Thesis

The Mechanical Design of a Humanoid Robot

By

Anthony Hunter

(Supervisor : Gordon Wyeth)

Undergraduate Thesis

19 October 2001

Department of Computer System Engineering

University of Queensland

A M Hunter 4 Vonne Ct Camp Mountain QLD 4520 Prof. Simon Kaplan, Head of School of Information Technology and Electrical Engineering University of Queensland St. Lucia QLD 4072 Der Sir In partial fulfilment of the requirements for the Bachelor of Engineering Degree, I Hereby submit this thesis entitled � The Mechanical Design of a Humanoid �. Yours faithfully Anthony Hunter

Mechanical Design Of A Humanoid

Anthony Hunter i

Acknowledgements Many people contributed to this thesis in one way or another. Here I give a list of those who I can

remember assisting me. I would like to thank:

• My parents and family for their unconditional support throughout the year.

• Gordon Wyeth my thesis supervisor.

• The Mechanical Workshop, especially Keith, Wayne and Bill for their guidance into

manufacturing processes and general assistance.

• Dr V. Kippers of the Anatomy Department for his help on finding references for human walking

and the anatomy of the human body.

• Tony Schmidt from SKF bearings.

• The GuRoo thesis team for there friendly approach to team work


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Abstract

Designing and building robots that are capable of bipedal motion has become an increasingly

central goal to engineers and researcher alike. This is because of its varied uses including the

possibilities of helping the aging populous achieving every day choirs. Bipedal motion is a fairly

complex motion in humans, and even harder to simulate exactly using mechanical structures.

It is for this reason that the Strategic Goal of this thesis is to simulate the human gait as closely as

possible using a variety of mechanical structures and components. The humanoid robot known as

the GuRoo has been especially designed to achieve this goal. Version 1.0 of the GuRoo has been

designed in Solid Edge. The skills required to design the GuRoo came from many various

disciplines, including Electrical Engineering, Mechanical Engineering, Anatomy and the

Department�s Mechanical and Electrical Workshops. In unison, these skills provided the

knowledge to create a feasible design that can be manufactured and is capable of walking.

The Mechanical side of the GuRoo is still in the manufacturing process in the Department�s

Electrical Workshop after being fully design. At present the lower legs and mechanical bosses have

been manufactured.

Future Directions for the GuRoo robot include such facets as installing internal sensors into the foot

for calibrations during walking, upgrading of the foot, completion of the manufacture, installation

of the circuitry for testing and development of the simulator results and control loops.


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Table Of Contents ACKNOWLEDGEMENTS i ABSTRACT ii TABLE OF CONTENTS iii LIST OF TABLES AND FIGURES vi

CHAPTER 1 - INTRODUCTION................................................................................................................................... 1

1.1 INTRODUCTION ......................................................................................................................................................... 1 1.2 WHAT THIS THESIS ENTAILS .................................................................................................................................... 2 1.3 GENERAL MECHANICAL CHARACTERISTICS OF THE GUROO .................................................................................... 2

1.3.1 Human Characteristics .................................................................................................................................... 3 1.3.2 Lightweight....................................................................................................................................................... 3 1.3.3 Actuators .......................................................................................................................................................... 3 1.3.4 Ascetically Pleasing ......................................................................................................................................... 3

1.4 THE DESIGN AT PRESENT.......................................................................................................................................... 4 1.5 SUMMARY OF THE MECHANICAL DESIGN OF A HUMANOID THESIS .......................................................................... 4

1.5.1 Chapter 1.......................................................................................................................................................... 4 1.5.2 Chapter 2.......................................................................................................................................................... 4 1.5.3 Chapter 3.......................................................................................................................................................... 4 1.5.4 Chapter 4.......................................................................................................................................................... 5 1.5.5 Chapter 5.......................................................................................................................................................... 5 1.5.6 Chapter 6.......................................................................................................................................................... 5 1.5.7 Chapter 7.......................................................................................................................................................... 5 1.5.8 Appendices ....................................................................................................................................................... 5

CHAPTER 2 - LITERATURE REVIEW...................................................................................................................... 6

2.1 THE HONDA HUMANOID........................................................................................................................................... 6 2.1.1 Evolution of the Honda Robots ........................................................................................................................ 7

2.2 THECODONT-BIPEAL WALKER ................................................................................................................................. 8 2.3 HUMAN CHARACTERISTICS ...................................................................................................................................... 9 2.3.1 THE HUMAN FORM ................................................................................................................................................ 9 2.3.2 THE APPENDICULAR SKELETON ............................................................................................................................ 9

2.3.2.1 The Pectoral Girdle..................................................................................................................................... 11 2.3.2.2 The Upper Limbs......................................................................................................................................... 11 2.3.2.3 The Pelvic Girdle ........................................................................................................................................ 12 2.3.2.4 The Lower Limbs......................................................................................................................................... 13

2.3.3 THE AXIAL SKELETON......................................................................................................................................... 15 2.3.3.1 The Skull...................................................................................................................................................... 15 2.3.3.2 The Thoracic Cage...................................................................................................................................... 15 2.3.3.3 The Vertebral Column................................................................................................................................. 16

2.4 THE CAUCASIAN MALE .......................................................................................................................................... 17

EXAMPLE 2.1 ................................................................................................................................................................ 17

2.5 HUMAN WALKING .................................................................................................................................................. 19 2.6 PELVIC ROTATION .................................................................................................................................................. 21 2.7 PELVIC LIST............................................................................................................................................................ 21

CHAPTER 3 - DESIGN SPECIFICATIONS .............................................................................................................. 21

3.1 DEFINITION OF HUMANOID..................................................................................................................................... 21 3.2 DESIGN SPECIFICATIONS......................................................................................................................................... 23 3.3 THE UPPER BODY ................................................................................................................................................... 23

3.3.1 The Head ........................................................................................................................................................ 24 3.3.2 The Neck......................................................................................................................................................... 24 3.3.3 The Torso ....................................................................................................................................................... 24 3.3.4 The shoulders ................................................................................................................................................. 25


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3.3.5 The Upper Arm............................................................................................................................................... 25 3.3.6 The Elbow ...................................................................................................................................................... 25 3.3.7 The Lower Arm............................................................................................................................................... 25

3.4 THE LOWER BODY.................................................................................................................................................. 26 3.4.1 The Waist........................................................................................................................................................ 26 3.4.2 The Hip........................................................................................................................................................... 26 3.4.3 The Leg Abduction ......................................................................................................................................... 26 3.4.4 The Leg Flexion.............................................................................................................................................. 26 3.4.6 The Lower Leg................................................................................................................................................ 27 3.4.7 The Ankle........................................................................................................................................................ 27 3.4.8 The Foot ......................................................................................................................................................... 27

3.5 TYPES OF ALUMINIUM ............................................................................................................................................ 28 3.5.1 The 6000 Series .............................................................................................................................................. 28 3.5.2 The 7000 Series .............................................................................................................................................. 28

3.6 BEARINGS............................................................................................................................................................... 29 3.6.1 Principles of Bearing Selection and Applications.......................................................................................... 29

3.7 BOSSES ................................................................................................................................................................... 30

CHAPTER 4 � GUROO IMPLEMENTATION.......................................................................................................... 31

4.1 THE UPPER BODY ................................................................................................................................................... 31 4.1.1 The Head ........................................................................................................................................................ 32 4.1.2 The Neck......................................................................................................................................................... 33 4.1.3 The Torso ....................................................................................................................................................... 33 4.1.4 The Shoulders................................................................................................................................................. 34 4.1.5 The Elbow ...................................................................................................................................................... 37

4.2 THE LOWER BODY.................................................................................................................................................. 38 4.2.1 The Waist and Spine....................................................................................................................................... 38 4.2.2 The Hip........................................................................................................................................................... 41 4.2.3 Upper Leg Abduction ..................................................................................................................................... 42 4.2.4 The Leg Flexion.............................................................................................................................................. 43 4.2.5 The Upper Leg................................................................................................................................................ 44 4.2.6 The Lower Leg................................................................................................................................................ 45 4.2.7 The Ankle........................................................................................................................................................ 46 4.2.8 The Foot ......................................................................................................................................................... 46

4.3 COMMON PARTS ..................................................................................................................................................... 47 4.3.1 Bosses............................................................................................................................................................. 47 4.3.2 The Motor Assembly....................................................................................................................................... 47 4.3.3 Spigot ............................................................................................................................................................. 48

CHAPTER 5 - SOFTWARE IMPLEMENTATION................................................................................................... 49

5.1 EQUATIONS OF MOTION FOR A RIGID BODY ........................................................................................................... 49 5.2 ANGULAR MOMENTUM OF A RIGID BODY IN PLANE MOTION ................................................................................ 50 5.3 ANGULAR MOMENTUM OF A RIGID BODY IN THREE DIMENSIONS. ........................................................................ 50 5.4 RETRIEVING DATA FROM SOLID EDGE FOR INERTIA TENSORS ............................................................................... 51

CHAPTER 6 - PRODUCT EVALUATION................................................................................................................. 53

6.1 DESIGN PROCESS OF LOWER LEG ........................................................................................................................... 54 6.2 DESIGN OF THE 12MM BOSS.................................................................................................................................... 56 6.3 HOW WELL I PERFORMED....................................................................................................................................... 57

CHAPTER 7 � FUTURE DEVELOPMENTS ............................................................................................................. 58

7.1 IMPLEMENTATION OF GUROO VERSION 2.0............................................................................................................ 58 7.2 CONCLUSION .......................................................................................................................................................... 58


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APPENDICES APPENDIX A BIBLIOGRAPHY APPENDIX B BONE SHAPES APPENDIX C ALUMINIUM DATA SHEETS APPENDIX D NMB BEARING SHEETS APPENDIX E UNBRAKO SCREWS APPENDIX F DEFINITIONS APPENDIX G PLANE OF SECTIONS


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Figures Figure 2.1 The Honda Humanoid Robots 7 Figure 2.2 - The Appendicular Skeleton 10 Figure 2.3 � Anterior View Of The Right Pectoral Girdle 11 Figure 2.4 � Divisions Of The Pelvis 13 Figure 2-5 � The Axial Skeleton 15 Figure 2.6 � The Vertebrae Column 18 Figure 2.7 � Displacement Of Human Limbs During Normal Human Walking 22 Figure 2.8 - Displacement Of The Centre Of Mass In Human Walking 22 Figure 2.9 - Diagram Of The Effects Of Pelvic Rotation 23 Figure 2.10 - Diagram Of The Effects Of Pelvic List 24 Figure 3.1 � Definition of the Humanoid Size 26 Figure 3.2 � Diagram of the degrees of freedom 27 Figure 3.3 � Bearing Types 34 Figure 4.1 � The Head and Neck Assembly 37 Figure 4.2 � The Torso Assembly 39 Figure 4.3 � The Shoulder Hi-Tech Servo Motor Connection 40 Figure 4.4 � The Shoulder Assembly 41 Figure 4.5 The Elbow and Arm Assembly 42 Figure 4.6 The Waist and Spine Assembly 43 Figure 4.7 - The Pitch Assembly 44 Figure 4.8 - The Pitch � Roll Assembly 45 Figure 4.9 � The Yaw Assembly Attachment to the Torso 46 Figure 4.10 � The Under Side of The Hip 47 Figure 4.11 � The Leg Abduction 48 Figure 4.12 � The Flexion Assembly 49 Figure 4.13 � The Upper Leg Rotation Assembly 50 Figure 4.14 - The Lower Leg Assembly 51 Figure 4.15 - The Ankle 52 Figure 4.16 � The Foot Assembly 53 Figure 4.17 � The Boss Assembly 54


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Figure 4.18 � The Motor Assembly 55 Figure 4.19 � Spigot for Thrust Bearing Locating 56 Figure 5.1 - Rigid Body Acted Upon By Several External Forces 57 Figure 6.1 � Boss, Motor, Lower Leg Setup 61

Figure 6.2 � The Guillotine 62 Figure 6.3 � The Exact Hole Being Cut On The Using A Boaring Head On The Milling Machine 63 Figure 6.4 � Broach Set : Guide, Broach and Depth pin 64 Figure 6-5 The 12mm Boss 65 Tables Table 1-1 GuRoo Team Members Description 1 Table 2.1 - Trotter Gleser Regression Formulas for a Caucasian Male 19 Table 2.2- Scaled Human Lengths of Limbs for a Caucasian Male 20 Table 5.1 - Densities of Materials Used 57


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Chapter 1 - Introduction

1.1 Introduction

There has been varied research into bipedal and humanoid walking in the past. Most of which is

based around human motion through powered actuation of joints as well as some purely mechanical

based actuation. This existing research provides a useful basis for the design of University of

Queenslands first walking humanoid robot called the GuRoo.

The team designing, creating electrical circuits and software for the GuRoo consists of twelve

members who each have a specific role to play in the eventual walking of the GuRoo.

The twelve member�s roles for the GuRoo project are listed in Table 1.1.

GuRoo Team Member

Member Thesis Description

Mark Wagstaff Mechanical Design and Internal Sensors for a Humanoid Damien Kee Design and Simulation of a Humanoid Drive System Anthony Hunter Mechanical Design of a Humanoid Nathaniel Brewer Power System for a Humanoid Tim Cartwright Design and Implementation of Small Scale Joint Controllers for a

Humanoid Robot Jarad Stirzaker Design of DC Motor Controllers for a Humanoid Robot

Bartek Bebel USB to CAN Bridge for Humanoid Project Shane Hosking High Speed Peripheral Interface Andrew Smith Simulator Development and Gait Pattern Creation for a

Humanoid Robot Emanuel Zelniker Joint Controllers for a Humanoid Robotic Limbs David Prasser Vision Software for Humanoid Robot Soccer Andrew Blower Development of a Vision System for a Humanoid Robot

Table 2-1 GuRoo Team Members Description The strategic goal of the team is to create a three dimensional humanoid robot that is capable of

standing freely and walking. The tactical goal of the team in creating the GuRoo, is to design a

humanoid robot that is capable of walking at a pace of 0.1m/s. The tactical goal is well within the

capability of the team. The operational goal of the GuRoo is to create a humanoid robot that is

capable of playing robot soccer by incorporating vision hardware and software from the University


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of Queensland�s ViperRoos Soccer Team. The RoboCup Humanoid Robot Soccer Competition

will be against various competing university�s from around the world and against such

organisations as Sony and Honda, who both have been researching the walking of humanoid robots

for some years.

1.2 What This Thesis Entails

This thesis describes the mechanical design of the University of Queensland�s first humanoid robot

called the GuRoo. The Mechanical design team that includes Mark WagStaff, Damien Kee and

myself Anthony Hunter will design this first humanoid robot. The design of the GuRoo will start

from first principles.

The GuRoo will be constructed using simplicity of manufacture with the possibility of quickly

building a team of humanoid robots. It is for this reason that the GuRoo Project should be as cost

effective as possible.

This thesis will discuss the mechanical arrangements of links and joints, discuss the integration of

the mechanical design with actuators, discuss mechanical component selection, and outline details

of manufacture of the robot.

1.3 General Mechanical Characteristics of the GuRoo The GuRoo humanoid robot was primarily modelled around normal human motion. There were

several reasons for this model:

• There is vast amounts of data on the principles of human walking

• There is forensic anthropological data for ideal human walking characteristics

• This is the best method to undertake for reproducing bipedal motion.


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As this thesis concentrates on documenting the Mechanical Design of the Humanoid it was

important to create some general design parameters.

1.3.1 Human Characteristics

The GuRoo needed to look and act like a human as humanly possible. This includes such factors as

the ascetics of the GuRoo, the proportions of the limbs, the movement of the GuRoo and how the

joints respond in critical situations.

1.3.2 Lightweight

The humanoid needs to be as light as possible for the actuators to work efficiently and with minimal

strain. For this reason the majority of the humanoid is made from 3.125mm-plate aluminium. This

type of aluminium provides good strength properties, as well as being easily shaped and formed in

manufacture. The design of the GuRoo is to be approximately 30kg.

1.3.3 Actuators

The GuRoo is to be an active robot. This requires the joints to be powered by electric motors.

Using electric motors for actuation will allow clean, efficient movement for a range of movements

that will enable the humanoid to mimic human locomotion.

1.3.4 Ascetically Pleasing

The humanoid robot needs to look like a complete unit. This entails cover plates for the limbs that

conceal the PCB�s and wiring beneath, colouring, and a head that generally resembles humans. All

of the wiring and PCB�s are housed within the mechanical limbs.


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1.4 The Design at Present

As of Wednesday October 17, the parts of the GuRoo that have been manufactured are two lower

legs and all the mechanical bosses used to connect the motors to the various links. The designs for

all other pieces have been fully designed and drafted in Solid Edge and have been handed to the

workshop awaiting construction.

1.5 Summary of the Mechanical Design of a Humanoid Thesis

1.5.1 Chapter 1

Chapter 1 provides a plan for the creation of the GuRoo Humanoid Robot. It does this by listing the

strategic, tactical and operation goals for the team and defines some general characteristics of the

GuRoo robot.

1.5.2 Chapter 2

Chapter 2 details how bipedal and humanoid robots have been develop in the past and what can be

learnt from those efforts. Chapter 2 also provides background information on the human form

including bone structure and how they combine within the human skeleton. This chapter also details

how the human body performs the walking motion.

1.5.3 Chapter 3

Chapter 3 details the process of how the GuRoo was broken down into different components of the

body to be designed. This chapter provides background information on the parts and materials that

are going to be used in the design of the GuRoo. This includes bearings, bosses and types of

aluminium.


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1.5.4 Chapter 4

Chapter 4 details the mechanical design of the GuRoo using Solid Edge. Specifically providing

information on the construction of components, integration of limbs with actuators and the materials

used.

1.5.5 Chapter 5

Chapter 5 describes how the parts designed in Solid Edge were modelled and simulated in Solid

Works. This chapter also describes the principles behind the simulations.

1.5.6 Chapter 6

Chapter 6 describes how the parts that have been manufactured so far have been manufactured in

the workshop. It details the processes used in manufacture and the machines and tools that were

used.

This chapter also explains my personal strengths and weaknesses in designing the GuRoo.

1.5.7 Chapter 7

Chapter 7 explains possible future development and upgrade to the GuRoo. It also describes what I

would do the same and what I would do differently and provides a conclusion for this thesis.

1.5.8 Appendices

The Appendices includes the Bibliography of the thesis, data sheets of materials and components,

definitions of various terms and features.


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Chapter 2 - Literature Review 2.1 The Honda Humanoid

The Honda Humanoid Robot, The Honda Humanoid Robot [1], research began in 1986 with a

development program. The concept behind the commencement of the program was to create a

robot that could �coexist and cooperate with human beings, by doing what a person cannot do and

cultivating a new dimension immobility both of which would add value to society.� The robot is

designed to perform such functions as going up and down stairs.

The engineers at Honda began their research on the �foot/leg walking mobile function,� which

corresponds to basic human mobility.

The studies that were conducted were:

1) Movement of leg/foot joints when walking

2) Joint alignment

3) Dimensions, weights and centres of gravity of each leg and foot

4) Torque application to the joints when walking

5) Sensor systems required for walking

6) Landing impact when walking

For the data gathered from the research into these areas the Honda Engineers were able to develop a

model for stable walking. The model for stable walking worked by applying pressure to a part of

the plantar to avoid falling while walking and at standstill. If the sensors judged that the pressure is

not enough to keep the robot stable, the movement of mechanical limbs would alter the centre of

gravity.


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2.1.1 Evolution of the Honda Robots

The first Honda humanoid prototype, P1, was 1,915 mm in height and weighed 175kg. The P1

aided in identifying the most efficient method of synchronising arm/leg movements. The P1 was a

successful project that achieved all of it strategic goals.

The second Honda robot was a more sophisticated robot that achieved a freer range of movement

than the P1. The P2 stood at 1,820mm in height and weighed 210kg. It was able to go up and

down stairs and push a vehicle, all of which was triggered via a wireless transponder.

The latest version of the prototype is the P3. The P3 is the most compact version yet, with a height

of 1,600mm and a weight of 130kg.

Figure 2.1 The Honda Humanoid Robots


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2.2 Thecodont-Bipeal Walker The goal of the Condont robot The Condont [2] was to design a robot that could walk without

toppling over using 12 individually controlled motors. This would be achieved by controlling each

motor individually to counteract moments produced on the structure.

The Condont was originally constructed using 8082/5T aluminium because of its high strength and

low weight properties, and it stood at 60cm tall and 30cm wide. It was one of the first bipedal

walking robots in its price range.

The structures of the legs were very simplistic being composed of rectangular prisms made from

lengths of aluminium to simulate the legs up to the hip region. This would have made the process

of walking more complex as the centre of mass of a human is located around the pelvis with the

arms aiding in balance.

The control housing system for the robot is located at the pelvis region. It contains the PCB�s for

the control of the robot, and in itself is fairly heavy relative to the rest of the robot. This makes the

task of controlling the mechanical structures even harder as the robot is top heavy.

In summary the Condont is a good example of linking mechanical structures but as a complete unit

it isn�t capable of successful walking over long distances.


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2.3 Human Characteristics

There is a wealth of information relating to both the anatomy of a human and human motion.

Therefore this was a good starting point in trying to model the walking characteristics of the

humanoid robot. The first point to investigate is how the human body is constructed. The reference

book, Fundamentals of Anatomy and Physiology [3] proved a good source of information on this

topic. The next point to investigate was how human walk in a bipedal fashion. This information

was acquired from the reference book Human Walking [4].

2.3.1 The Human Form Each of the different parts of the human skeleton is designed to perform a particular function. For

example the skull protects the brain and also the eyes and ears. For this reason the extremities of

the human torso will form a basis for the humanoid design.

The appendicular skeleton of the human body includes the bones of the limbs and the supporting

elements, or girdles, that connect them to the trunk. The appendicular skeleton is dominated by the

long bones that support the limbs Bone Shapes [Appendix B].

Each long bone shares common features with other long bones. For example, one epiphysis (the

head of the long bone) is usually called the head, the diaphysis (the shaft of a long bone) is called

the shaft, and a neck normally separates the head and shaft.

2.3.2 The Appendicular Skeleton

The Appendicular Skeleton can be broken into four major groups. These group are the Pectoral

Girdle that contains four bones, the Upper Limbs that contains sixty bones, the Pelvic Girdle that

contains two bones and the Lower Limbs that also contain sixty bones (Figure 2.2 - The

Appendicular Skeleton).


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Figure 2.2 - The Appendicular Skeleton


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2.3.2.1 The Pectoral Girdle

Each arm forms a joint with the trunk at the pectoral girdle. The pectoral girdle consists of two S-

shaped clavicles, or more commonly known as a collarbone, and two broad, flat, scapulae (Figure

2.3 � Anterior View of the Right Pectoral Girdle).

2.3.2.1.1 The Clavicles

�The clavicles are S-shaped bones that originate at the superior, lateral border of the manubrium of

the sternum, lateral to the jugular notch. From the roughly pyramidal sternal end, each clavicle

curves laterally and dorsally until it articulates with a process of the scapula.�

2.3.2.1.2 The Scapula

�The scapula or shoulder blade is a thin, flat triangular bone. The three sides of that triangle are the

superior border, the medial border and the lateral border. The central surface is a broad, shallow

concavity. On the superior corner is a smooth oval surface, the glenoid cavity, into which the head

of the humerus inserts.�

Figure 2.3 � Anterior View Of The Right Pectoral Girdle


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2.3.2.2 The Upper Limbs

2.3.2.2.1 The Humerus

�The humerus is the largest bone of the upper limbs. At the upper end is a hemispheric knob, called

the head. The greater and lesser tubercles, or tuberosities, are two projects lateral to the head. The

central portion of the humerus is round, but the bone becomes flattened laterally in the distal

portion. The humerus connects with the scapula with allows the humerus to rotate with three

degrees of freedom.�

�The ulna and radius are parallel bones that support the forearm. In the anatomical position, the

ulna lies medial (towards the middle of the body) to the radius.�

2.3.2.2.2 The Ulna

�The ulna is located on the medial side of the forearm. On the proximal end is a large, thick

hooklike prominence called the olecranon process. The body or shaft of the ulna is convex laterally

and dorsally. The lower end has a knobbed portion called the head beside which is a conical

projection, the styloid process.�

2.3.2.2.3 The Radius

�The radius is the lateral bone of the forearm, and lies parallel to the ulna on the thumb side of the

forearm. At the proximal end is a circular disc, the head, which articulates with the capitulum of

the humerus and ulna. The body of the radius is narrower proximally and slightly curved and

convex laterally.�

2.3.2.2.4 The Wrist and Hand

�The carpus or wrist, contains eight carpal bones. These bones form two rows: four proximal carpal

bones and four distal carpal bones. The proximal carpal bones are the scaphoid bone, lunate bone,


Anthony Hunter 13

triquetrum, and pisiform bone. The distal carpal bones are the trapezium, trapezoid bone, capitate

bone, and hamate bone. The carpal bones articulate with one another at joints that permit limited

sliding and twisting.�

�The hand is composed of five metacarpal bones that articulate from the distal carpal bones and

support the hand. Distally the metacarpal bones articulate with the proximal finger bones. Each

hand has fourteen finger bones or phalanges.�

2.3.2.3 The Pelvic Girdle �The pelvic girdle consists of two fused os coxae bones or hip bones. The pelvis is a composite

structure that includes the ossa coxae of the appendicular skeleton and the sacrum and coccyx of the

axial skeleton. The bones of the pelvic girdle must withstand the stresses involved in weight

bearing and locomotion. It is for this reason that the bones of the pelvic girdle are more massive

than those of the pectoral girdle.�

�The hipbone consists of three fused bones: ilium, ischium and pubis. At the junction of these three

bones is a deep hemispheric or cup-shaped depression called the acetabulum, which is the point of

insertion of the femoral head.� (Figure 2.4 � The Divisions of the Pelvis)

Figure 2.4 � Divisions Of The Pelvis


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2.3.2.4 The Lower Limbs

2.3.2.4.1 The Femur

�The femur is the longest, largest, heaviest and strongest of all of the skeletal bones. At the upper

end are the femoral head, neck and greater and lesser trochanters. The head is large and globular.

The neck connects the head to the body and is placed at approximately a right angle to the shaft.�

2.3.2.4.2 Tibia

�The tibia or shinbone, is the largest medial bone of the lower leg. The thickened medial and lateral

condyles of the femur articulate with the medial and lateral tibial condyles at the proximal end of

the tibia to support the weight of the body from this point upwards.�

2.3.2.4.3 Fibula

�The fibula is a slender bone on the lateral side of the leg that parallels the lateral border of the

tibia. The head articulates with the lateral condyle of the tibia just beneath the lateral ridge. The

fibula ends below in the lateral malleolus, the prominence of the outer side of the ankle.�

2.3.2.4.4 The Foot

�The foot is composed of twenty-six separate bones, divided into three main groups: tarsals,

metatarsals and phalanges. Of the tarsals, the talus is the superior bone that articulates with the tibia

and fibula. It is the second largest of the tarsal bones. Below the talus is the calcaneus, which

forms the heel. The phalanges are similar in arrangement and in number to those of the hand,

except that the shafts are round in cross section.�


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2.3.3 The Axial Skeleton

Figure 2-5 � The Axial Skeleton


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The Axial Skeleton consists of eighty bones that are divided in three groups. The Skull and

associated bones that contains twenty-nine bones, the Thoracic Cage that contains twenty-five

bones and the Vertebral Column that contains twenty-six bones (Figure 2.5 � The Axial Skeleton).

2.3.3.1 The Skull

�The bones of the skull protect the brain and guard the entrances to the digestive and respiratory

systems. The skull contains twenty-two bones: eight form the cranium, or brain case, and fourteen

are associated with the skull.�

�The cranium consists of the eight cranial bones: the occipital, parietal, frontal, temporal, sphenoid,

and the ethmoid bones. Together the cranial bones enclose the cranial cavity, a fluid filled chamber

that cushions and supports the brain.�

�The Facial bones protect and support the entrances to the digestive and respiratory tracts. The

superficial facial bones: the maxillary, lacrimal, nasal, and zygomatic bones and the mandible

provide areas for the attachment of muscles that control facial expressions and food manipulation.�

2.3.3.2 The Thoracic Cage

�The thoracic cage, or skeleton of the chest, consists of the thoracic vertebrae, the ribs, and the

sternum. The ribs and the sternum form the rib cage and support the walls of the thoracic cavity.

The thoracic cage serves two functions.

1. It protects the heart, lungs, thymus, and other structures in the thoracic cavity.

2. It serves as an attachment point for muscles involved in (1) respiration, (2) the position of the

vertebral column, and (3) movements of the pectoral girdle and upper limbs.�


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2.3.3.3 The Vertebral Column

�The rest of the axial skeleton is subdivided on the basis of vertebral structure. The adult vertebral

column, or spine, consists of twenty-six bones: the vertebrae ( twenty-four), the sacrum, and the

coccyx, or tail bone. The vertebrae provide a column of support, bearing the weight of the head,

neck, trunk and ultimately transferring the weight to the appendicular skeleton of the lower limbs.�

(Figure 2.6 � The Vertebrae Column)

�The vertebral column is divided into cervical, thoracic, lumbar, sacral, and coccygeal regions.

Seven cervical vertebrae constitute the neck and extend inferiorly to the trunk. Twelve thoracic

vertebrae form the superior portion of the back, each articulates with one or more pairs of ribs. Five

lumbar vertebrae form the inferior portion of the back, the fifth articulates with the sacrum, which

in turn articulates with the coccyx.�


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Figure 2.6 � The Vertebrae Column


Anthony Hunter 19

2.4 The Caucasian Male

A large number of studies have been preformed on human skeletons to try and devise a method of

estimating the stature of the mature person from their skeletal remains. Primarily the research was

centred on the long bones of the skeleton Forensic Anthropology [5].

From this research the Trotter and Gleser regression formulas were devised.

For Caucasian Males the Trotter Gleser regression formulas stand as

Factor Bone Difference Error +/-

3.08 Humerus 70.45 4.05

3.78 Radius 79.01 4.32

3.70 Ulna 74.05 4.32

2.38 Femur 61.41 3.27

2.52 Tibia 78.62 3.37

2.68 Fibula 71.78 3.29

1.30 Fem + Tib 63.29 2.99

Table 2.1 - Trotter Gleser Regression Formulas for a Caucasian Male

From these formulas it is possible to work backwards from a certain height to find the

corresponding lengths of the bones.

Example 2.1

If a Caucasian male were 1.75m tall then the length of the humerus would be

175 = 3.08 x humerus + 70.45 ± 4.05

Humerus = 33.94 ± 4.05

To model the humanoid robot around a human body the best method is to apply the Trotter Gleser

formulas for an average male then scale it to the required height.


Anthony Hunter 20

Bone Length cm Scaled length for 1.2m

Humerus 33.94 23.27

Radius 25.39 17.40

Ulna 27.28 18.70

Femur 47.73 32.73

Tibia 38.24 26.22

Fibia 38.51 26.41

Table 2.2- Scaled Human Lengths of Limbs for a Caucasian Male

The scaled values in Table 2.2 are ideal for the height of the humanoid robot and will be used as a

reference for the mechanical design.


Anthony Hunter 21

2.5 Human Walking

�When the human body moves there is a synchronous movement of all of the major body parts.

The pelvis lists, rotates, and undulates as it moves forward. The segments of the lower extremities

displace in all three planes of space, while the shoulders rotate and the arms sing out of phase with

the displacement of the pelvis and legs Human Walking [4].� The displacement of human limbs is

diagrammatically illustrated in Figure 2.7 - Displacement of Human Limbs During Normal Human

Walking.

�To first describe the translation of the body through space the centre of mass of the body needs to

be found. During human walking the centre of mass of the body tends to remain within the pelvis.

This is connivent as the body can be split into two portions, the upper body and lower body.�

�In normal human walking the displacement of the centre of mass describes a smooth sinusoidal

curve. The vertical displacement of a normal mans walk is about 5cm at normal speed.�

�The summits of the oscillations appear in the middle of the stance phase of the supporting limb.

The centre of mass is at its lowest level during the middle of the double weight bearing, when both

of the feet are in contact with the ground.�

�The centre of mass of a body also displaces in the horizontal direction in a normal human walk.

The displacement also describes a sinusoidal curve, with the maximum values of which pass from

right to left in association with the support of the weight bearing limb. The horizontal curve is

sinusoidal at one half the frequency of the vertical displacement.�

Figure 2.8 contains a combined plot of the sinusoidal motions for both the horizontal and vertical

displacements.


Anthony Hunter 22

Figure 2.7 � Displacement Of Human Limbs During Normal Human Walking

Figure 2.8 - Displacement Of The Centre Of Mass In Human Walking A � Lateral B � Vertical C � Perpendicular Plane of Progression


Anthony Hunter 23

2.6 Pelvic Rotation

�In normal level walking, the pelvis rotates about the vertical axis alternately to the right and to the

left, relative to the line of progression. The magnitude of this rotation is approximately four degrees

on either side of the central axis. The significance of pelvic rotation is that it flattens the arc of the

passage in compass gait such that it reduces the severity of the impact at the floor.�

Figure 2.9 - Diagram Of The Effects Of Pelvic Rotation


Anthony Hunter 24

2.7 Pelvic List

�In normal walking the pelvis lists downward in the coronal plane on the opposite side of the

weight-bearing limb. The displacement occurs at the hip joint producing an equivalent relative

adduction of the supporting limb and relative abduction of the other limb, which is the swing phase

of the cycle. At moderate speeds the alternating angular displacement is approximately five

degrees. The pelvic list contributes to the effectiveness of the abductor mechanism of the hip.�

The rotation of the human pelvis has been illustrated, therefore providing a suitable model for the

walking design of the humanoid robot. The mechanical structures of the lower extremities will be

design to resemble the pelvic list and pelvic rotation as much as possible.

Figure 2.10 - Diagram Of The Effects Of Pelvic List


Anthony Hunter 25

Chapter 3 - Design Specifications

Since the Strategic Goal of the GuRoo humanoid project is to one day compete in the RoboCup

Humanoid League, the general guidelines for the dimensions of the humanoid need to be met.

The draft of the �Definition of Humanoid� at present date ( October 19, 2001) is defined in Section

3.1 RoboCup Orgatisation [13].

3.1 Definition of Humanoid

A "Humanoid" that is eligible to participate in RoboCup Humanoid League shall meet the

following requirements:

A) The "humanoid" shall be able to walk using two legs. No wheels shall be allowed

to assist its walk.

B) The "humanoid" shall have approximate body proportion as described in Figure

3.1.

Humanoid shall be consists of two legs, two arms, one body, and one head.

Hmax is a maximum permitted height of the humanoid.

H is a height of the humanoid.

L is a length of the leg.

AS is a length of the arm measured from the shoulder.

AC is a length of the arm measured from the centre of the body.

HD is a length of the head, including a neck.

W is a weight of the humanoid.

0.4 * H < L < 0.6 * H

2 * AC < H

0.1 * H < HD

The foot of the robot shall not overlap while standing, and the surface (S) of each foot must

be S <(H/3*H/3)/2 (?)


Anthony Hunter 26

Figure 3.1 � Definition of the Humanoid Size


Anthony Hunter 27

3.2 Design Specifications

For the design of the GuRoo, the major underlying facets were to make it lightweight and easy to

manufacture in a cost effective manner. Taking these requirements into account and the fact that

the GuRoo has to be manufactured in a workshop as well as be designed and simulated on a PC, it

was preferred that the robot be built with as many commonly available components as possible.

This served two purposes. Firstly, it would give direction in a fairly uncertain design process.

Secondly, it will allow the GuRoo to be constructed from standard pieces of aluminium.

The GuRoo will have twenty-three degrees of freedom. This is intended to simulate human motion

as closely as possible without going to extremes. This also serves another purpose as it minimises

costs for the GuRoo Project.

Figure 3.2 � Diagram of the degrees of freedom

Figure 3.2 illustrates how the twenty-three degrees of freedom are designated. Two in the neck,

two in each shoulder, one in each elbow, three in the hip, three in each upper leg, one in each knee

and two in each foot.


Anthony Hunter 28

3.3 The Upper Body For the design purpose of the GuRoo functions from both the axial and appendicular human

skeleton have been combined to form the upper body.

The upper body of the GuRoo will consist of a head, a neck, a torso, two shoulders, two upper

arms, two elbows and two lower arms. This compares with the human body quite well. As stated

previously, the upper body is primarily used for balance during both the stance and swing phases of

walking. The upper body is mainly used for ascetics in the design of the GuRoo because the lower

body of the robot will weigh considerable more in comparison.

All of the components of the upper body will be made from plate alloy.

3.3.1 The Head

The head will be a suitable shape as to house the vision camera and be rigid enough to withstand the

impacts of walking to hold the camera still. It will be able to both pan and tilt as required.

3.3.2 The Neck

The neck will provide two degrees of freedom between the torso and the head. It will allow the

head to look up and down and from side to side, or pitch and yaw.

3.3.3 The Torso

The torso will be the base component of the upper body. It will hold such components as battery

packs and have motor sockets for the neck, shoulders, and lower body attachments.


Anthony Hunter 29

3.3.4 The shoulders

The shoulders will be attached to the torso and will allow for two degrees of freedom. This will

mean there will be two motors in each shoulder and various parts for connections.

3.3.5 The Upper Arm

The upper arm will be one of the components attached at the shoulder, and will be designed such

that it is able to move with two degrees of freedom without restriction.

3.3.6 The Elbow

The elbow will have one degree of freedom and will provide an attachment between the upper and

lower arms. There will be one type of motor at this joint.

3.3.7 The Lower Arm

The lower arm will extend from the elbow joint and will have a basic hand mechanism at its distal

end.


Anthony Hunter 30

3.4 The Lower Body

Like the upper body, parts from both the axial and appendicular skeleton have been combined to

form the lower body of the GuRoo.

The Lower body will consist of the spine, the waist, a hip, two leg abduction components, two leg

flexion components, two upper legs, two lower legs, two ankles and two feet. These components

will allow the GuRoo to mimic human walking quite effectively.

3.4.1 The Waist

The waist will have three degrees of freedom. This will allow the GuRoo to pitch, roll and yaw.

For this to occur there will be several parts needed to allow the three motors to achieve these

actions. The waist will attach to the torso and will also contain a spine for the GuRoo.

3.4.2 The Hip

The hip will act as a base for the GuRoo. It will provide a sturdy platform for the upper body and

allow for dynamic connections for the legs of the lower body.

3.4.3 The Leg Abduction The components that form the leg abduction will allow the leg to move away from the centre of the

body, as viewed from the anatomical position. This will be the first connection from below the hip

as the rest of the lower leg depends on this motion.

3.4.4 The Leg Flexion

The components that form the leg flexion will act to reduce the angle between two articulating

pieces. This will be the second connection from below the hip and will include such components as

bearing and motors.


Anthony Hunter 31

3.4.5 The Upper Leg

The upper leg will be one of the major structures of the leg. It will allow the rest of the lower leg to

yaw and will also provide connections for the rest of the lower leg to pitch. The PCB�s used to

control the GuRoo will be connected to the upper leg via retaining screws.

3.4.6 The Lower Leg

The lower leg will be connected to the upper leg via a motor arrangement as already described. The

lower leg will provide a link to the ankle of the GuRoo that will allow the ankle to pitch.

Additional PCB�s will be connected to the lower leg.

3.4.7 The Ankle

The Ankle is an integral part of the GuRoo design. The ankle provides a link to the foot and allows

the foot to both pitch and roll. This will require the use of two motors in a fairly compact

arrangement.

3.4.8 The Foot The foot provides a stable base for the entire GuRoo to work on. Its movement is dependent on the

ankle configuration. The foot will have some type of anti-slip device on the contact surface to

provide traction.


Anthony Hunter 32

3.5 Types of Aluminium

Following the advice of Keith Lane from the Mechanical workshop, there are two grades of

aluminium that will be considered for the construction of the GuRoo Aluminium Services & Supply

[9], the 6000 series and the 7000 series.

3.5.1 The 6000 Series 6060-T5 & 606391-T5

�The most common alloy/temper. 80-90% of all stock standard shapes are kept in this alloy. Used

for architectural purposes as it accepts paint and anodises easily.�

6351-T5 & T6

�Used for structural purposes. 6061-T6 comments apply.�

6061-T6

�High strength alloys used where extra strength is required. Surface finish is not as good as 6063

and should not be used for products that need a good clean finish. Anodising can be a problem with

this alloy.�

3.5.2 The 7000 Series 7075

�The most common alloy is now available x-stock in plate and bar. Only available in Temper 651.

This alloy finds its greatest utilisation where extreme high strength is required, especially in the

aircraft, valve, hydraulic and structural applications. It is a heat treatable alloy.�


Anthony Hunter 33

3.6 Bearings The use of bearings in the design of the GuRoo will allow its links to rotate smoothly and in some

instances take the weight of motors in the form of thrust bearings.

3.6.1 Principles of Bearing Selection and Applications

� A bearing arrangement does not only consist of rolling bearings but includes the components

associated with the bearings (shafts, housing etc.). The lubricant is also very important and in most

cases it is necessary to provide seals to prevent lubricant leakage and the penetration of

contaminants including humidity.�

�To design a rolling bearing arrangement it is necessary to select a suitable bearing type and

determine a suitable size of bearing, but that is not all. Several other aspects have to be considered:

type and quantity of lubricant, appropriate fits and bearing internal clearance, a suitable form for the

other components of the arrangement, adequate seals etc. Each individual decision influences the

performance, reliability and economy of the bearing arrangement.�


Anthony Hunter 34

Figure 3.3 � Bearing Types

Some bearings that are of particular interest to the design of the humanoid are the deep groove ball

bearings and the single direction thrust bearings.

The deep groove ball bearings are suitable for the GuRoo design because they are able to carry axial

loads in both directions in addition to radial loads at high speeds. This makes it ideal for the foot.

Single direction thrust ball bearings are suitable for configurations that place axial loads on the

bearings. This makes this type of bearing suitable for applications with a yaw component.


Anthony Hunter 35

3.6.1.1 Deep groove ball bearings

�Deep groove ball bearings are particularly versatile. They are simple in design, non-separable,

suitable for high and even very high speeds and are robust in operation, requiring little maintenance.

Because of these properties and a favourable price, they are the most widely used bearing type.

Consequently, they are available in many designs and sizes.�

3.6.1.2 Single direction thrust ball bearings

�SKF single direction thrust ball bearings comprise a shaft washer, a housing washer and a ball and

cage thrust assembly. The bearings are separable so that mounting is simple as the washers and ball

and cage assembly can be mounted separately.�

�The smaller sizes are available with either a flat seating surface on the housing washer or a sphered

seating surface. The bearings with sphered housing washer can be used together with a sphered

support washer to compensate for errors of alignment between the support surface in the housing

and the shaft. The sphered support washers are also supplied by SKF but they must be ordered

separately.�

�Single direction thrust ball bearings, as the name suggests, can accommodate axial loads in one

direction and thus locate a shaft axially in one direction. They must not be subjected to radial load.�

3.7 Bosses

Bosses are used to connect motor and gearbox shafts to mechanical structures. This is achieved by

screwing a grub screw perpendicularly into the side of the motor shaft. This provides a force

against the shaft that locks the shaft into place and subsequently forms a connection to a mechanical

structure.


Anthony Hunter 36

Chapter 4 � GuRoo Implementation

The actual design of the GuRoo was a long and time-consuming process with many alterations

required along the path of creation. It is for this reason that there were multiple team members

working on this aspect of the GuRoo. These members included Mark Wagstaff [15] and Damien

Kee [6]. Mark Wagstaff worked as the chief Mechanical Engineer on the GuRoo project, working

on and having the final say on all designs.

4.1 The Upper Body The upper body consists of the head, neck, shoulders, arms and the torso. As stated previously, the

upper body is primarily used for balance during both the stance and swing phases of walking. As

the GuRoo is trying to simulate normal human walking as much as possible, the upper body will be

used for balance during each phase of the walking cycle. Within the actual simulation the limbs of

the upper body do not have a great impact on the balance of the GuRoo Andrew Smith [8]. This is

due to the current walking algorithm being static at the present date.


Anthony Hunter 37

4.1.1 The Head

The head is primarily used to house the Omnivision 7620 CMOS Digital Camera that is used for the

vision system. Within the folded head there is a plate that is used to mount the Omnivision camera.

This plate, and the head, has been situated so that the camera can be mounted in such a position that

it is able to see an object clearly without interference from other objects. The head has been

designed so that it can yaw and pitch.

The head is made from 6061-T6 series 3.125mm thick aluminium that has been specifically chosen

so that it can be folded, as the shape of the head requires (See Figure 4.1 � The Head and Neck

Assembly).

The full specifications of the head can be found in Andrew Blower [16].

Figure 4.1 � The Head and Neck Assembly


Anthony Hunter 38

4.1.2 The Neck

The neck supports the head and camera configuration. The neck is composed of two pieces, the

neckpiece and a HS705 bracket. These two pieces allow the head to both pan and tilt. These pieces

are able to move due to the two Hi-Tech HS705 servomotors that are connected by M4 Unbrako

screws to these pieces.

When designing the neck it was necessary to consider such factors as sturdy support for the head

and camera, which need to have a stable platform for viewing objects. The best method that was

devised was to create a design that secured the head with Unbrako screws. This meant that the non-

uniformly distributed weight of the head could be held stable when being tilted.

4.1.3 The Torso

The torso is a vital part of the humanoid design. It needs to be able to hold all four of the battery

packs, Vision, IPAC and Power boards within the thoracic cage or the chest cavity as well as

provide a stable structure for the shoulders, arms, head and neck to operate off. It is for these

reasons that the torso was designed with the basic similar shape of a male human�s chest. This

means that the lower portion of the torso is fairly narrow and it becomes wider towards the base of

the shoulder region. This is highly accentuated but for the GuRoo design is works quite well.

The torso also contains HS705 motor socket in each of the shoulder that allow for a dynamic

connection between the torso and each of the shoulders and arms.

The battery packs are housed within the chest cavity along the rib section, analogous of a human

man and also on an internal shelf that resides around the level of the shoulders (See Figure 4.2 �

The Torso Assembly).


Anthony Hunter 39

Figure 4.2 � The Torso Assembly

4.1.4 The Shoulders

The shoulder configuration is connected to the torso via a HS705 Servo Motor. This motor allows

the arm configuration attached to pitch relative to the frontal plane Appendix G.


Anthony Hunter 40

Figure 4.3 � The Shoulder Hi-Tech Servo Motor Connection

The shoulder configuration is a relatively simple configuration containing three different parts. The

parts of the shoulder are the shoulder bracket, a HS705 servomotor and an 8mm flanged radial

bearing.

The actual shoulder part has two vertically disposed flanges (See Figure 4.4 � The Shoulder

Assembly) that allow for a connection to the upper arm (See Figure 4.5 � The Elbow and Arm

Assembly). This allows the arm to roll with respect to the frontal plane. The arms roll abilities is

limited by a limit plate, (See Figure 4.3 � The Shoulder Hi-Tech Servo Motor Connection), which

limits the roll to a horizontal position.


Anthony Hunter 41

Figure 4.4 � The Shoulder Assembly

Through the shoulder motor hole, a Hi-Tech HS705 servomotor is attached to the Arm Upper piece.

On one side of the upper arm is a hole that allows the top of the servomotor to be attached as

previously state. On the other side of the upper arm is a series of holes displaced ninety degrees

apart that allow for that side to be pinned onto the shoulder via a 20mm pin and an 8mm flanged

radial bearing thrust bearing Appendix D (DDR-830).


Anthony Hunter 42

4.1.5 The Elbow

The elbow joint is composed of five pieces, the Lower Arm, the Upper Arm, HS705 servomotor,

HS705 motor bracket, 20mm pin and 8mm flanged bearing. The elbow joint allows the Lower Arm

to pitch in the frontal plane when the rest of the Upper Arm and Shoulder configuration is in its

starting position. Its configuration is similar to that of the shoulder assembly, as it basically

performs the same function.

Figure 4.5 The Elbow and Arm Assembly


Anthony Hunter 43

4.2 The Lower Body

The Lower body will consist of the spine, the waist, a hip, two leg abduction components, two leg

flexion components, two upper legs, two lower legs, two ankles and two feet. These components

allow for a practical simulation of human walking that incorporates the movements that have been

discussed in Chapter 2.5.

4.2.1 The Waist and Spine

The waist and spine assembly of the GuRoo has three degrees of freedom, being pitch, roll and yaw.

This enables GuRoo to bend over, tilt from side to side and swivel with respect to the frontal plane.

This spinal configuration is obviously far less complex that that of a human�s vertebrae column but

still provides enough range of movement to allow the GuRoo to mimic the basic human motions of

the spine.

Figure 4.6 The Waist and Spine Assembly


Anthony Hunter 44

4.2.1.1 Pitch

The base level of the waist is the pitch assembly. The motor used to pitch the GuRoo is attached to

the Hip via a vertical flange on the hip that connects the hip to the waist via a 12mm boss assembly.

This locks the motor into place and also provides a firm dynamic connection between the hip

assembly and the pitch assembly.

The other side of the hip connection to the pitch assembly is connected through the hip bracket.

The hip bracket was needed because it made the mounting of the pitch motor possible due to size

restrictions. This hip bracket is fixed to the pitch assembly via a 14mm pin and an 8mm flanged

bearing and will be attached to the Hip via 4mm rivets. This ensures that the pitch assembly can

pitch freely and smoothly and also allows for an easy assembly process (See Figure 4.7 � The Pitch

Assembly).

Figure 4.7 - The Pitch Assembly


Anthony Hunter 45

4.2.1.2 Roll

The middle level of waist is the roll assembly. The waist 1 part that provided the attachment for the

pitch motor provides the base for the roll of the GuRoo. The flanges for the roll motor are

oppositely opposed from the pitch flanges. The waist 1 part is connected to the waist 2 part in the

same fashion as the waist 1 part is attached to the hip, eg with a 14mm pin and a 8mm bearing on

one side and a boss and motor on the other.

Figure 4.8 - The Pitch � Roll Assembly


Anthony Hunter 46

4.2.1.3 Yaw

The top level of the spine waist assembly is the yaw assembly Figure 4.5. The yaw assembly is

attached to the roll assembly in the same fashion as the roll assembly is attached to the pitch

assembly via a 14mm pin and an 8mm flanged bearing. The spine consists of three 7075 aluminium

rods displaced by 120o. The end of the spinal shaft contained within the yaw assembly is attached

to the torso via a weld on hub that attaches to the motor shaft. A 65mm-thrust bearing provides the

smoothness found within the yawing motion and is located using a spigot (See Figure 4.9 � The

Yaw Assembly Attached to the Torso).

Figure 4.9 � The Yaw Assembly Attachment to the Torso


Anthony Hunter 47

4.2.2 The Hip The hip assembly contains the motor arrangement for the first degree of freedom of the upper leg.

As a component it provides the base for the three degrees of freedom for the spine of the robot, and

a point to mount the controller boards for the GuRoo (See Figure 4.10 � The Under Side of the

Hip). As a design feature the first degree of freedom of the hip contains two torsion springs. These

torsion spring add an extra 1Nm per degree, Damien Kee [6], which provides resistance to

abduction and adduction to the legs of the GuRoo.

Figure 4.10 � The Under Side of The Hip


Anthony Hunter 48

4.2.3 Upper Leg Abduction

The abduction link provides the second degree of freedom of the hip assembly (See Figure 4.11 �

The Leg Abduction). The joint for abduction of the upper legs takes place 75mm away from the

centre of the hip. This restricts the GuRoo�s ability to abduct and adduct as previously stated. The

motor of the abduction assembly provides the link to flexion assembly.

Figure 4.11 � The Leg Abduction


Anthony Hunter 49

4.2.4 The Leg Flexion

This assembly contains no actuation (See Figure 4.12 � The Flexion Assembly). This links purpose

is to provide a mechanical link to the rest of the lower leg via a taper lock bush and weld on hub

arrangement. Basically the bush is mated with motor assembly from the upper leg assembly and

placed within the weld on hub. When the bush is set within the weld on hub it is locked via a series

on angled screws that cause the hub to squeeze the bush.

Figure 4.12 � The Flexion Assembly


Anthony Hunter 50

4.2.5 The Upper Leg

The upper leg allows the rest of the lower leg to rotate (See Figure 4.13 � The Upper Leg

Assembly). The upper leg assembly is composed of seven pieces: the inner bracket, the outer

bracket, the spigot for the 65mm thrust bearing, the thrust bearing, two motor assemblies and a PCB

mounting panel. This configuration creates a boxing link around the PCB that saves it from damage

from impacts by securely mounting the Controller PCB to the PCB mounting panel via a series of

four Unbrako flat head socket screws.

The vertical motor assembly, that provides the taw for the upper leg, contains the gearbox that

connects to the flexion assembly.

Figure 4.13 � The Upper Leg Rotation Assembly


Anthony Hunter 51

4.2.6 The Lower Leg

The lower leg assembly has much the same configuration as the upper leg assembly, with the same

basic components: the inner bracket, the outer bracket, a boss and 14mm pin arrangement, a motor

assembly, a cross piece and a PCB mounting panel.

This motor assembly provides the pitch actuation for the ankle joint. This assembly is the first

assembly to be manufactured as described in Chapter 6.

Figure 4.14 - The Lower Leg Assembly


Anthony Hunter 52

4.2.7 The Ankle The ankle is an integral part of the GuRoo design that provides one degree of freedom in the ankle

(See Figure 4.15 � The Ankle). It was a source of much difficulty as it bears the full load of the rest

of the upper body.

The ankle consists of three parts: the ankle itself, the ankle bracket and the ankle shaft. These

pieces have been designed to allow the roll motor assembly to be mounted along the shaft of the

foot.

Figure 4.15 - The Ankle


Anthony Hunter 53

4.2.8 The Foot

The foot is a highly underdeveloped part of the GuRoo, with the original design specifications in

Chapter 3.4.8 not being met. The foot as it is has a flat 6061-T6 aluminium surface that will need

closer inspection when it comes time for manufacture (See Figure 4.16 � The Foot Assembly). The

foot assembly contains four pieces at present: the foot, the boss assembly, the ankle shaft support

bracket and a radial bearing.

When the foot is redesigned it will contain sensors, and other associated feature to smooth the

GuRoo�s gait pattern.

Figure 4.16 � The Foot Assembly


Anthony Hunter 54

4.3 Common Parts

There are a series of generic parts that were needed within various assemblies. These parts included

spigots for thrust bearings, bosses for connections between the Maxon RE-36 motor, Planetary

Gearhead GP 42 and HEDS 55 Digital Encoder to various parts.

4.3.1 Bosses

As already discussed, bosses are used to attach mechanical parts to the gearbox � motor

configuration. This allows the links to move due to the torque that is transmitted through the

gearhead. The boss has a 12mm shaft to allow a snug fit between itself and the gearhead. This

shaft also contains an A4 x 4 x 20 keyway that provides a point for the gearhead to grip the shaft

when turning. The boss connects to various links via an end cap and two M3 button head screws

Appendix E.

Figure 4.17 � The Boss Assembly


Anthony Hunter 55

4.3.2 The Motor Assembly

DC motors actuate all of the actuated links in the lower body. The motor assembly consists of three

components. The Maxon Re-36 DC Motor, the Planetary Gearhead GP 42 with a four stage 156:1

ratio and a HEDS 55 Digital Encoder. The motor selection was carried out by Damien Kee [6], and

the data sheets of his motor assembly components are contained in Appendix H. (See Figure 4.18 �

The Motor Assembly).

Figure 4.18 � The Motor Assembly


Anthony Hunter 56

4.3.3 Spigot

To hold the three 65mm thrust bearings in place for the vertical motor assemblies, namely in the

yaw of the spine and the two of the upper leg rotation (See Figure 4.6 and Figure 4.13), a guide was

needed to stop the bearing from slipping off the mounts. This came in the form of a spigot, which

is a circular piece of material with a lip on its edge for guidance. The spigot has a shaft hole so that

the gearhead�s shaft can be connected with a taper lock bush arrangement.

Figure 4.19 � Spigot for Thrust Bearing Locating


Anthony Hunter 57

Chapter 5 - Software Implementation

Once the parts have been have been designed in Solid Edge, it is necessary to find the equations of

motion for rigid bodies so that the kinetics of rigid bodies in three dimensions can be found. This

process was used to model the GuRoo so that it can be simulated for walking in the program called

Solid Works.

To understand how the GuRoo is modelled in Solid Works, there is some background information

that is necessary to comprehend Beer and Johnson [7].

5.1 Equations of Motion for a Rigid Body Consider a rigid body acted upon by several external force F1, F2, F3, etc.

Figure 5.1 - Rigid Body Acted Upon By Several External Forces

�If we first consider the motion of the mass centre G of the body in Figure 5.1 with respect to the

newtonian frame of reference Oxyz, we can write the fundamental equation, Equation 5.1.�

ΣF = m ã Equation 5.1

�Where m is the mass of the body and ã the acceleration of the mass centre G.

The motion of the body relative to the centroidal frame of reference Gx�y�z� can now be

determined, Equation 5.2.�

ΣMG = ĤG Equation 5.2


Anthony Hunter 58

�Where ĤG represents the rate of change of HG, the angular momentum about G of the system of

particles forming the rigid body.�

Equations 5.1 and 5.2 apply in the most general case of the motion of a rigid body.

5.2 Angular Momentum of a Rigid Body in Plane Motion

�Consider a rigid slab in plane motion. Assuming that the slab is made of a large number n of

particles Pi of mass ∆mi, we note that the angular momentum HG of the slab about its mass centre G

may be computed by taking the moments about G of the momenta of the particles of the slab in

their motion. This gives the angular momentum equation below.�

HG = ∑=

n

i 1(r�i x v�i mi) Equation 5.3

�Where r�i and v�∆mi denote, respectively, the position vector and the linear momentum of the

particle PI relative to the centroidal frame of reference Gx�y�.�

�Since the particles of this Equation 5.3 belong to the slab, we have v�i = ω x r�i, where ω is the

angular velocity of the slab at the instant considered. We write now have the equation.�

HG = ∑=

n

i 1(r�i x (ω x r�I) ∆ mi) Equation 5.4

�Recalling that the sum Σr�i2∆mi represents the moments of inertia I of the slab about the centroidal

axis perpendicular to the slab, it can be concluded that the angular momentum HG of the slab about

its mass centre is defined by Equation 5.5.�

HG = I ω Equation 5.5


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5.3 Angular Momentum of a Rigid Body in Three Dimensions. �At present the angular momentum HG of a body in plane motion can be found. Now we can see

how the angular momentum HG of the body about its mass centre G may be determined from the

angular velocity of the body in the case of three-dimensional motion.�

According to Section 5.2, Equation 5.3, we can use this equation for determining components of a

vector product.

Through some maths manipulation we can obtain the components of angular momentum HG of the

body about its mass centre.

HX = +Îxx ωx - Îxy ωy - Îxz ωz

Hy = -Îyx ωx + Îyy ωy - Îyz ωz Equation 5.6

HZ = +Îzx ωx - Îzy ωy + Îzz ωz

�These relations in Equation 5.6 show the operation that transforms the vector w into the vector HG

as illustrated in Figure 5.3 is characterised by the array of moments and products of inertia in

Equation 5.7.�

Îxx - Îxy - Îxz

I = -Îyx Îyy - Îyz Equation 5.7

-Îzx - Îzy Îzz

This array defines the inertia tensor of the body at its mass centre.


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5.4 Retrieving Data from Solid Edge for Inertia Tensors Once the parts have been designed in Solid Edge it was necessary to find the inertia tensors so the

GuRoo could be simulated by Andrew Smith [8] in Solid Works. For this to happen it was

necessary to designate the densities of the pieces of metal that was being used.

As the GuRoo was being made from 6061T6 grade Plate Alloy and tempered 7075 T651 grade

alloy Aluminium Services & Supply [9] [Appendix C], and the bearings were made from different

grades of steel SKF General Catalogue [10], a general density chart was created.

Material Purpose Density

(kg/m) Aluminium body parts 2700Steel Bearings 7700Steel Screws 7500

Table 5.1 - Densities of Materials Used The according densities were inserted into Physical Properties of various parts and from this the

inertia tensors were calculated. Theses values were then used to generate a file containing the DM

properties of parts, Damien Kee [6], which was inturn used to simulate the walking of the GuRoo,

Andew Smith [8].


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Chapter 6 - Product Evaluation

The design specifications of Chapter 3 are in the process of being met in a physical sense with the

manufacturing process in progress. The GuRoo has been totally designed using Solid Edge,

specifying every part and joint that was discussed in Chapter 3.

At this stage you should be familiar with how the GuRoo has been planned and designed in Solid

Edge. The Solid Edge drafts Mark Wagstaff [G] have been sent to the University of Queensland

Electrical Mechanical workshop to be manufactured by staffs that includes Keith Lane and Bill

Slack.

As of Wednesday October 17, the parts of the GuRoo that have been manufactured are two lower

legs and the bosses used to connect the motors to the various pieces.

Figure 6.1 � Boss, Motor, Lower Leg Setup


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6.1 Design Process of Lower Leg

From the standard plate 6061T6 3.125 mm Alloy that was ordered the lower leg panels were cut

using the Guillotine into the general shape described by the Solid Edge Drafts, taking note of the

lower legs part.

Figure 6.2 � The Guillotine

Once the pieces have been cut using the Guillotine the centre of the milled holes were marked using

a centre punch. From here the holes were cut undersized using a holesaw. The holes were cut

undersized so that the exact hole dimensions could be cut into aluminium using the milling

machine.

The Lower Leg Panel was then set in the vice on the milling machine and using the digital readout

on the Milling Machine, the exact hole size was cut using a boring head.


Anthony Hunter 63

Figure 6.3 � The Exact Hole Being Cut On The Using A Boring Head On The Milling

Machine

Various other tools were used to create other holes into the lower leg pieces using the milling

machine.

For the motor connections on each piece, Bill thought that it would be easier to create a template

block to create the holes than to create each every individual set of holes. This template was

aligned on the Milling Machine and the holes were created using various drill pieces.

Scribing around a template that Bill manufactured produced the rounded ends of the Lower leg

panels.

Other parts of the humanoid will be manufactured using these techniques and machines and many

other processes.

The parts of the lower leg are held together using 4mm pop rivets, which form a very tight fit

between pieces.


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6.2 Design of the 12mm Boss As previously discussed the 12mm bosses are used to attach the motor assembly to various pieces

around the body. For this to occur a 12mm hole needs to be drill out of the Round Structural bar

that will form the gearhead attachment for the motors. This hole was produced using spiral fluted

machine reamer.

The keyway was created using a mechanical press with the guide piece inserted into the 12mm hole

and the broach connected to the press.

Figure 6.4 � Broach Set: Guide, Broach and Depth Pin

For the screw holes that are created on the top of the boss a PVC template block was created to use

a guide to drill the holes on the boss on the milling machine.

To create the grub screw screw-hole, two pegs were placed under the round section of the boss to

hole it secure. This allowed the drill to create a linear hole without damage to the milling machine

or the boss.


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Figure 6-5 The 12mm Boss


Anthony Hunter 66

6.3 How Well I performed

As I�m an Electrical Engineer studying for a Mechatronics Minor, I have a limited amount of

knowledge of mechanical structures and the processes used for the linking of parts. From my

Mechatronics minor I have gained experience in the use of Solid Edge, and also some low level

Robotics using Lego Technic pieces to create objects such as robot arms and line following robots.

The main method that I used to deal with my lack of experience was to ask as many questions as

possible from people with experience in the field of robotics. This included people from workshops

and others such as Tony Schmidt from SKF Bearings.

Other skills that I have developed to work on this project were a refresh of the theory behind the

mechanical formulas and methods used to create parts. This included areas such as inertia tensors,

Beer and Johnson [7]. Another important skill that I have gained is an introduction into the human

skeletal system and how joints and limbs move during walking.


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Chapter 7 � Future Developments

7.1 Implementation of GuRoo Version 2.0

At this point of time Version 1.0 of the GuRoo has been designed in Solid Edge and is being

manufactured in the workshop. If I had to design Version 2.0 of the GuRoo I would spend more

time in the research phase of production. By this I mean take more time researching how other

Universities from around the world have gone about designing relatively low cost humanoid robots.

This means researching how others have linked joints with motors and the types of configurations

they have used to do so.

In the planning stage I would spend more time with the people manufacturing the GuRoo to find out

more about the processes used in manufacturing. For example I assumed that the GuRoo would be

welded but if I conferred with Bill Slack in the workshop I would have found out that welding

aluminium would cause some loss in the size of pieces. It is for this reason that rivets are being

used for fixing pieces together as this is much simpler to implement and a lot less time consuming.

A major area that needs attention in the GuRoo design was the foot. There are many options that

could be considered when designing the foot. These include prosthetics and rubber solutions. These

would provide a more suitable kicking mechanism than an aluminium frame when it comes to the

RoboCup Humanoid League Competition.

7.2 Conclusion

In conclusion the Strategic Goal of the team of creating a three dimensional humanoid robot that is

capable of standing freely and walking is well on track with the design of Version 1.0 of the GuRoo

being completed in Solid Edge. There is still progress to be made in all areas of the GuRoo

humanoid design, with the intelligence aspect still requiring some work and testing as a complete

unit. It is foreseeable that in future years the GuRoo will walk and compete successfully in a

Humanoid Robot Competition.


Anthony Hunter 1

APPENDIX A

Bibliography

[1] The Honda Humanoid Robot, �Humanoid Robot Site�, www.honda.co.jp/tech/others/index.html (current Oct. 16 2001) [2] S. Horn, Thecondont � The Biped Walker, Undergraduate Thesis, University of Queensland, 1999 [3] F.H. Martini, Fundamentals of Anatomy & Physiology, Prentice Hall International INC, Upper Saddle River, New Jersey, 1998

[4] V.T. Inman, H.S. Ralston and F. Todd, Human Walking, William and Wilkins, Baltimore, 1981

[5] M.Y. El-Najjar, K.R McWilliams, Forensic Anthropology, Charles C Thomas, 1978

[6] D. Kee, Drive System Selection and Simulation for a Humanoid, Undergraduate Thesis,

University of Queensland, 2001

[7] F.P. Beer and E.R Johnson, Vector Mechanics for Engineers, McGraw-Hillm Singapore, 1990

[8] A. Smith, Simulator Adaption and Gait Pattern Creation for a Humanoid Robot, Undergraduate

Thesis, University of Queensland, 2001

[9] Aluminium Services and Supply, �Aluminium Rolled and Extruded Products�,

www.aluminiumservices.com.au, (current Oct 19, 2001)

[10] The SKF Group, �SKF Group Homepage�, http://www.skf.com (Current Oct 19, 2001)

[11] Maxon Motors, �DC + EC Motors Gearheads Controllers and Acessories�,

http://maxonmotorusa.com/ (current Oct. 16, 2001)

[12] NMB Corporation, �NMB Minature Bearings�,

http://www.nmbcorp.com/html/minicatalog.html (current Oct 16, 2001)


Anthony Hunter 2

[13] RoboCup Organisation, �RoboCup Humanoid League 2002 Rule�

http://www.robocup.org/regulations/humanoid/rule_humanoid.htm (current Oct 16, 2001)

[14] SPS Technologies, �Unbrako Product Division�, www.spst.com/unbrako.html (Current Oct 16, 2001)

[15] M. Wagstaff, Mechanical Design for a Humanoid Robot, Undergraduate Thesis, University of

Queensland, 2001

[16] A. Blower, Development of a Vision System for a Humanoid Robot, Undergraduate Thesis,

University of Queensland, 2001

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