Design, model, prototype, test, analyse
and evaluate a mechanical human arm
(shoulder to wrist)

Year:

2006/07

Student: David Schroder

Course: BSc Engineering

Figure 1:

assembly of mechanical human arm

(

source

: Solid Edge, self-made)

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FACULTY OF COMPUTING, ENGINEERING &

MATHEMATICAL SCIENCES

(CEMS)

UNIVERSITY OF THE WEST OF ENGLAND

(UWE)

Design, model, prototype, test, analyse and

evaluate a mechanical human arm

(shoulder to wrist)

Student: David

Schroder

Course: BSc

Engineering,

Final

Year

Year:

2006/07

Module: Individual

Project

Module

No.:

UFMEAY-30-3

Date:

02.05.2007

Heading Sheet

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I. Summary

This study sets out to investigate, model and analyse a mechanical human arm. The

study consists of four main steps: the literature research, modelling the mechanical

human arm, building the model and finally analysing it.

The mechanical human arm is the same size as the real human arm of a 20-year-old

male. The range of motion is also the same.

The investigations cover the functionality of real human arms, the history of

prostheses, and applications of mechanical human arms in robotics. Requirements

that are based on these information are defined and lead to the first model. This

model is tested, rapid-prototyped and evaluated. Weaknesses are shown and an

improved model is developed. Analyses of stresses and strains support the design

decisions.

The model is designed in such a way that it is possible to add in further investigations

components such as motors, pneumatic or hydraulic elements in order to allow the

model to be part of a humanoid robot.

"No human investigation can be termed true science if it is not capable of

mathematical demonstration. "

Leonardo da Vinci

(1452 ­ 1519)

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II. Acknowledgements

Thanks to all those who have been involved in the investigations.

Thanks to Mr. Christopher Hart who helped me with the use of the Rapid-Prototyping

machines and other equipment in the CEMS labs.

Thanks to Neil Jones who helped me in producing some parts in the laboratory and

finding the right fasteners.

Thanks to Dr. Siamak Noroozi who explained how to use Visual Nastran 4D software.

Thanks to my friend Christian Abraham for his support related to this study.

Thanks to Mr. Rod Veazey whose CAD-course was very helpful to me in learning

how to use Solid Edge software.

Thanks to Mrs. Sue Scott for checking parts of the grammar.

Special thanks to my supervisor Dr. Gordon Smith for his help and guidance through

this study.

Additionally, I want to thank my brother Nicolas Schröder who gave me some good

technical advice for my work.

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III. Abbreviations, Terms, Symbols and Units

ABS

acrylonitrile

butadiene

styrene

Carpus

bones of the wrist

Glenohumeral

belonging to the shoulder joint

Humerus

the only bone of upper arm

Intercarpal

bones of the wrist towards the hand

Omoplate

bone of the shoulder (shoulder blade)

PVC

polyvinyl

chloride

Radius

the shorter bone of forearm

Ulna

the longer bone of forearm, lying at the side of the small fingers

Radiocarpal

bones of the wrist towards the forearm

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IV. Table of Figures

Page

Figure 1: assembly of mechanical human arm i

Figure 2: three-dimensional coordinate system 3

Figure 3: shoulder joint with omoplate and humerus 4

Figure 4: elbow joint with upper arm, radius and ulna bones 6

Figure 5: radius and ulna 7

Figure 6: wrist joint with radius, ulna and digital bones 8

Figure 7: prosthesis of arm of anonym wearer, 17th century 11

Figure 8: prosthesis of Götz von Berlichingen 12

Figure 9: "Sauerbruch-Arm" with bolt 12

Figure 10: prosthesis of the elbow joint before and after operation 14

Figure 11: ball and socket joints of prostheses 14

Figure 12: prostheses of the wrist joint 15

Figure 13: humanoid robot "Elektro" 17

Figure 14: humanoid robot "ASIMO" 17

Figure 15: anthropomorphic muscle robot ZAR 4 18

Figure 16: robotic arm of "ARMAR III", a robot built by students of Karlsruhe

University 19

Figure 17: movements of joints of the arm (excluding finger joints) 24

Figure 18: not yet finished shoulder joint of first version 32

Figure 19: upper arm part and forearm part 36

Figure 20: elbow joint (racked) 37

Figure 21: elbow joint (inflected) 37

Figure 22: wrist joint 39

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Figure 23: redesigned CAD-model of shoulder joint (with fasteners) 41

Figure 24: redesigned CAD-model of elbow joint (with fasteners) 42

Figure 25: redesigned CAD-model of wrist joint (with fasteners) 43

Figure 26: Fused Deposition Modelling machine during building process.

The head with the nozzles at the right side builds the part (white material) and

supports (brown material) 46

Figure 27: fastener of the first model that connects the elbow to forearm part to

the medial elbow part 47

Figure 28: all 70 fasteners of the physical model of the mechanical human arm

grouped by joints (shoulder: left bottom; elbow: right top; wrist: left top) 48

Figure 29: rapid-prototyped parts of the first model for assembly of shoulder joint... 49

Figure 30: first model of shoulder joint with screw contacting shoulder connection

part to omoplate, error marked with red rectangle 49

Figure 31: first model of shoulder joint with screw contacting shoulder to upper

arm part, error marked with red rectangle 50

Figure 32: rapid-prototyped parts for assembly of first model of elbow joint 50

Figure 33: first model of elbow joint with screw contacting elbow to forearm part,

error marked with red rectangle 51

Figure 34: rapid-prototyped parts for assembly of first model of wrist joint 51

Figure 35: first model of wrist joint with screw contacting wrist to hand part, error

marked with red rectangle 51

Figure 36: all rapid-prototyped parts of the redesigned model (all joints) 52

Figure 37: rapid-prototyped parts of the redesigned model for assembly of

shoulder joint 52

Figure 38: rapid-prototyped parts of the redesigned model for assembly of elbow

joint 53

Figure 39: rapid-prototyped parts of the redesigned model for assembly of wrist

joint 53

Figure 40: forearm part 67

Figure 41: upper arm part 67

Figure 42: central shoulder part of first model 68

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Figure 43: central shoulder part of redesigned model 68

Figure 44: shoulder angle part of first model 68

Figure 45: shoulder angle part of redesigned model 69

Figure 46: shoulder connection part to omoplate of first model 69

Figure 47: shoulder connection part to omoplate of redesigned model 69

Figure 48: medial shoulder ring part 70

Figure 49: shoulder to upper arm part 70

Figure 50: elbow to upper arm part 71

Figure 51: medial elbow part of first model 71

Figure 52: medial elbow part of redesigned model 71

Figure 53: elbow to forearm part of first model 72

Figure 54: elbow to forearm part of redesigned model 72

Figure 55: wrist to forearm part 73

Figure 56: wrist angle part 73

Figure 57: medial wrist ring part 73

Figure 58: wrist to hand part of first model 74

Figure 59: wrist to hand part of redesigned model 74

Figure 60: shoulder joint: 0° extension, 60° lateral rotation, medial shoulder ring

part and shoulder to upper arm contact shoulder angle part, side view 75

Figure 61: shoulder joint: 0° extension, 60° lateral rotation, medial shoulder ring

part and shoulder to upper arm contact shoulder angle part, top view 75

Figure 62: shoulder joint: 0° extension, 70° medial rotation, medial shoulder ring

part and shoulder to upper arm contact shoulder angle part, side view 75

Figure 63: shoulder joint: 0° extension, 70° medial rotation, medial shoulder ring

part and shoulder to upper arm contact shoulder angle part, top view 76

Figure 64: shoulder joint: 0° flexion/extension, 0° lateral/medial rotation, neutral

position, side view 76

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Figure 65: shoulder joint: 65° extension, 0° lateral/medial rotation, shoulder to

upper arm part and shoulder connection part to omoplate contact each other,

side view 76

Figure 66: shoulder joint: 90° flexion, 60° lateral rotation, shoulder to upper arm

part and shoulder connection part to omoplate contact each other, medial

shoulder ring part and shoulder angle part contact each other, side view 77

Figure 67: shoulder joint: 90° flexion, 60° lateral rotation, shoulder to upper arm

part and shoulder connection part to omoplate contact each other, medial

shoulder ring part and shoulder angle part contact each other, top view 77

Figure 68: shoulder joint: 90° flexion, 70° medial rotation, shoulder to upper arm

part and shoulder connection part to omoplate contact each other, medial

shoulder ring part and shoulder angle part contact each other, side view 77

Figure 69: shoulder joint: 90° flexion, 70° medial rotation, shoulder to upper arm

part and shoulder connection part to omoplate contact each other, medial

shoulder ring part and shoulder angle part contact each other, top view 78

Figure 70: shoulder joint: 165° flexion, 0° lateral/medial rotation, shoulder to upper

arm part and shoulder connection part to omoplate contact each other, side view .. 78

Figure 71: elbow joint: 0° extension, 0° pronation/supination, neutral position,

elbow to upper arm part and medial elbow part contact each other, side view 79

Figure 72: elbow joint: 0° extension, 0° pronation/supination, neutral position,

elbow to upper arm part and medial elbow part contact each other, top view 79

Figure 73: elbow joint: 0° extension, 95° pronation, elbow to upper arm part and

medial elbow part contact each other, elbow to forearm part and medial elbow

part contact each other, side view 79

Figure 74: elbow joint0° extension, 95° pronation, elbow to upper arm part and

medial elbow part contact each other, elbow to forearm part and medial elbow

part contact each other, top view 80

Figure 75: elbow joint: 150° flexion, 0° pronation, elbow to upper arm part and

medial elbow part contact each other, side view 80

Figure 76: elbow joint: 150° flexion, 95° pronation, elbow to upper arm part and

medial elbow part contact each other, elbow to forearm part and medial elbow

part contact each other, side view 80

Figure 77: elbow joint: 150° flexion, 95° pronation, elbow to upper arm part and

medial elbow part contact each other, elbow to forearm part and medial elbow

part contact each other, top view 81

Figure 78: wrist joint: 0° flexion/extension, 0° abduction/adduction, neutral

position, side view 82

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Figure 79: wrist joint: 0° flexion/extension, 0° abduction/adduction, neutral

position, top view 82

Figure 80: wrist joint: 0° flexion/extension, 20° abduction, medial wrist ring part

and wrist angle parts contact each other, side view 82

Figure 81: wrist joint: 0° flexion/extension, 20° abduction, medial wrist ring part

and wrist angle parts contact each other, top view 83

Figure 82: wrist joint: 0° flexion/extension, 36° adduction, medial wrist ring part

and wrist angle parts contact each other, side view 83

Figure 83: wrist joint: 0° flexion/extension, 36° adduction, medial wrist ring part

and wrist angle parts contact each other, top view 83

Figure 84: wrist joint: 73° extension, 0° abduction/adduction, wrist to hand part

and medial wrist ring part contact each other, side view 84

Figure 85: wrist joint: 73° extension, 0° abduction/adduction, wrist to hand part

and medial wrist ring part contact each other, top view 84

Figure 86: wrist joint: 75° flexion, 0° abduction/adduction, wrist to hand part and

medial wrist ring part contact each other, bottom view 84

Figure 87: wrist joint: 75° flexion, 0° abduction/adduction, wrist to hand part and

medial wrist ring part contact each other, side view 85

Figure 88: central shoulder part, both shoulder angle parts and shoulder

connection part to omoplate; force (50N, z-direction) applying to the surfaces of

the shoulder angle parts that limit lateral rotation 86

Figure 89: elbow to forearm part; force (100N, y-direction) applying to the surface

that limits supination/pronation 86

Figure 90: elbow to upper arm part; force (100N, -y-direction) applying to the

surfaces that limit flexion 87

Figure 91: medial elbow part; force (100N, y-direction) applying to the surface that

limits supination/pronation 87

Figure 92: medial shoulder ring part; force (100N, -x-direction) applying to the

surfaces that limit lateral/medial rotation 88

Figure 93: medial wrist ring part; force (25N, y-direction) applying to the surfaces

that limit flexion 88

Figure 94: shoulder connection part to omoplate; force (300N, -y-direction)

applying to the surfaces that limit flexion 89

Figure 95: shoulder to upper arm part; force (100N, x-direction) applying to the

surfaces that limit flexion/extension 89

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