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Ironman Project - Design Of Electro-Mechanical Muscle For Elbow Exoskeleton Robot

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I

“I hereby declare that I have read through this report entitle “Ironman project - Design of electro-mechanical muscle for elbow exoskeleton robot” and found out that it has comply the partial fulfillment for awarding the degree of Bachelor of

Mechatronics Engineering”

Signature : ...

Supervisor’s Name : Encik Nur Latif Azyze Bin Mohd Shaari Azyze

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IRONMAN PROJECT - DESIGN OF ELECTRO-MECHANICAL MUSCLE FOR ELBOW EXOSKELETON ROBOT

LIM CHEE AN

A report submitted in partial fulfillment of the requirements for the degree Of Bachelor of Mechatronic Engineering

Faculty of Electrical Engineering

UNIVERSITI TEKNIKAL MALAYSIA MELAKA

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I declare that this report entitle “Ironman project - Design of electro-mechanical muscle for elbow exoskeleton robot” is the result of my own research except as citied in the reference. The report has not been accepted for any degree and is not

concurrently submitted in candidature of any other degree.

Signature : ...

Name : Lim Chee An

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ACKNOWLEDGEMENT

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ABSTRACT

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ABSTRAK

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VII

TABLE OF CONTENT

TITLE PAGE

ACKNOWLEDGEMENT ... IV ABSTRACT ... V ABSTRAK ... VI TABLE OF CONTENT ... VII LIST OF TABLE ... IX LIST OF FIGURE ... X

CHAPTER 1 ... 1

INTRODUCTION ... 1

1.1 Background ... 1

1.2 Problem statement ... 2

1.3 Objective of Project ... 2

1.4 Scope of Project ... 3

CHAPTER 2 ... 4

THEORY AND LITERATURE REVIEW ... 4

2.1 Introduction ... 4

2.1.1 Exoskeleton robot ... 5

2.1.2 Elbow complex ... 5

2.1.3 Classification of Upper-Limb Exoskeleton Robots ... 6

2.1.4 Actuation System ... 7

2.1.5 Power Transmission System ... 8

2.1.6 Speed Control by Using PWM ... 8

2.1.7 Speed Control by Full H Bridge Motor Driver ... 10

2.1.8 Speed Control by using MOSFET and delay ... 10

2.2 Theory ... 11

2.2.1 Hardware ... 11

2.2.1.1 Microcontroller ... 12

2.2.1.2 PIC microcontroller start-up kit ... 12

2.2.1.3 DC Motor ... 13

2.2.1.4 Gyro meter sensor ... 15

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VIII

2.2.2.1 MikroC ... 17

2.2.2.2 Proteus ... 17

2.2.2.3 Arduino Software ... 18

2.2.2.4 Solid Works ... 19

CHAPTER 3 ... 20

METHODOLOGY ... 20

3.1 Introduction ... 20

3.2 Flowchart of project... 21

3.3 Literature Review / Technical Research ... 23

3.3.1 Hardware ... 23

3.3.1.1 Designing Electronics Circuit ... 23

3.3.1.2 PIC Microcontroller ... 24

3.3.1.3 Gyro sensor ... 24

3.3.1.4 Power Supply Circuit ... 26

3.3.1.5 DC Motor Driver ... 27

3.3.1.6 Relay ... 28

3.3.1.7 DC motor ... 29

3.3.1.8 Loading Unit (weight plate 1kg &2kg) ... 30

3.3.2 Software ... 31

3.3.2.1 MikroC and Proteus ... 31

3.3.2.2 Sensor position setup ... 34

3.3.2.3 Solid Works ... 36

CHAPTER 4 ... 38

RESULT ... 38

4.1 Introduction ... 38

4.2 Hardware Result ... 38

4.3 Experiment: Determine Relationship of angular rate and angle of movement ... 39

4.3.1 Experiment 1: Payload Experiment which using human arm ... 39

4.3.2 Experiment 2: Payload Experiment which elbow arm lever actuated by dc motor ... 41

CHAPTER 5 ... 49

ANALYSIS AND DISCUSSION OF RESULT ... 49

5.1 Introduction ... 49

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5.2 Discussion ... 54

CHAPTER 6 ... 56

CONCLUSION AND RECOMMENDATION ... 56

6.1 Conclusion ... 56

6.2 Recommendation ... 57

REFERENCES ... 58

APPENDIX ... 60

LIST OF TABLE TABLE PAGE Table 3.1 Pin connection of PIC16F877A for DC motor speed control system ... 24

Table 3.2: Logic function of motor driver ... 28

Table 3.3: Performance of motor (WD21100) ... 30

Table 3.4: direction control of DC motor ... 33

Table 3.5: Result for DC motor speed controlling ... 34

Table 4.1: Angle of Movement, θ (°) versus Angular velocity of lower arm (elbow joint), , (rad/sec) ... 41

Table 4.2: Angle of Movement, θ (°) versus Angular velocity of lower arm (elbow joint), , (rad/sec) for each motor speed condition - Without load ... 43

Table 4.3: Angle of Movement, θ (°) versus Angular velocity of lower arm (elbow joint), , (rad/sec) for each motor speed condition - With load (1kg weight plate) ... 44

Table 4.4: Angle of Movement, θ (°) versus Angular velocity of lower arm (elbow joint), , (rad/sec) for each motor speed condition - With load (2kg weight plate) ... 45

Table 4.5: Aaverage of Angular velocity, , (rad/sec), Force, F (N), Torque, T (Nm) for each angle of human hand elbow joint movement ... 47

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LIST OF FIGURE

FIGURE PAGE

Figure 2.1: Human Upper Limb Motion Assist Exoskeleton Robots. [2] ... 5

Figure 2.2: Elbow complex and elbow motions. (a) Elbow anatomy. (b) Elbow flexion/extension motion. (c) Forearm supination/pronation motion. [3] ... 6

Figure 2.5 Joint axis drive system. [5] ... 8

Figure 2.6: PWM (Pulse Width Modulation) [5] ... 9

Figure 2.7: Relation of supply voltage with motor speed [5] ... 9

Figure 2.8: Full H bridge motor drive [5] ... 10

Figure 2.9: A power-switching element (bipolar transistor, MOSFET) used to vary speed of motor. [5] ... 10

Figure 2.10: wiring diagram of delay [5] ... 11

Figure 2.11 Variety of microcontrollers available in the market ... 12

Figure 2.12: SK40C Start-up Kit ... 13

Figure 2.13: Construction of DC motor. [5] ... 13

Figure 2.14: Relationship between motor speed and torque for a DC motor. [5] ... 14

Figure 2.15: Effect of changing the applied voltage. [5] ... 14

Figure 2.16: Relationship among speed, torque, and output power. (a) Low speed. (b) Moderate speed. (c) High speed. [5]... 14

Figure 2.17 Joint axis drive system. [5] ... 15

Figure 2.18: Gyroscope Model [13] ... 15

Figure 2.19: (a) Top view of pin diagram and (b) axis definition of gyro sensor (ITG-3200) [13] ... 16

Figure 2.20: MikroC program window ... 17

Figure 2.21 Proteus program windows ... 18

Figure 2.22: Arduino Programming IDE ... 18

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Figure 3.1: Methodology Flowchart ... 21

Figure 3.2: K-Chart ... 22

Figure 3.3 Block diagram of DC motor speed control system ... 22

Figure 3.4: Integration of Circuit Board ... 23

Figure 3.5: PIC16F84A IC Pin Diagram ... 24

Figure 3.6: Arduino UNO top view [13] ... 25

Figure 3.7: Schematic of Arduino and Sensor Board Connection [13] ... 25

Figure 3.7 IC LM7805 ... 26

Figure 3.8 Schematic circuit of +5V power supply ... 26

Figure 3.10 DC motor operational controls [5] ... 28

Figure 3.11: Motor (WD21100) chosen for this project [12] ... 29

Figure 3.12: Mechanical data sheet of motor (WD21100) [12] ... 30

Figure 3.13: 1kg & 2kg weight plate [9] ... 30

Figure 3.14: Schematic of overall project ... 31

Figure 3.15 PWM output ... 32

Figure 3.16: Converting a PWM signal to DC motor voltage input: (a) Maximum forward speed, (b) 75% forward speed, (c) 50 % forward speed, (d) 20% reverse speed. ... 34

Figure 3.17: Sensor placing position on arm ... 35

Figure 3.18: block diagram of experimental setup ... 35

Figure 3.19: Flowchart for program gyro ... 35

Figure 3.20: Data send and display on PC... 36

Figure 3.21: Four view viewport with 3rd angle projection of elbow arm for experimental purpose ... 37

Figure 4.1: Hardware parts ... 38

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Figure 4.3: Electro-mechanical elbow orthotics ... 42 Figure 4.4: Position of elbow Arm Movement of Lower Arm (Elbow Joint) ... 42 Figure 5.1: Tri-axial angular rate for different load at each angle of movement ... 49 Figure 5.2: The definitions of the gyro sensor attach on reference frame. The unit y-axis is defined along the segment, upwards, the z-axis point in dorsal direction and the x-axis laterally. ... 50 Figure 5.3: Tri-axial gyroscope raw data for different load which assist using dc motor. .. 51 Figure 5.4: Result of Average of angular velocity, force, and torque for each angle of elbow movement ... 52 Figure 5.5: Result of Average of angular velocity, force, and torque for each angle of elbow movement ... 53

LIST OF APPENDICES

TITLE PAGE

Appendix A - 3D view of a 1 DOF prototype upper arm (elbow joint)

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CHAPTER 1

INTRODUCTION

1.1 Background

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estimation. Gyroscopes measure angular velocity, which can be used to estimate a change in orientation.

1.2 Problem statement

1. Complicated and hard to use by patient/aged people for existing mechanism of elbow rehabilitation exoskeleton.

2. Expensive cost in mechanical structure of elbow joint actuator for weight training. 3. Complexity of comparison method of kinematic and dynamic data for elbow

movement in active mode and passive mode.

1.3 Objective of Project

Basically, these projects are listing three main objectives. The objectives are a guideline and goal in order to complete this project. This project is conducted to achieve the following objectives:

1. Design and fabricates a low complexity and low engineering and construction cost of a 1 DOF motion prototype upper arm(elbow joint) training/rehabilitation (exoskeleton) system

2. To design a dc motor system for electro-mechanical structure of elbow joint

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1.4 Scope of Project

In order to achieve the objective of the project, there are several scope had been outlined. There are two scopes in this project which is hardware development and software development.

For the first scope which is hardware development are three main sections and those section are:

1. Design and fabricate an actuation system for elbow which using dc motor as experimental purpose.

2. Design a speed control DC motor circuit using PIC Microcontroller

For the second scope which is the software development, there are two main sections and that section are:

1. To simulate the dc motor control system using Proteus software.

2. Program and communicate with an Arduino board to collect measurement data from gyro sensor.

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CHAPTER 2

THEORY AND LITERATURE REVIEW

2.1 Introduction

This chapter introduces and explains the source of idea for design, concept, specification and other information that related to the project. It is found base on the product that have been develop or research by institutions before this project and some of them may be available in market nowadays. This study should be done to ensure that project is being developed to run efficiently while achieving the desired objective. All the theories of all devices and compatible software that are used in this project will also be discussed in this chapter.

Outline

this chapter includes the study of exoskeleton robot, elbow complex, classification of upper-limb exoskeleton robots, actuation system, power transmission system, dc motor, speed control by using PWM, full H bridge motor drive, delay and principle of gyro meter sensor‘s operation. It‘s also included some study about all related hardware and software that are used during process of completing this project, like microcontroller, PIC start-up kit, dc motor, gyro sensor, Proteus, MikroC, Arduino and Solid works.

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2.1.1 Exoskeleton robot

[image:17.595.218.392.315.472.2]

An exoskeleton robot is a wearable motion assist device consisted with actuators and sensors whose joints correspond to those of the human body .It is worn by the human and the physical contact between the user and the exoskeleton allows direct transfer of mechanical power and information signals. In utilizing the exoskeleton robot, the user provides the control signal for the exoskeleton, while the exoskeleton actuator provides most of the power necessary for performing the power assist [1]. Figure 2.1 show a 7 DOF exoskeleton robot developed at University of Washington, USA. [2]

Figure 2.1: Human Upper Limb Motion Assist Exoskeleton Robots. [2]

2.1.2 Elbow complex

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[image:18.595.185.426.71.198.2]

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Figure 2.2: Elbow complex and elbow motions. (a) Elbow anatomy. (b) Elbow flexion/extension motion. (c) Forearm supination/pronation motion. [3]

2.1.3 Classification of Upper-Limb Exoskeleton Robots

Upper-limb exoskeleton robots can be classified in several ways considering features of their mechanical designs and/or control methods. It‘s classified according to [4]:

a) Applied segment of the upper-limb

 Classified as hand exoskeleton robot, forearm exoskeleton robot, upper-arm exoskeleton robot or combined segment exoskeleton robot.

b) DOF

 Classified according to the number of active or passive joints or in other words DOF as 1DOF, 2DOF, 3DOF, etc.

c) power transmission methods

 Gear drive, cable drive, linkage mechanism or other method. d) Applications of the robot

 Classified according to the intended purpose namely rehabilitation robots, assistive robots, human amplifiers, haptic interfaces or other uses.

e) Control methods

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[image:19.595.146.463.74.150.2]

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Figure 2.3: Classification of exoskeleton robots. (a) Methods of classification of upper-limb exoskeleton robots. [4]

Figure 2.4: Classification of exoskeleton robots. (b) A classification of upper-limb exoskeleton robots based on the actuators used in mechanical designs. [4]

2.1.4 Actuation System

[image:19.595.140.469.212.405.2]
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2.1.5 Power Transmission System

[image:20.595.210.399.430.530.2]

Power transmission method of upper-limb exoskeleton robot depends on the actuator. With an electric motor, gear drives, cable (wire) drives and/or linkage mechanisms can be used to transmit power. Although electric motors can be used as direct drives, they are rarely used as direct drive in upper limb exoskeleton robots, since the size of the existing motors which can generates required upper-limb joint torques are rather large. Gear drives and/or cable drives have commonly been used in present upper-limb exoskeleton robots. Gear drives do not create slip as in the case of some cable drives. Also bevel gear drives can be used to transmit power between non-parallel axes. Therefore, compact joints can be designed for the upper-limb exoskeleton robot. Compact joints are important to the upper-limb exoskeleton robots used in daily motion assist. Backlash is inherent in gear drives. Also it is difficult to obtain precise back-drivability with gears. Therefore, gear drives should be carefully designed for the upper-limb exoskeleton robots. Since gear drives cannot be used to transmit power over relatively long distances, motors should be fixed near the actuated axis when gear drives are used for power transmission. [4]

Figure 2.5 Joint axis drive system. [5]

2.1.6 Speed Control by Using PWM

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[image:21.595.221.408.268.407.2]

approach cannot provide the desired flexibility and controllability is expensive. A better implementation method for PWM circuitry is to use the PWM functions available in many microcontrollers today. Most of the PIC 16 devices have PWM functions. Controlling the speed of the motor is an important area to be considered. The speed of motor is directly proportional to the DC voltage applied across its terminals. A PWM (Pulse Width Modulation) wave can be used to control the speed of the motor. Here the average voltage given or the average current flowing through the motor will change depending on the ON and OFF time of the pulses controlling the speed of the motor. The duty cycle of the wave controls its speed.

Figure 2.6: PWM (Pulse Width Modulation) [5]

As the amount of time that the voltage is on increases compared with the amount of time that it is off, the average speed of the motor increases and vice versa. The time that it takes a motor to speed up and slow down under switching conditions is depends on the inertia of the rotor (basically how heavy it is), and how much friction and load torque there is. Figure 2.7 shows the speed of a motor that is being turned on and off fairly slowly:

[image:21.595.227.406.581.683.2]
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2.1.7 Speed Control by Full H Bridge Motor Driver

[image:22.595.209.397.264.418.2]

A full bridge circuit is shown in the diagram below. Each side of the motor can be connected either to battery positive, or to battery negative and through a on-off switching MOSFET (Metal Oxide-Semiconductor Field Effect Transistor) which can turn very large currents on and off under the control of a low signal level voltage. Only one MOSFET on each side of the motor must be turned on at any one time otherwise they will short out the battery and burn out.

Figure 2.8: Full H bridge motor drive [5]

To make the motor go forwards, Q4 is turned on, and Q1 has the PWM signal applied to it. Meanwhile, to make the motor go backwards, Q3 is turned on, and Q2 has the PWM signal applied to it.

2.1.8 Speed Control by using MOSFET and delay

[image:22.595.175.437.582.704.2]
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[image:23.595.182.426.350.455.2]

The purpose of motor speed control is to control the speed, direction of rotation or position of the motor shaft. This requires that the voltage applied to the motor is modulated in some manner. Understanding the ratings of the motor is an important step in the process as it is often the corner points of operation that will determine the choice of the power switching element. The startup current (sometimes given as stall current or locked-rotor current) value can be up to three times the value of the steady-state operating current. This is where the power-switching element (bipolar transistor, MOSFET) is used in this project. By turning the power-switching elements on and off in a controlled manner, the voltage applied to the motor can be varied in order to vary the speed or position of the motor shaft. A relay (or magnetic relay or magnetic switch) is a switch operated by an electromagnetic action. The relatively small current flowing through a coil of an electromagnet inside pulls (or pushes) a lead contact to make (or break)a circuit. No current would push (or pull) back the contact by the mechanical spring attached to the mechanism

Figure 2.10: wiring diagram of delay [5]

2.2 Theory

This section includes the study about all related hardware and software that are used during process of completing this project. This theory section is divided into hardware and software and will be explain briefly.

2.2.1 Hardware

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2.2.1.1 Microcontroller

Basically, microcontroller is a small computer on a single integrated circuit containing a processor core, memory, and programmable input/output peripherals. The PIC microcontroller consist of over 400 variations consists of a number of memory configurations, amount of support hardware required, different I/O pin arrangements, packaging, and available peripheral functions.

Microcontroller input and output pins are available to communicate with the outside world or peripheral devices such as sensor, motor and LCD. The number of I/O pins per controllers varies greatly, plus each I/O pin can be programmed as an input or output (or even switch during the running of a program). The load (current draw) that can be driven by each pin is usually low. Therefore, it is important to use a driver chip or transistor buffer if the output is expected to be a heavy load.

[image:24.595.218.389.456.562.2]

There are a lot of advantages in using microcontroller such as the low cost factor which makes it very popular among students and hobbyists. Another advantage of microcontroller is the variety of programming software available and most of them are distributed as freeware such as MPLAB, MikroC, PICC and CCS.

Figure 2.11 Variety of microcontrollers available in the market

2.2.1.2 PIC microcontroller start-up kit

Figure

Figure 2.1: Human Upper Limb Motion Assist Exoskeleton Robots. [2]
Figure 2.2: Elbow complex and elbow motions. (a) Elbow anatomy. (b) Elbow
Figure 2.3: Classification of exoskeleton robots. (a) Methods of classification of
Figure 2.5 Joint axis drive system. [5]
+5

References

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