacts embedded within a non-conductive siliconerubber matrix.The patent’s descriptions are
written generally to encompass full contact of the electrodes to the amputee’s ski n at all time and to allow the
detection of multitude of myoelectric signalsmoreaccurately.
The general geometry of this novel pad is described as including an
electrically conductive grid that includes very large plurality of densely
packed electrical contacts embedded within a nonconductive silicone
rubber matrix. The unique device can be provided in any desired size and
itcan preferably be bonded to the interior surfaceof the socketor liner for
direct, conforming, non-migrating contact with the user’s skin. Since the
resistivity of this device is very small, less than 0.001 Ω cm, it can detect
even a small change in the myoelectric current. Each contact within the
grid has a size of about 0.002 inches square and the contacts are spaced
about 0.005 inches apart, measured between centers. Thus, a 1-inch
squaregrid contains aboutforty thousand discretecontacts.
A multitude of myoelectric impulses can be measured through this device
since it allows several pads to be placed at specific locations on the
amputee’s body. Due to the ability to easily conform the pads to the
amputee’s skin and because of the high density of conductors on the pad,
the accuracy of the myoelectric signals, its reliability of detection, and its reproducibility is increased significantly.
This allows for the development of a control system capable of producing a very complete range of motions in a
prosthetic hand or other prosthetic device by helping the control system sort through and organize the complex
myoelectric signals. Hence, this patented device can provide a breakthrough in myoelectric control system by
eschewing the large, metallic electrodes currently in use with several tiny electrodes that can be placed in
comfortable, non-migratingrelation to the patient’s skin.
STRENGTHS:
The main advantage presented in this patent is the ability to detect even a small change in myoelectric signal
accurately and reproducibly.Not only can it be used for different patients reliably withoutmakingany changes, the
electrode pad can be calibrated to perform atdifferent myoelectric signalsfor differentpatients usingthis device.
WEAKNESSES:
Acquisition of myoelectric signals may still cause the electrodes to slip away from its original position due to
sweating. The signal acquisition and processing system should be able to work with a huge amount of data coming
from several electrodes which may make the prosthesis too costly (due to high processingpower),or laggingdue to
significanttimeconsumed in the processingof myoelectric signals.
Figure 1: Patent No US 5443525; perspective view
showing aprosthesisliner equipped with the
novel pad.

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US 6589287: ARTIFICIAL SENSIBILITY
This patent for artificial sensibility of objects touched by the prosthesis when it is
use. It consists of sensors applied to the left finger of the, middle finger, and right
finger of the prosthesis. These sensors are connected to a headphone unit
consistingof leftand rightspeaker, via a signal amplifier.Whenever a finger comes
into contact with a surface, the sensor sends a signal to an amplifier which then
repeats a stronger signal to theleft speaker of the headphone. This notifies theuser
that the left finger has moved. The process is identical for the right finger. For the
middlefinger, signal isheard fromboth the left and right speakers equally.
STRENGTHS:
The main advantage is providing the patient with the ability to sense the objects
touched by them with their prosthetic.Also,it has been shown that listeningto the
sound from different surfaces is morestimulating, and hence a better option, than
just seeing the prosthesis touch a surface. It helps the patient recover faster from
inability to detect when the prosthesis is touching a surface and what type of
surfaceis ittouching
WEAKNESSES:
A weakness of this method is that the touch feedback in the form of sound is not
natural.Ittakes sometime for the patientto learn various cues in theformof sound
while touching different objects with different textures. Also, placement of headphone distracts and impairs the
ability of patientto react to the natural sounds likesomeone callinghis/her name,or listeningto someone speaking
etc.
Figure 2: Patent No US 6589287;
showsan embodiment ofthe
invention into aprosthesisor hand
with lost tactile sensation.

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US 20090048539: SYSTEM AND METHOD FOR CONSCIOUS SENSORY FEEDBACK
The system and method for conscious sensory feedback is relevantto the design of prosthetic arm as itwould
providetactilefeedback. In this patent, the piezo-resistivemembranes as sensors arefixed to the volar partof the
fingers.These sensors produceelectric signalswhen induced by pressure.The signal produced by the sensors are
processed and transported to a tactiledisplay madeout of vibratingmotors actingas signal transducers.They are
placed parallel butclearly separated on the volar aspectof the forearm in a transversefashion fromthe medial to
the lateral side.Whenever one or several fingers of the prosthesis is touched,itinduces a vibro-tactilestimulus to
the skin of the forearm. The patient can easily learn and discriminatebetween individual fingers and different
touches without the use of vision.
STRENGTHS:
The main advantage in this patent is providingthepatient with the ability to sense the objects touched by them via
their prosthesis.Sincethe feedback is tactile,the patients can easily learn to differentiate various touch stimuli
without much difficulties.Also,unlikethe auditory feedback mentioned above, it does not impair the patient’s
ability to receive other forms of senses likesound.
illustratesone embodiment ofthe system,
wherein sensors(2)are applied to ahand
prosthesisor ahand without sensation or
a glove (1)and are connected to a
processor (3)viaelectrical or hydraulic
conduits(7a), said processor (3)being
connected by electrical or hydraulic
conduits(7b)to signal transducers(4),
arranged on the forearm, forming atactile
display (5).
Figure 5: Patent No US 20090048539; showsside
viewsofthe prosthetic hand device in various
positions, illustrating one configurationfor parallel
showsa partial cutaway view ofa
section ofaphalangeal portion
associated with adistal end ofone of
the digitsofprosthetic hand device.

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WEAKNESSES
The only weakness is that the patient has to learn to decipher various
types of vibrations for varioustypes of touches. Also, it would be better to
send sensory feedback directly to the nerve for natural response, but itis
a quite difficultand invasivemethod.
US 20120150322: JOINTED MECHANICAL DEVICES
In this patent a prosthetic device includes at least one member and hand
device coupled to the member. The hand device comprises of a base and
atleastone digitpivotably coupled to the base.Here the digitis comprised
of phalangeal portions connected by flexible joint portions. There is at
leastone actuatingstructure with its firstend coupled to the distal end of
the digit, where there is an actuatingstructure comprisingof at leastone
elastic element in series with at least one non-elastic element. The device
also includes at least one force actuator configured to apply force to a
second end of the actuating structure and a control system for adjusting
the operation of the force actuator based on at leastone actuation input,
an amount of given force, and an amount of displacement generated by
the force. The prosthetic device also comprises of electromyogram (EMG)
sensors for generating control signalsfromthe residual limb of the user.
The prosthesis further comprises of a computing device that can detect if certain part of the prosthesis is in contact
with an object and can operate force actuators, using the motion control mode and force control mode, based on
the amount of force and displacement. The device consists of at leastone restorativeel ement which applies force
oppositeto the actuator force.
STRENGTHS:
The main advantageis thatthe prosthetic hand can detect a variety of signalsand usethem to operate the actuators
like muscles in a real hand. The patient wearing this prosthesis can detect when the prosthesis is contact with an
object and can operate the actuators accordingly.This is done directly by a processor using the feedback obtained
from the sensors in the hand. Compliance characteristics of the device are automatically calibra ted by having the
hand slowly closeand open without graspingan objectwhilethemotor currentand position aremonitored to create
a position/forcemap in the absenceof an object.
WEAKNESSES:
The only weakness is thatalthough the prosthesis can detect its position and contactwith an object,itdoes not send
tactile feedback to the patient directly. In fact, the feedback is taken by the processor and necessary changes in
actuation aremade directly by the processor.Also,becauseof several sensors in the hand the processor drivingthe
prosthesis should bepowerful enough to perform several computations and real timechanges based on the position
of the prosthesis.This could also reducethe battery lifebecausemany computations require the processor to draw
more power from the battery.
Figure 6: Patent No US 20090048539; an anteriorview
of aprosthetic hand device in accordance with an
embodiment ofthe invention.

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US 20130046394: SYSTEMS AND METHODS OF MYOELECTRIC PROSTHESI S
The idea behind this patent is to provide a myoelectric prosthesis control system
that includes a gel liner that has layers and a plurality of leads at least partially
positioned between layers. The leads can be partially positioned between the
layers and coupled to electrodes. Moreover, the electrodes can include an
electrode pole that may be configured to contact the residual limb via the gel
liner.The electrode poles can be configured to detect electromyographic signals
and at least some of the electrodes and at least some of the leads can be
manufactured from a compliantconductivematerial.
A gel liner,for usewith myoelectric prosthesis control systems,is assembled from
a non-conductive fabric and electrodes. Leads are positions between the
electrodes and a thermoplastic elastomer beneath the gel. The layer of
thermoplastic elastomer can also be coated over the outer layer so that at least
one electrode will partially protrudefrom the layer of thermoplastic elastomer.
STRENGTHS:
The main strength of this patent is that the there areseveral electrodes that can
measure small changes in the myoelectric signal. Due to the involvement of the
several electrodes, the reception of false signals are significantly reduced,
providingmoreaccuratecontrol over the actuators operatingtheprosthesis.Each
electrode can includea pole that may be configured to contact the residual limb
when the gel liner is worn. The electrode poles can be configured to detect
electromyographic signals. Some of the electrodes and leads can be
manufactured from a compliantconductivematerial.
WEAKNESSES:
One of the weaknesses of this patent is thatthe placement of electrodes and leads is very complex.This could affect
the reparability of the system by compounding small problems.The complexity of the design can increasethe cost
of manufacturingcompared to other, simpler designs.
2.3: RESEARCH REQUIRED TO DESIGN AND BUI LD PROTOTYPE
Six types of prosthetic arms were benchmarked against each other to establish the baseline for the performance
required to design a new prosthetic arm.All of these prostheses were assessed in 12 categories:weight,size,number
of joints, degrees of freedom, number of actuators, actuation method, adaptive grip, grip force, range of motion,
grasp type and motor specification. The data for these categories were obtained through prior publications
comparing and discussing the development in upper arm prosthesis. The various prosthesis models seen in this
benchmarkingprocedure arein the Figures 2.3.1 to 2.3.6.
Each of these prostheses was evaluated usingthe12 criteria mentioned before by studyingvarious published articles
and studies carried out by a number of other groups on these prostheses. While the product specifications listed
here provide quantitative information about each product in comparison to the other, the qualitative information
of customer requirements and reviews is also mentioned in this document; Therefore, this document will provide
simplified illustrationofan embodiment
of amyoelectric prosthesiscontrol
system.

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both the relative quantitative information about the 6 products studied and the qualitative requirements of the
people sufferingfrom trans-radial amputation.
The qualitative criteria studied initially between the 6 products are presented in the Table 2.3.1. Here, the table
shows the weight of prosthesis which is an importantfactor as it is the added weight that the amputee has to carry
on the amputated arm, overall sizeof the prosthesis which determines its maneuverability and easeof use, number
of joints and degrees of freedoms which shows how closely theprosthesis can mimic thefunctions of an actual arm,
number of actuators, actuation method, joint coupling method and finally the function of adaptive grip which
determines the range and accuracy of forceapplied by the prosthesis whilegrabbingtheobjects.
The Table 2.3.2 below shows published kinematic and grip characteristicsof the prosthetic arms studied. The three
major categories: the grip force, range of motion and grasp type determines how maneuverable the prosthesis
would be, and how smoothly it would function as a replacement for the actual arm.The grip force determines the
range of forces the prosthesis can apply,which further determines the amputee’s ability to hold and liftboth heavy
and fragile objects. Prostheses with wider range of grip force are better at grasping a variety of objects, and the
prostheses with lower minimum values of grasp force are better at holding fragile objects. Range of motion
determines the flexibility and accuracy with which the amputation can function. Prosthes es with these values closer
to actual armservetheir purpose better than those who don’t.
The weights of prosthetic arms mentioned above are the weights of the entire system that the amputees need to
carry whileusingtheprosthesis.In caseof theiLimb Pulseand Bebionic v2 handsthetotal weightincluded controller,
battery, force sensing resistors and the distal side of the Otto Bock Electronic quick-disconnect unit. In case of the
Michelangelo, the total weight included the hand with protective sleeve, an Axon rotation wrist adapter, a large
battery, and controller. For the Vincent prosthesis, the same base can be used to attach fingers of three different
sizes (distal portions),each weighingfrom 2-4 g.
For the actuation method it was observed that five of the six prostheses tested had a proximal jointand singledistal
joint.The proximal jointwas similarto the human metacarpal phalange(MCP) and the distal jointwas similar to the
proximal interphalange(PIP) and distal interphalangecombined (DIP). Whereas the iLimb and Bebionic prostheses
had distal finger segment that gave look of a functional DIP, the Michelangelo hand consisted of single finger
segment with no joints, actuated only at a single point like the human MCP joint. In case of the i Limb, Vincent,
Bebionic, and Bebionic v2 the finger joints are not actuated independently, but have fixed relative movement to
each other. Each of these prostheses havetheir own unique method of couplingMCP and PIP joints usinga four -bar
linkage.Since,the spaceinsidetheprostheses is small,each of themodels used in this study contained motors which
incorporate high gear reductions. The motors were either placed in the proximal phalanx (iLimb, iLimb Pulse, and
Vincent hand usingMaxon DC Series 10 motors) or in thepalm(Bebionic,Bebionic v2,and Michelangelo usingMaxon
GP 10A motors). The Bebionic and Bebionic v2 hands use a custom linear drive developed by Reliance Precision
Mechatronics (Huddersfield, UK). Michelangelo uses a unique system with one large custom modified brushless
Maxon EC45 motor placed at the center of the palmto control flexion/extension of all the fingers at the same time
and a separatemotor in proximal region for abduction/adduction of the thumb.
The grasp forcewas measured on these prostheses usingpinch meters for precision graspsand a grip dynamometer
for lateral grasp and power grasps.For the grip force, the Vincent and iLimb Pulseuse an additional pulse mode to
increasethe holdingforce for individual finger significantly.After a set period of motor stalls,the motor is supplied
with quick pulses of power which basically ratchets the system to a higher capableholding force than what can be
achieved without the pulse mode system. An average of 69.5% increase and 91.5% increase in holding force of

14
individual finger was observed for Vincent hand and iLimb Pulsehand respectively becauseof the addition of pulse
mode. The drawback of this system is that it significantly reduces the battery li feof those arms. There was a lot of
variety in the designs and positions of thumbs in the prostheses tested. Thumbs have actuated MCP and PIP, and
circumduction jointthatcan be manually positioned in multiplestates in iLimb, iLimb Pulse,Bebionic,and Bebionic
v2. The Michelangelo hand prepositionsthethumb jointby a small motor prior to performinggrasps.Whilethemain
motor actuates to closethe hand (palmer or lateral grasp), the small motor changes the path that the thumb takes.
In addition,the thumb also has a natural-lookingrestingposition.
QUALITATIVE BENCHMARKING OF THE PROSTHETIC ARMS
Weight of the prosthesis is an importantfactor.An average human hand weighs about 440 g excluding the forearm
extrinsic muscles,butithas also been observed that the prostheses of similarweightaredescribed by the amputees
as heavy. Since these prostheses are supported by the soft tissueinstead of the skeleton on the amputee’s stump,
the weight perceived by them is increased significantly. Hence, the weight of the prosthesis is one of the major
factors contributingto the fatigue and discomfortrelated to its use.An onlinesurvey of myoelectric prosthesis users
has recently revealed that 79%of the patients consider their prosthesisto betoo heavy. Als o,the users rated weight
as 70 on the scaleof important factors (from 0 to 100) to be taken careof to make the prosthesis comfortable.Not
only the total weight, but the distribution of whatever weight the prosthesis hasisalso an importantfactor in making
the prosthesis feel comfortable.Prosthesis with heavier components likeactuators and batteries placed proximal to
the patientaremore comfortablethan those which havethe heavier components placed distal to thepatient’s body.
A range of 350-615 g is observed in the commercially available prostheses. These numbers are quite close to the
weight of an actual human arm, but still perceived heavier by the patients who use those prostheses.It is better to
have a prosthetic hand which weighs less than 400 g. Size is also an important factor for prosthetic arms. It should
look almostthe same as the actual armof an adultand henceshould havelength between 180-198 mm, and a width
between 75-90 mm, includingthecosmetic glove.
Finger kinematics which is anatomically correctis an importantfactor in mechanical design of the prosthetic hands.
Itis vital to keep a balancebetween the anatomical correctness,robustness,weight,complexity and cost.To do this,
a number of joints arecoupled to act as a singlecompound motion when powered by a singleactuator.The position
of actuator can be used to determine the position of all joints coupled together. A distinct set of movements that
can be described by a singleparameter is considered a singleDOF.Adaptiveunderactuation is also used for coupling
joints.Here, a singleactuator controls a number of independent DOFs.Singleactuator parameter cannot determine
the position of the joints as they are dependent on the contact state of each finger link with the object. This system
allows multiplelinksto adaptto the shape and location of an object passively usinga singleactuator,and hence are
considered as adaptive.Nearly 40% of the human hand’s functionality depends on the thumb, hence thumb design
is a critical parameter for upper limb prosthesis. Most of the prosthetic hands studied hear used thumb which is
actuated in extension/flexion and alongthecircumduction axis.To alternatebetween lateral grasp and power grasp,
the circumduction rotation of the thumb is required. Analysis of human hand kinematics showed an average
circumduction of 90.2o,achieved through a combination of three joints atthe baseof the thumb. The circumduction
axis of current hands is not always oriented parallel with the wrist rotation axis. By angling this axis ventrally or
dorsally,thumb flexion and circumduction rotation can bejointly approximated in a singleDOF.This can bebeneficial
to achieve desired hand openings and a more anthropomorphic motion for precision, power , and lateral grasp
patterns whilekeeping complexity low.
Grip force of the prosthesis is very important.Although most activities of daily livingrequirefastspeed and lowgrip
forces,there arealso occasionswhere the patient needs lowspeeds and high grip forces; hence, the prosthetic arm

15
should enablethe user to perform tasks which requireboth fastspeed and lowgrip forces,and slowspeed and high
grip forces.Itis difficultto predictthe necessary grasp forcerequired to maintain an objectwithin a particular grasp.
The required grasp force depends on friction between the object and the fingers, the object geometry and mass
properties, the number of contact points and the relativelocations of contacts. Human arm can reach up to 400 N
in power grasp and can exert 95.6 N of force in precision grasp.Based on previous studies,a grip force of 45-68 N is
sufficient to perform most activities of daily living. Based on an online survey carried out by previous researchers,
about 100% of females, 76% of males and 50% of children with amputation describetheir myoelectric prosthesis to
be slow. The typical speeds for everyday pick and placetasks is around 173-200o/s,but the human hand can reach
finger flexion speeds of 2290o/s if required. The finger flexion speeds of hands studied here ranged from 20o/s to
225o/s.The prostheses which belongto the upper portion of this rangearefine, but those which belong to the lower
portion of the range are quite slow in comparison to the actual human arm. Hence, i t was determined that it is
adequate to have arms which haveclosingtimerangingfrom0.8-1.5 s for most activities of daily livingthan anything
which has closingtimelarger than 1.5 s.
The typical activities of daily livingconducted by the amputees can be accomplished usinga finiteset of predefined
grasp patterns. These predefined grasp patterns include lateral, power, tripod, precision, finger point, and hook.
Some researchers also consider finger counting gesture as important besides the six gestures mentioned before.
Although the full range of distinct grasps for a normal hand is greater than thirty, these six grasps are the most
important in performing typical activities of daily living for the amputees. For the prosthesis to perform the six
grasping patterns mentioned, each individual finger flexion motion must be controlled using an actuator that is
independent of the other fingers in the prosthesis.If the function of finger counting is removed, the complexity of
the prosthesis and hence the requirement of multipleactuators can be reduced.
Durability is very important for the prosthetic arms.On average, a myoelectric prosthesis user wears the device in
excess of 8 hours per day. Hence, it is very important that the prosthesis is robustand comfortable enough for the
user to wear it for more than 8 hours. The designer of prosthetic arms must consider creating a balance between
durability,robustness,size,weight, and cost.To make the device robustand more functional withoutmakingitmore
complex or expensive, compliantcomponents likeconformingfingertips/palmarpads,actuator design thatincreases
compliance, and collapsible linkage systems can be included in the design. While a normal hand performs 2500 to
3000 grasping motions in a typical work day period of 8 hours, the prosthetic devices typically undergoes 120
graspingmotions in the same period of time. Even with low functionality of prosthetic hands compared to normal
hands,they should beableto withstand a total of 300,000 graspingcyclesand maintain all of its original functionality
for around 6 years of use. The current standard,which will actas the baseline,for prosthetic devices is the lifetime
of total 500,000 grasp cycles with routineservicingduringthe expected period of use.
2.4: CURRENT STATE OF THE ART
Current state of the art devices are extremely advanced, but not suited for customers’ needs. One form of
competition is known as the WPI Prosthetic Arm [53]. This arm is also a lightweight, low cost design that was very
similar to ours.Instead of usingmetals likenormal prosthetic arms,this design also uses plasticsto keep itlightand
cheap. However, our design differs becauseone of our primary objectives is comfort on top of the lightweight and
low cost materials. Additionally, our project will incorporate more temperature and pressure sensors in order to
operate the prosthetic arm likean actual armwould work.
Another similar itemcurrently on the market is theMichelangelo arm[54].TheMichelangelo armhas a very sensitive
touch and is one of the most advanced systems on the market. This product has larger degrees of freedom than a

16
majority of products on the market. However, becauseof that, the product is very expensiveand costs over $73,000.
Ideally,our team would liketo take similar technology from this device and use it in our design to make it efficient
whilestill beinexpensive.
Finally,our lastmajor competitiveproduct is the Bebonic arm[55]. The arm is very cutting age and smaller than the
normal prosthetic arm which means more lightweight. It has a high grip pattern and is the cheapest product on the
market with the most advanced technology. However, its cost is still extremely high compared to our budget.
Normally,this item is on the market for $11,000.
Table 1: General propertiesofprosthetic armscurrently available in the market.
Hand Competitor 1 Competitor 2 Competitor 3 Competitor 4 Competitor 5 Competitor 6
Weight (g) - 450-615 460-465 495-539 495-539 ~420
Overall Size - 180-182 mm
long, 75-80
mm wide, 35-
41 mm thick
180-182 mm
long, 75-80
mm wide, 35-
40 mm thick
198 mm long,
90 mm wide,
50 mm thick
190-200 mm
long, 84-92
mm wide, 50
mm thick
-
Number of
Joints
11 11 11 11 11 6
Degrees of
Freedom
6 6 6 6 6 2
Number of
Actuators
6 5 5 5 5 2
Actuation
method
DC Motor
with Worm
Gear
DC Motor
with Worm
Gear
DC Motor
with Worm
Gear
DC Motor
with Lead
Screw
DC Motor
with Lead
Screw
-
Joint
Coupling
Method
Linkage
spinningMCP
to PIP
Tendon
Linkage MCP
to PIP
Tendon
Linkage MCP
to PIP
Linkage
spanning
MCP to PIP
Linkage
spanning
MCP to PIP
Cam design
with links to
all fingers
Adaptive Grip Yes Yes Yes Yes Yes No*
*Adaptive grip in Competitor 5 is accomplished through adaptivemechanical coupling,and in others through
electronic torque control.
Here, DC = directcurrent, MCP = metacarpal phalange,PIP = proximal interphalange

17
Table 2: Grip and kinematic characteristicsofprosthetic armscurrently available in the market.
Hand Competitor
1
Competitor
2
Competitor
3
Competitor
4
Competitor
5
Competitor
6
Grip
Force
Precision
Grasp (N)
- 10.8 - 34 (tripod) 34 (tripod) 70
Power Grasp
(N)
- - 136 75 75 NA
Lateral Pinch
(N)
- 17-19.6 - 15 15 60
Range of
Motion
MCP Joints (o) 0-90 0-90 0-90 0-90 0-90 0-35
PIP Joints(o) 0-100 0-90 0-90 10-90 0-90 NA
DIP Joints (o) NA ~20 ~20 ~20 ~20 NA
Thumb
Flexion (o)
- 0-60 0-60 - - -
Thumb
Circumduction
(o)
- 0-95 0-95 0-68 0-68 -
Thumb
Circumduction
Axis
Parallel
with Wrist
axis
Parallel
with Wrist
axis
Parallel
with Wrist
axis
Parallel
with Wrist
axis
Parallel
with Wrist
axis
Compound
Axis
Grasp
Type
Finger/Grasp
Speed
- 200 mm/s 1.2 s in
power
grasp
1.9 s in
power
grasp,0.8 s
in tripod,
1.5-1.7 s in
key grasp
0.9 s power
grasp,0.4 s
tripod
grasp,0.9 s
key grasp
-
Achievable
Grasps
Power,
precision,
lateral,
hook,
finger point
Power,
precision,
lateral,
hook,
finger point
Power,
precision,
lateral,
hook,
finger point
Power,
precision,
lateral,
hook,
finger point
Power,
precision,
lateral,
hook,
finger point
Opposition,
lateral,and
neutral
mode
Here, DIP = distal interphalange,MCP = metacarpal interphalange,PIP = proximal interphalangeand NA = not
applicable

18
Figure 9: The Vincent Hand by Vincent Systems(Competitor 1).
Figure 8: The iLimb Hand by
Touch Bionics(Competitor 2).
Figure 10: The iLimb Pulse by
Touch Bionics(Competitor 3).
Figure 11: The Bebionic
Hand by RSL Steeper
(Competitor 4).
Figure 12: The Michelangelo hand
by Otto Bock (Competitor 6).
Figure 13: The BebionicHand v2 by
RSL Steeper (Competitor 5).

19
Figure 14: ImagesofFingersand Kinematic model joint coupling mechanism of
fingersstudied. (1)Vincent hand, (2)iLimb and iLimb Pulse, (3)Bebionic and
Bebionic v2, and (4)Michelangelo. Here, θ1 isthe angle ofmetacarpal phalange
joint and θ2 isthe angle ofproximal interphalange joint.
Figure 15: (1)The Central Drive Mechanism ofMichelangelo hand, (2)Placement ofmotor in Proximal Phalange, rotating worm against
fixed gear in Vincent hand, and (3)iLimb finger actuated in the same manner asVincent hand, but usesbevel gearsbetween worm drive
and motor. MCP =Metacarpal Phalange.

20
2.5: REGULATORY AND ECONOMIC CONSTRAINTS
Prosthetics fall under the Food and Drug Administration (FDA). The FDA claims that medical implants are devices
that are placed inside or on the surface of the body. In order to allow our device to be on the market, the FDA
requires itmustgo through numerous stages of testing. Oncethe deviceis fully developed,itwould still takemonths
to be able to go onto the market. However, it would ensure that our device is completely safe for the people who
may purchaseit.
The advantage of the device economically though is the fact that it would undercut almost every single other
prosthetic device on the market. Most upper limb prosthetics are well over $10,000 per device. Our device would
be highly customizable for each individual patient while still only costing approximately $1000 to produce. This is
significantly lower than the average priceof these products on the market.
2.6: ETHICAL, SAFETY, AND LIABILITY ISSUES
The main ethical issue is the idea that people would purposely jeopardize themselves in order to gain the same
advantages that they feel that someone with a prosthetic would have. Ethicists fear at one point that the amount of
advantages thatmay come from a prosthetic could makean averageperson become drastic enough to do something
in order to receive those same advantages. Now that there is an Olympic winning runner who has a prosthetic, it
raised theidea that maybe the prosthetic made iteasier for the winner to compete in the race. They feel a prosthetic
should havejustas many features as ittakes to mimic an actual armwithout too many mechanical advantages.
Safety issues for thisproductshould beminimal.Myoelectric sensors mustbeconnected to theclient’s arm,however
these can send small shocks to users. In order to combat this from happening in our product, the sensors will be
tested repeatedly to minimize errors. Additionally, sensors will be sewn into the sleeve, so the amount of direct
connect they will havewill lessen.The device runs at such low power, if someone were to get electrocuted from it,
they would experience an extremely small shock.Themaximum voltage this armwill run atis 7 Volts which is small.
These should be the only major electrical issues.For the mechanical side,the main safety issues would be the pinch
points.However, the product has been designed specifically to minimizethese in order to keep clients safe.
For prosthetics, the probability of liability is higher than that of medicine or nursing especially as the industry is
becoming more popular during times of war. Device malfunction can occur which could result in injury. However,
this is mostcommon in leg prosthetics becauseif they fail duringuse,itcould causethe clientto fall and experience
serious injury. For a prosthetic arm, there is a much lower risk. The prosthetic may give a small shock or pinch
someone if not used properly, but otherwise it should not be ableto hurt the user in malfunction.Additionally,the
computer science team intend to add a safeguard that would cause the arm to power down totally in case of a
malfunction.If the productwere to go on the market, the team would create a liability waiver.However, a core goal
of this experiment is the make the device as user friendly and safeas possible.

21
2.7: CLIENT SURVEY SYNOPSIS
In order to obtain more information about these issues firsthand,our team conta cted Ms. Anna Street of Brevard
Prosthetics. A majority of the questions had to do with the comfortability and the human factors to deal with the
project. She said confirmed most of what the casestudies said were true. When asked what the biggest factors to
consider are, she said the complaints she experienced was that the devices are hard to use and there is not much
comfortability. However, she claimed that expense of the prosthetic is not a big issue since insurance generally
covers the priceof the device.
The team also gained the ability to talk to more potential clients through the experience at the KEEN conference in
Tempe, Arizona. Clients liked the idea of having an arm centered on features that people wanted as opposed to
having something that was unnecessarily complex. The biggest complaint for most people is the fact that these
devices tend to be hard to use for the people that the devices are created for. Additionally, the devices are more
concentrated on the idea of getting more features developed as opposed to comfortability and aesthetics. After
discussingwith thevarious clients who may beinterested in this product,the main focuses theteam made was make
the hand as life-likeas possible(ie,aesthetically pleasing,temperatureand pressuresensor to understand what they
are touching), comfortable, and easy to use.

22
3: PRELIMINARY DESIGNS
Over the period of project requirements, definitions, research, and design modeling; elimination and refinement
took place repetitively to bring PriMA to its final design model. The architecture of the system is fabricated to aid
the customer in daily life experiences and shorten the technological gap keeping prosthetics from acting as real
human extremities, and flesh. Starting in a chronological order the process begins with muscle movement in the
residual belowelbowlimb of the patient. Myoelectric sensors arepositioned on top of specific musclegroups in this
area. These sensors recording micro muscle movements and convert them into a single analog di git such as
(1,2,3,4,5). This number is the sent through the circuit within the prosthesis to the processing board where it is
interpreted. The number passes through verifications for hand gesture patterns in the programming code until it
finally falls into a criterion to perform an operation. The processingboard then sends a signal to the linear actuator
design motors located in the wrist and fingers to conduct a motion which will elicit a gripping pattern; thus giving
the user the ability to use their brain to control the motion of their prosthesis.
To make the system more user friendly and comfortable a secondary system of sensors and equipment are
positioned to simulatethe sensation of feeling the objects being touched. Force Resistor Sensors are placed on the
fingertips of the hand alongwith temperature sensors.They are left in an open loop circuitwith 5 vibratingmotors
located back againstthe skin of the patient above the elbow. A voltage is sent to the sensors and when an objectis
gripped it alters thevoltage and sends the remainingelectricity to the user.Essentially thepatientcan feel how hard
they aregrippingan objectbecauseof the fluctuation in vibration of themotors receivingthe remainingpower from
the sensors.The temperature resistors will detectif the object in contact is hotor cold and lighta red or blue LED to
alert the user if the temperature is in a damaging range. Finally a Peltier Cooling device is located just above the
elbow as well to temporarily cool the patient’s blood flow and reduce anxiety of wearing a prosthetic.
3.1: APPEARANCE/MOD ULARIT Y
In the biomedical industry, it is of importance to maintain similarity to humanoid appendages when designing
prosthetics;therefore, the first,and most important, design consideration for PriMAis developinga functional arm
that looks as closeto a real armas possible. To establish realistic characteristics,we mapped each of our own arms
proportions as well as performed extensive research into the case studies of gender, race, and age group arm and
hand size. With these parameters, we were ableto develop a generalized model for any elbow down amputee that
we may work with. Further, we have determined that it is important to aesthetically design the exterior of the
prosthetic to resemble the skin tone and texture of the amputee. Thus, we have determined that the final product
will include a skin sleeve to better disguise the mechanical nature of the prosthesis. Given that 75% (citation) of
people prefer not to wear prosthetic arms they own, for a variety of reasons, which includes appearance, this will
allowus to better supportthe desires of more amputees.
3.2: DETERMINE PLATFORM
Given the viability of manufacturing low cost, mechatronic, prosthetic arms, we have determined that the best
avenue for driving our system is with micro DC motors, control boards, batteries, and sensors that are currently
readily availableto the public.

23
3.3: MOTORS
3.3.1: WRIST MOTOR
For the wrist, itquickly became clear that a dual shafted motor design would be necessary. The wristwill feel a lot
of torsion when the fingers or hand are exposed to a force, inducinga moment or torque. Havingone mechanism
drivingthe rotation of the wrist,as well as supportit, would not be ideal for this type of situation. At this point, we
began searchingfor motors with multipleshafts and satisfactory holdingtorqueto fitin theforearm. Stepper motors
are the best choicewith this form of application, but after research, they are very heavy, large, and expensive. The
weight of one of these devices largeenough for the application would makeit very uncomfortableto wear. This led
us to search for alternativeoptions that would still beableto hold various radial positions.
3.3.2: THUMB MOTORS
To keep the assembly hardware unified and simple, we came up with a way to use an analogue of the same N20
motors to drive the thumb. The lead screwis again connected to a threaded slider,but this slider will residein the
body of the thumb itself. To replicatethe many degrees of freedoms of the thumb, we will usea second N20 motor
to allow the thumb to traverse across the palm. This N20 motor will not have a lead screw, but will rather have a
standard motor shaft. A worm gear will be pressed onto this shaft. The proximal portion of the thumb will have
gear teeth printed onto the body for connecting to the worm gear. This will allow for precise movements of the
thumb, as well as great holdingtorque when not in motion.
3.3.3: FINGER MOTORS
After extensive research,we concluded that convertinga micro DC motor to a linear actuator,by useof a lead screw,
is the best compromise between all types of motors. To better match the torque capabilities of a linear actuator,
the DC motors need to be geared down significantly. Given these parameters,we quickly discovered theN-20, micro
DC motor with M4 lead screw shaft (as seen in Fig.) exceeded our requirements. In addition, these motors are
availablein many different gear ratios and operate within a voltage range of 3-12 V. A threaded slider,guided by a
pathway in the knuckles,pushes and pulls a connectinglinkagethatjoins the proximal finger digitto the slider.
Figure 17: Lead screw N20 brushlessDC motor. Figure 16: TamiyaDC motor parallel axisgearbox.

24
3.4: ELECTRONICS
3.4.1: SENSORS
While assessing how the user interface could be innovated from
previous models in the market to provide more accurate human
gestures, senses and mobility the team determined that the use of
sensory technology was essential.The main factor one would consider
when thinking of a human hand is the sense of touch. This is broken
down into the actual contactbetween the skin and a surfaceregarding
pressure and temperature. The best way for our team to reproduce
these capabilities in a dynamic prosthetic is to plant force and
temperature sensors atspecific locations within theextremity so that it
may benefit the user when in use. The 2.5 Kilo Ohm force resistors will
be placed in the distal finger digits of the thumb, pointer and middle
fingers. These sensors work as a resistor in a circuit that reduces the
voltage comingin based on how much pressureis applied to the sensor
pad (seen below in figure 4). The temperature resistive sensor (seen
below in figure5) will beplaced in thedistal finger digits of thepink and
ringfinger to gather a general temperature gage for any objectin which
the user may come in contact with. The software is designed to release
any objects that will begin to deform finger tips or sections of the arm
as well as light a blue or red LED based on whether the object would be
hot or cold to the human touch.
3.4.2: MYOELECTRIC
To allow the human intuition to power the bionic prosthesis, sensors
must be utilized to pick up brain or muscle activity that is directly
correlated with the maleficent arm. Whileimplantingthe human body
would be the most effective way to receive neural electrical pulsefrom
the remainingintactnervous system itis highly regulated and still deep
in the research and development stage. Thus the most viableoption for
PriMA was to select the Myoelectric Muscle Sensor V3 technologies.
These systems are cheap, readily available on the market and easy to
use. The system is comprised of a microcontroller alongwith 3 electrode sensor pads hooked to an analogJax cable.
The system takes all musclemovement through the skin at which itis attached and records it as a sinusoidal wave.
This wave is then transmitted to the microcontroller,which is preprogrammed to refine the signal into singleanalog
digits for the processing board to read. To effectively record motion for all five fingers and wrist control the final
model will incorporatetwo microcontrollerswith a total of 6 electrode sensors.
Figure 20: Temperature resistor.
Figure 18: Force-sensitive resistor.
Figure 19: Myoelectric sensor kit.

25
3.4.3: BATTERIES
The power supply for the entire system will consist of 1.2V Sub C class
Tenergy Nimh batteries wired in series together to produce a 6V charge
going into the boards and breadboards of the system. First the allows for
the batteries to be spaced throughout the system so that weight is evenly
distributed throughout the structure and so that space can be reserved.
This set up will allow the interface to function for a time constant of 5500
mAH. The table below shows the approximateuse of each electronic piece
of the system and how many Amps it will draw per hour, showing a final
estimated time for daily usein a typical work environment of 8 hours. The
Tenergy C cell batteries are also non memory forming cells and have a
recharge life of up to 1000 charges. These NiMh batteries were chosen
because they pose the least biological harm to the user and provide the
best power per spaceof any robotic battery source.
Table 3: Daily Battery Power Consumption
Electrical Component Quantity mAh Total mAh Percentage Used
per hr
Total Amps per
work day
N20 Motor 6 120 720 54% 3000
Force Resistor 3 0.136 .408 100% 3.264
Temperature Resistor 2 0.0915 .183 100% 2.916
Tamiya Gear Box Motor 1 120 120 41% 393.6
Arduino Uno 1 50 50 100% 400
Arduino Motor Shield V2 2 30 60 100% 480
VibratingCoin Motors 4 70 280 54% 302.4
Peltier CoolingDevice 2 200 400 12% 384
Myoelectric Controller and
Sensors
2 30 60 100% 480
Total mAh 5446.18
Figure 21: Tenergy NiMH battery cell.

26
3.4.4: PROCESSING BOARD
When addressingthe shear amount of electronics in our final model, PriMA needed a processingboard capableof
supplyingenough power, and data to each component in a timely and affordablemanner. Whilesearchingthrough
a largemajority of boards,microcontrollers and processorswedetermined the best option was to selectthe Adruino
uno (seen below in Figure 4). This board most importantly is essentially one of the few boards that fits within the
electrical core design space for our forearm. The board is installed with an ATMEGA328 8 bit microcontroller
processor with 32KB of ISP flash storage. This allows the Uno to be used for a variety of purposes which fit the
requirements of our sensory and mechanical system. The system was also selected for its uniquestack compatibility
with the arduino motor shield V2.The Uno contains 6 Analogpins,14 digital pins with 6 PWNpin outputs.The system
takes an input voltage from 6-12V and regulates it so that the processor and board runs on 5V. Given that we have,
3 force resistors,two myoelectric sensors (2 pins each), and 2 temperature resistors the arduino must be modified
with a DAC (digital to AnalogPin Converter) so that all of the sensors can berun properly and efficiently.
3.4.5: ARDUINO MOTOR SHIELD V2 MICROCONTROLLER
In able to run the majority of the electrical components within the prosthesis, microcontrollers must be installed
between the motherboard and their respective extremities in order to operate and control them in the proper
manner. PriMA’s final design prosthesis contains 7, bi-directional, DC motors which will all need to operate
independently from each other. The most effective way to produce these characteristics with in our interface is to
use two Arduino Motor Shield V2 microcontrollers.These microcontrollersaremostimportantly stackablewith the
Arduino uno, which brings the digital and analog pins from the motherboard up to the microcontroller so sub
systems can still beoperated (seen below in figure 7).The Motor Shields arecapableof running2 stepper motors or
4 DC motors bi-directionally.Sincetheseunits arestackablewe can stack onemotor shield on top of another to gain
access to 8 bi-directional DC motors all independently.
Figure 23: Stackable Arduino V2 Motor Sheild. Figure 22: Arduino Uno circuitboard.

27
3.6: STRUCTURE
3.6.1: FINGERS
Four-bar linkages and linearactuatorswill drivethefingers.
They are designed to be as slender and lifelike as possible
and while replicating the strength and gripping abilities of
human fingers.The tips of the fingers will contain forceand
pressure sensors set into holes designed into the tip
sections.Current finger prototypes are hollowed to fit the
linkages and wires. Future iterations will seek to minimize
the hollowspacethrough the middleof the fingers in order
to improve structural strength whilestill housingthewires
and linkages.Whilethecurrent prototypes are smooth, the
gripping surface may be textured in future iterations to
improve the fingers’ gripping ability. Ultimately, however,
skin-likecoverings will beput over the entire arm, possible
negating the need for a roughened gripping surface. To
further improve material strength, finger sections in future
iterations may be cast.This improves the material strength
by eliminating the layer separation inherent in many 3D
printingprocesses.
The fingers move usingfour-bar linkages and linearactuators.Theactuators push thebasesections whilethelinkage
moves along a curved path designed into the middle section of each finger. The current design uses spring-loaded
fingertips,which arepre-loaded,in a partially flexed position (essentially a torsional spring).As thehand grips objects
where use of the fingertips will becomecritical,the springwill extend and provideadditional grippingstrength.
3.6.2: PALM
The palm is the housing for the
driving mechanisms of the fingers
and thumb. This requires it to be
sturdy and durable while
remaining light. It was made
possible to fit five motors directly
onto the palm. Without the
separation of components,
pathways would be necessary to
squeeze the motors into place
ultimately creatingmany locations
of stress concentration across the
palm. Sincewe strayed away from one solid part,strongstructural ribs can beimplemented axially down the palm.
The knuckles arealso ableto be much stronger and supportiveof the motors. The pathways for the threaded sliders
would not have been possible without the extra build volume in the knuckles. These pathways are designed to be
Figure 24: Open hand gesture.
Figure 25: Closed hand gesture.
Figure 27: Palm and knucklesconnected. Figure 26: Palm and knucklesseparated.

28
rectangular which provides structural reaction moments on the sliders.Themotors boltdirectly to the knuckles,and
then bolts are used as the fasteners between the knuckles and the base. When the knuckles and palm base are
fastened together, the motors will besafely enclosed fromthe wearer of the prosthesis. Further,the motors can be
submerged into the structure of the palm. There is a lot of room for potentiometers, wiring, and other hardware
within the shell due to this. The base will also feature an enclosed wrist connection, which will give a streamlined
look and protect the wires from the control unit.The supportmaterial for thewristconnection is used for connecting
the thumb traversingmotor. The worm gear and gear teeth will notbeexposed to the skin coveringthemechanisms .
3.6.3: THUMB
The opposablethumb is one of the most complicated joints seen in nature. To be able to realistically replicatethe
ability of an opposable thumb, the prostheses thumb will utilize two of the previously described N20 motors. One
of the N20 motors will beused as a worm drivesystem to allowthethumb to traverseacross thepalm.This will end
up having a larger lateral range of motion than a human thumb for the user to learn and take advantage of. The
worm drivesystem will preventthe thumb from being pushed out of any location setby the user without deforming
the PLA itself. The second N20 motor will function similarly to the fingers using the M4 lead screw to convert the
rotational motion to linear motion with a threaded slider.
3.6.4: WRIST
The wrist will only have one degree of freedom allowing rotation. This is sufficient for the goal of creating an
affordable, feature full arm and allows for the wrist to accomplish its primary functions. The previously described
Tamiya worm gearbox will beused for connecting the forearm and palmtogether as well as controllingthe motion.
A hinge joint is used around the gearbox, completely concealing it and encasing the wires. This design has a nice
appearance,and looks similar to a human wrist.
3.6.5: FOREARM
In order to keep the operatingsoftware, boards and electronics in a safeenvironment for the user to use as well as
in an easy location to be manually worked on for maintenance and updates it had to be designed into a core
structure. Essentially thebatteries, boards,microcontrollers,heatsinks,and beard board arelocated in this area as
seen in the figurebelow. This coreis printed or cased similar in PLAjustliketheother pieces of the armand contains
3 natural heat transfer fins between the top and bottom layer. The outside surface will be coated in a silicon
dampening material to reduce all residual and largevibrational forces, which may be exerted on the system at any
point during its use. Having the electronics in a central core location allows the subsystem to be waterproofed so
that the customer cannot damage the electronics if any damp or wet materials come in contactwith the prosthesis
as well as allowing it to be operated in extremely humidified locations. Given the idea of performing maintenance
of the system it must obviously be ableto detach from the electrical system remainingin the structure of the arm
with ease and without damagingthe system. The only way to elicitthese properties is to have wire connection pins
located atthe inlets and exits of the corewhich allowthe microcontrollersand boardsto separatefromtheir outside
extremities.

29
The forearm will also contain theTamiya DC brushless Motor dual shaft gearbox, which will be located in the front
half of the final design.The gearbox motor is in position to power the wrist motion that the prosthesis is designed
for. The back sideof the forearm will contain thereceptor connection for the neoprene sleeve that will attach to the
user alongwith the cableinlets coming from the myoelectric sensors,coin motors, and Pelteir coolingdevices also
located in the sleeve.
3.6.6: NEOPRENE CONNECTION SLEEVE
As discussed in previous sections of the portfolio the retro fitting of the prosthesis to the patient is one of the most
difficultand crucial aspects of thedesign process.Thisinvolves thesensitivity of thepatient’s residual limb,structural
integrity of the entire weight of the final design and the process of sensor control.To ensure that all of these factors
were covered the only viablesolution for thesystemwas theuse of a custommade, skin tight,suction styleneoprene
sleeve. These sleeve as seen below will betightly pulled onto the customer’s residual limb and three quarters of the
way up the bicep muscle. Inside the neoprene sleeve and advanced network of electronics will be sewn into a
stationary place in the material. The myoelectric sensors will be located in the lower section of sleeve around the
forearm so thataccuratereadings can begathered and transmitted to the processingboard.On the Bicep and Tricep
portions of the sleeve, four coin motors will be position in a anatomical arrangement to allow the user to
comprehend then sensation of touch when the force resistor sensors located in the fingers come in contact with an
object. Finally closer to the elbow, two Pelteir coolingdevices will bepositioned around critical arteries so tha tblood
flow going towards the bottom of the residual limb can be cooled in its pathways.On the Joint end of the sleeve a
simple key way joint with pressure relieve ball socket is located in the center along with a circular cut out for all
electrical conduits to pass through.This will allow for a seamless connection between the two separate component
assemblies.
Figure 28: Wrist connection. Figure 29: Forearm and wrist assembly.

30
3.7: MATERIALS
3.7.1: POLYMER SELECTION
3D printing,for practical applications,utilizes polylacticacid (PLA) or acrylonitrilebutadiene styrene (ABS). ABS is a
more difficultto print as it must be extruded at a higher temperature than PLA; therefore, it is also more prone to
warpingduringmanufacturing.Our group selected PLA as the primary workingmaterial dueto how readily available
it is in the market as well as that most affordable3D printers only use it its fil ament source.This can be an issueas
it drastically decreases the durability and strength that the material would normally have if cast molded as a solid
part.
3.7.2: DAMPENING
In order to ensurethat our final productwill lastas longasits electrical aredesigned for we must reduce the amount
of vibrationsthateach board will undergo duringtheaverageday a user is wearingit.In order to do this a dampening
material must be placed between the electrical core and the outer structure of the forearm. The company 3M
supplies a viscoelastic dampening sheet which contains the properties we need to keep the system from being
damaged and also containsa sticky surfaceso that itcan be applied to anythingnecessary.
3.8: SIZE RESTRICTIONS
Sizeis oneof the most difficultrestrictionsto overcomewhiledesigningthis arm.Only so much can fitinto a confined
spacethat is small in volumeto begin with. The forearm houses the control unitfor the arm, so the forearm has to
be designed to be at leastas bigas the necessary control boards whileremainingatleastas small as to look normal
on an amputee. Luckily, the Arduino Uno with necessary expansion boards fits into the dimensions of an average
human forearm. However, the current design is only applicable to adults. It is planned to attempt to shrink the
system to the applications of children, but it is not considered for the first prototypes. The palm also runs into a
minimum size issue since it houses six N20 motors. As before, it would not be ideal to have the palm noticeably
larger than what the amputee originally had.
Figure 31: Neoprene sleeve with PriMA logo.
Figure 30: Schematicofelectrical componentsto be built into
the sleeve.

31
3.9: HUMAN FACTORS
3.9.1: HEALTH & SAFETY
PINCH POINTS
Pinch points are locations,usually hinged points, that skin or other extremities can get stuck in and sheared. In the
caseof largemachinery,these can be very dangerous;however; the worst that could happen with this prosthetic,if
it does happen, would only be an uncomfortable pinching sensation. This is still not desirable, so the joints will be
shielded as best as possible from the user. The wrist joint is completely concealed from human contact. The finger
joints are not as concealed as the wrist, but they should have no ability to pinch. Further, the artificial skin sleeve
that is intended to go over our own will eliminateany chances of the user contactinga pinch point duringeveryday
use.
ALLERGIES
PLA is derived from corn,but duringthe production of PLA the allergen,Profilin,is theorized to be destroyed and or
rendered inactive. There is no direct scholarly research behind this, but there is also no known human allergic
reaction to PLA. It is known, in many cases, that people with food allergies can eat food possessing the allergen
they’re allergic to after beingcooked becausethe allergen is denatured.This is truefor corn;therefore, itis assumed
to be true for PLA due to having never afflicted anyone and the heat required to produce it. However, we
recommend that patients with a corn allergy usecaution due to the ambiguity of knowledge. The processes used to
create this arm can easily supplementPLA for another material.This is recommended unless a doctor confirms that
PLA will notcausea reaction with a corn sensitiveamputee.
3.9.2: 3D SCANNING AND MOLD IMPRESSIONS
Below elbow disarticulation patients come from a variety of backgrounds, ages and genders such as battlefield
injuries,birth defects, or illness related surgeries. To account for the wide range of sizes and ligament proportions
one must develop a method to retrofit the prosthesis in a simpleand productivemanner. The most efficient way to
do this with a 3D printed system involves using a conventional 3D scanner. This technique allows the provider to
scan the patient’s residual limb and fitthe prosthesis to the exact sizenecessary to provideoptimal appearanceand
comfort.
3.9.3: BLOOD CIRCULATION
In order to test our hypothesis on providing sensory feedback to the user based on what they may touch with the
force resistors and the peltier coolingapparatus which both will be embedded in the sleeve. The most efficientway
of testingthis theory is to one use the arm seen below in figure1 as the main synthetic human device. The apparatus
contains all of the arteries,veins and musclestructures that any ordinary human extremity would have. Then using
the procedures documented in figure 3 one would perform the same below elbow disarticulation surgery to the
dummy arm.By re-creatinga patient's surgically removed arm,one would then be ableto apply thesleeve presented
in the final draft and test the original hypothesis. Essentially, the every time the force resistive sensors come in
contact with an object they will send the remaining voltage through the circuit to the Coin motors in the sleeve
which when then vibrateto the level of voltagecoming in. This would ultimately providethe user with the sensation
of touching objects with a non-human hand, as well as provide a level intensity for how hard the fingertips are

32
graspingsomethingdueto the variablevoltagecomingfromthe force resistors.This technology also acts asa system
which will circulate the blood of the patient within their respective attachment sleeve; ensuringthat blood will not
stagnate in the outer walls of the remaininglimb.This quality isessential to the customers because itprohibits their
limb from developing dead spots, and also keeps the muscle in the area healthy with fresh proteins and oxygen so
that they can trigger effective signalsinto the myoelectric sensors located further down the remaininglimb.
Figure 32: Basic below-elbow disarticulation amputation and human anatomy.
The second important aspect of the sleeve is the two Pelteir Thermoelectric Coolingdevices located justabove the
vibratingmotors.In normal prosthetic limbs where a user is provided with an attachments sleeve, not only does the
blood of the customer stagnate but it also perspires into the surroundingmaterial.This effect is a hazard one must
avoid when developing this system for multiple reasons. First the patient will begin to become extremely
uncomfortable wearingthe prosthesis if itpromotes sweat and heat build-ups in the surround extremity. Secondly,
when sweat is trapped between a foreign material and skin it typically begins to develop rashes and dead skin areas.
This is the worst scenario that can happen to a customer, as they will actually not be able to use their equipment
while the sore heals. Finally,if the sweat were capableof leakinginto the surround electronics it could potentially
damage the interfaceof the system or corrode itover time. The best way to avoid this isto position thesemicro heat
exchangers just above the vibrating coin
motors in the sleeve. This area of location will
ensure that all blood coming from the heart
and distantarteries is cooled before entering
the lower sections of the remaining limb. To
control this, a temperature resistor will be
also place in the sleeve so that In the event
that the arm rises above a normal
homeostasis it will automatically switch on
and begin to cool the area by up to over 20
degrees in a period of fiveminutes. There will
also be a temperature switch so that should
the user begin to become anxious of the heat
within their sleeve they can manually switch
the coolingdevices on to their digression.
Figure 33: Synthetic lab testing arm with artificial muscles, veins, and nerves.

33
When performing the lab testing, mass flow sensors and thermocouples will be placed at the inlet of the sleeve at
the top of the remaininglimb,the bottom of the remaininglimb,and the exit of the sleeve. Then Perfluorocarbons
or synthetic blood will beadded to the system at the samerate in which a heart would pump blood to the extremity
any typical human arm. These data collection devices will first record the system when the cooling and blood
circulating devices are NON-active to get a control. Then they will record at multiple levels of vibrational intensity
and coolingparameters to find the most effective and healthy circumstances for a patient's arm.
3.10: FAILURE FACTORS
Table 4: Failure Factors
Function Potential Failure Potential effects
from failure
Causeof Failure Problem
Addressed
Criteria
(100 scale)
Electrical
Command
System
Short Circuit
Switch Failure
Sensory Failure
Electrical system
stallsor breaks
Electrical System
stallsof breaks
Non -responsive
electrical system
Sporadic Involuntary
movement
Use of System
outsideof
Parameters
Broken Soldering
conduits
Broken Soldering
conduits
Sensors have worn
or blown as well as
bad solderingat
the board
connection port.
yes
yes
yes
7
2
8
Gestures Lifting
Gripping
Pulling
Droppingobject
being lifted
Object being gripped
slips of falls
Pulling of an object
fails
Force is larger than
specified restraints
yes
yes
yes
15
15
15
Sleeve Joint
Connection
Extensive Load Dislocatingfrom
limb
yes 15
Wrist
Connection
Extensive Load
Wear and Tear
Wriststructure
breaks or deforms
Pathway Jams/ stops
movement
Material wears
down
yes
yes
6
2

34
Daily Use Bumping
Falling
Electronic/
structural failure
over time
Complete structural
and electrical failure
Arm experiences
frequent small
forces
Impact is larger
than designed for
yes
yes
4
3
Motor Drive
System
Motor Stall Failure Mechanical system
seizes
Force applied is
larger than factory
specifications.
yes 8
3.11: MANUFACTURING
3.11.1: METHODS: 3D PRINTING VS. CASTING
SLA VS. FDM
There are currently two types of 3D printing techniques used in the entry level prototyping industry. The more
developed and common method is the Fused Deposition Modeling (FDM) 3D printing.This method simply heats up
a nozzle that melts down polymers from a spool as itisfed into thenozzle. The nozzle then “prints”out the 3D model
layer by layer. The process can print virtually any geometry with many different types of polymers, but PLA is
common and easy to use with this method. For further production of the arm,more polymers can be experimented
with if desired.See the figurebelow for a visual representation of FDMprintingsurfacecannotbeprinted. The layer-
by-layer process creates ridges that can be seen and felt on the final product.An example is shown below.
Figure 34: Dual-axisextrusion 3D printer.
Figure 35: Layer ridgesand separation.

35
3.12: ANALYSIS OF FUNCTIONALITY
3.12.1: STRESS ANALYSIS
The below Stress Analysis demonstrateVon Mises Stress simulation in SolidworksEdition 64.The color scaleseen in
the figures has been increased by 300-400% to give a more visually stimulatingexample.
3.12.2: THERMAL ANALYSIS
Given the robust electronic nature of PriMA’s final model, thermal characteristics of the product must carefully be
considered before entering a safe customer market. The entire mechanical armwill be fitted into a synthetic glove
that is aesthetically identical to the patients other extremities. This presents issue when determining where excess
heat produced by the batteries and all other electronics will bedisbursed to. To counter these effects the electrical
core located in the forearm as well as the palm and joint connection sleeve must be designed to release this heat
into the ambient surroundings. To begin with the electrical core where all of the boards, batteries and
microcontrollers are located will be filled with heat sinks which will draw the heat out of the system and into the
synthetic glove which will emit heat in the same manner skin will through pores or voids in the synthetic. The palm
will also contain heatsinks,which will pull heatfromthe motors in the knuckles out of the device and again into the
synthetic silicon glove.Finally the sleeve will consista neoprene synthetic material,which is unique in its ability to
pull moistureand heat from the inner surfaceand out the ambient surroundings.
Figure 36: Finger assembly simulation.
Figure 37: Knuckle simulation.
Figure 38: Linkage bar simulation.Figure 39: Slider joint simulation.

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