ece 3091 - final report-final

8/13/2019 Ece 3091 - Final Report-final

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Group 10: THE LIGHTSABER

MONASH UNIVERSITY SUNWAY CAMPUS

THE PEARL

HUNTERECE 3091

KESHAV RAMREKHA 21630283

TRIANDI TANRI 21827559

OMAR ABDULLAH 21837473


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ContentsList of Figures ................................................................................................................................................ 4

List of Tables ................................................................................................................................................. 5

Acknowledgement ........................................................................................................................................ 6

Abstract ......................................................................................................................................................... 7

Chapter 1 : Requirements Definition ............................................................................................................ 8

1.Introduction .......................................................................................................................................... 8

1.1 Objective ......................................................................................................................................... 8

1.2 Capabilities of the final prototype .................................................................................................. 9

1.3 Purpose of this Report .................................................................................................................... 9

CHAPTER 2: LITERATURE REVIEW ............................................................................................................... 10

2. Introduction .................................................................................................................................... 10

2.1 Robot 1: Line following robot (MOBOT competition) ....................................................................... 10

2.2 Robot 2: Hyper Squirrel..................................................................................................................... 11

2.3 Robot 3: The $50 Robot with Sharp IR edge detection .................................................................... 12

2.4 Robot 4: The OMNI-WHEEL ROBOT .................................................................................................. 13

2.4 Literature review conclusion ............................................................................................................ 14

CHAPTER 3: TEAM ORGANIZATION AND MANAGEMENT .......................................................................... 15

Introduction ................................................................................................................................................ 15

3.1 Planning Methods ................................................................................................................................. 15

3.1.1 Work Breakdown Structure ........................................................................................................... 15

3.1.2 Schedule for Network Activities (Critical Path Diagram) ............................................................... 16

3.1.3 Gantt Chart..................................................................................................................................... 17

3.1.4 Responsibility Matrix ..................................................................................................................... 19

3.1.5 Cost Estimation .............................................................................................................................. 20

3.1.6 Risk analysis ................................................................................................................................... 21

CHAPTER 4: THE LIGHTSABER DESIGN (Prototype 1).................................................................................. 224. THE SUB-SYSTEMS ........................................................................................................................... 22

Introduction ........................................................................................................................................ 22

4.1 Mechanical sub-system ................................................................................................................. 22

4.2 Locomotion sub-system ................................................................................................................ 24

4.3 Electronics Sub-system ................................................................................................................. 26

4.4 Pearl Detection and Collection ..................................................................................................... 30

4.5 Assessment of Prototype 1 ........................................................................................................... 34

CHAPTER 5: The Lightsaber (Prototype 2) .................................................................................................. 37


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5.1 Faults identified ................................................................................................................................ 37

5.2 Prototype 2The Design .................................................................................................................. 38

5.2.1 Mechanical sub-system .............................................................................................................. 38

5.2.2 Locomotion sub-system ............................................................................................................. 39

5.2.3 Electronics Sub-system .............................................................................................................. 40

5.2.4 Pearl Detection and Collection .................................................................................................. 42

CHAPTER 6: Evaluation ............................................................................................................................... 46

6.1 Problems and Solutions .................................................................................................................... 46

6.1.1 Hardware ................................................................................................................................... 46

6.1.2 Software ..................................................................................................................................... 47

6.2 Improvements and Optimization ...................................................................................................... 47

6.3 The Final Competition ....................................................................................................................... 48

6.3.1 Match 1 ...................................................................................................................................... 48

6.3.2 Match 2 ...................................................................................................................................... 49

6.3.3 Match 3 ...................................................................................................................................... 50

6.3.4 Match 4 ...................................................................................................................................... 50

Conclusion ................................................................................................................................................... 51

References .................................................................................................................................................. 52

Appendix ..................................................................................................................................................... 53

Appendix ATesting Scheme for Prototype 2 ....................................................................................... 53

i. Chassis strength .......................................................................................................................... 53

ii. Speed .......................................................................................................................................... 54

iii. The 90oleft turn .......................................................................................................................... 54

iv. Battery Life .................................................................................................................................. 55

Appendix BFull Code written for the Arduino Duemilanove .............................................................. 56


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List of FiguresFigure 1: The platform of the black pearl project ......................................................................................... 8

Figure 2: Final Prototype ............................................................................................................................... 9

Figure 3: Design layout of the Pikachu robot .............................................................................................. 10

Figure 4: Design layout of the Hyper Squirrel robot ................................................................................... 11

Figure 5: Design layout of the $50 robot robot .......................................................................................... 12

Figure 6: Design layout of the omni wheel robot ....................................................................................... 13

Figure 7: Work breakdown Chart ................................................................................................................ 15

Figure 8: Critical Path Diagram ................................................................................................................... 16

Figure 9: Gantt Chart Table ......................................................................................................................... 17

Figure 10: Gantt chart Timeline .................................................................................................................. 18

Figure 11: Design layout of the chassis ....................................................................................................... 22

Figure 12: Design layout of the chassis (side view) .................................................................................... 23

Figure 13: Design layout of the chassis (top view) ..................................................................................... 23

Figure 14: Actual view with top layer mounted (side view) ....................................................................... 23

Figure 15: Tamiya Double Gearbox schematics .......................................................................................... 24Figure 16: Actual view with wheels under test ........................................................................................... 25

Figure 17: Initial prototype with wheels mounted on chassis .................................................................... 25

Figure 18: L293D H-bridge .......................................................................................................................... 26

Figure 19: H-bridge circuit connection ....................................................................................................... 27

Figure 20: H-bridge circuit connected to wheels ........................................................................................ 28

Figure 21: IR sensor circuit .......................................................................................................................... 29

Figure 22: Arduino Duemilanove microcontroller ...................................................................................... 29

Figure 23: The main circuitry as seen on top of the Lightsaber .................................................................. 30

Figure 24: Pearl Detection and Collection method ..................................................................................... 31

Figure 25: Flowchart for algorithm of Prototype 1 ..................................................................................... 32

Figure 26: Pearl detection and collection ................................................................................................... 33

Figure 27: The new design for the chassis (widened chassis) ..................................................................... 38

Figure 28: The new design for the chassis (increased stability) ................................................................. 39

Figure 29: Addition of ball casters to the chassis ....................................................................................... 39

Figure 30: Use of the Sharp IR rangefinder for wall and robot detection and avoidance .......................... 40

Figure 31: Use of the Sharp IR rangefinder for wall and robot detection and avoidance .......................... 41

Figure 32: Flowchart for Prototype 2 .......................................................................................................... 42

Figure 33: Start of Algorithm (Path 1) ......................................................................................................... 43

Figure 34: Path 2 ......................................................................................................................................... 44Figure 35: Path 3 ......................................................................................................................................... 44

Figure 36: Path 4 ......................................................................................................................................... 45

Figure 37: Lightsaber Prototype 2 ............................................................................................................... 48

Figure 38: Inability to return to base after getting stuck ............................................................................ 49

Figure 39: New path taken after confusion ................................................................................................ 50

Figure 40: Deflection of chassis frame ........................................................................................................ 53

Figure 41: The 90oleft turn ......................................................................................................................... 54
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List of Tables

Table 1: Tabular Comparison of the 4 robots ............................................................................................. 14

Table 2: Responsibility Matrix ..................................................................................................................... 19

Table 3: Cost Estimation ............................................................................................................................. 20Table 4: Risk Assessment ............................................................................................................................ 21

Table 5: Table of number of pearls collected ............................................................................................. 34

Table 6: Table showing drop in voltage levels of batteries (powering H-bridge and sensors) ................... 35

Table 7:Table showing drop in voltage levels of battery (powering Arduino)............................................ 35

Table 8: Table describing faults identified in Prototype 1 .......................................................................... 37

Table 9: Table for hardware problems and solutions ................................................................................. 46

Table 10: Table for software problems and solutions ................................................................................ 47

Table 11: Table of improvements and Optimization performed ................................................................ 47

Table 12: Table of weight v/s deflection ..................................................................................................... 53

Table 13: Speed v/s stability ....................................................................................................................... 54

Table 14: Table of speed v/s angle .............................................................................................................. 55

Table 15: Battery life of LiPo battery .......................................................................................................... 55


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Acknowledgement

First and foremost, we would like to thank Dr. Melanie Ooi, the lecturer for ECE 3091. Dr. Ooi proved

to be very helpful and was a constant source of encouragement and motivation which helped

towards the completion of this project. Our thanks and gratitude also goes to the lab technicians, Mr.

Paremanan and Mr. Hasnan, for always being ready to help us with our needs and providing us with

all the necessary assistance required in the lab. Last but not least, our thanks go to our friends, who

have been constantly helping us out in any way possible, be it to solve a technical problem, or to

hang out and relax for a while.

--

Members of Group 10:

Keshav Ramrekha

Triandi Tanri

Omar Abdullah


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Abstract

Autonomous robots are intelligent machines capable of performing tasks pre-programmed into

them. But for them to perform, proper research, planning, testing and debugging must be carried

out. Some people ask themselves Who would we be without machines? and the answer is often

another question: What would machines be without men? Food for thought? The following report

gives an insight about the behind-the-scenes of this project which sees The Lightsabercoming to

life. From a single rough sketch to a fully operational robot, this report is the work of three young

minds put together.


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Chapter 1: Requirements Definition

1. Introduction1.1 Objective

The objective of this project is to design and build a robot which has the ability to collect allpolystyrene balls provided in the platform and bring them back to base within a specified time limit,

while at the same time preventing other enemy robots from stealing from the home base. The base

is defined as one of the corner encircled by an arc line. The purpose of this project is to apply the

acquired knowledge in circuit theory and programming onto real life application likewise building

the robot in this Pearl Hunter project. Furthermore, students are able to develop problem solving,

self-independent and cooperative skills throughout this project.

Figure 1: The platform of the black pearl project


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1.2Capabilities of the final prototype

Figure 2: Final Prototype

In this project, sensors are used as guidance to navigate the robot and also to locate the polystyrene

balls. A number of implementation issues did surface, but were solved. The final prototype is

capable of navigating its way in the arena and carry the polystyrene balls back to the base. It is also

able to prevent wall collision and avoid being hit by enemy robots.

1.3 Purpose of this Report

This report comprises the summarized version of the project planning, design description, algorithm,

testing scheme and also the problems that the group has encountered during the brainstorming

stage circuit design stage assembly stage test and evaluation stage debugging and

optimization stage. Moreover, this report explains the required specification for all components in a

very clear manner that errors and risk can be identified easily so improvements and optimizations

can be conducted to increase the reliability of the complete system. .


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CHAPTER 2: LITERATURE REVIEW

2.IntroductionThis section will provide information about the research carried out in order to gather ideas andbrainstorm for solutions as to how to build and improve The Lightsaber. Research was carried out on

various platforms and ideas gathered were then put together for a selection.

2.1 Robot 1: Line following robot (MOBOT competition)

The robot was initially built to compete in the MOBOT competition. The robot is a line following robot

capable of following a white strip line on different surfaces in an outdoor environment without its

performance being compromised by external conditions (lighting, wind, surface).

The robot chassis was made out of plastic board with servo motors used as wheels. A custom

microcontroller was used, with the circuit design soldered on a veroboard to minimize use of space and

to be very light.

The robot was fitted with color sensors to detect the white line and to be move forward.

While the overall performance of this robot was quite impressive, there were quite a number of issues

to solve before finally getting a decent overall performance. IR emitter/detector can easily be flooded by

Figure 3: Design layout of the Pikachu robot


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sunlight and be made useless. Without these, performance of robot is compromised. It is essential to

make sure the sensors are well shielded to get good results.

Varying surfaces and levels were also a problem, as the robot needs to adapt to its surroundings and be

able to brake to avoid collisions or going off-track. A DC motor braking technique can therefore be usedin this case.

The robots performance can be improved by adding a camera to navigate through the course. This,

while being a good idea, will increase workload and increase complexity of design and coding.

While this robot is fairly easy to understand and make, it lacks a few features required as part of what

the robot to be designed for ECE 3091 needs.

2.2 Robot 2: Hyper Squirrel

The Hyper Squirrel is a robot which can perform high speed reactive mapping. The robot travels at fast

speeds while making decisions on directions based on input from its sensors.

The robot makes use of 2 Sharp IR Rangefinders mounted on a servo motor which scan the environment

the robot is placed in and can navigate on its own.

The robot was built using acrylic as chassis and treads from a toy car for wheels. This enabled it to

navigate through any rough surfaces without any problem.

While the rangefinders were used to navigate around, 2 sets of IR emitter-detectors were used as

bumper sensors to avoid any collisions with unwanted objects or walls.

Figure 4: Design layout of the Hyper Squirrel robot


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The Hyper Squirrel is a very interesting project and surely can be used as base for comparison for this

current project. The treads make interesting motion wheels and the high-tech advanced mapping

technique used by this robot is a very interesting prospect that could be used to find and collect the

balls for this current project. The design will however need to be customized and modified so that a ball

collection mechanism can be added to the robot which has to fit in the specific constraints set for this

project.

2.3 Robot 3: The $50 Robot with Sharp IR edge detection

This is by far the easiest and perhaps the most interesting robot of its kind. It is made up of easy to find

materials and costs less than $50.

The robot uses a piece of acrylic as chassis, and 2 pieces of cardboard cut in circular shape for wheels.

These are rotated by means of 2 servo motors.

The Sharp IR rangefinder is used to make the robot go through its surroundings while avoiding obstacles

and walls.

Main advantages of this robot were the low costs of building and fairly easy level on of understanding

required to build it. The performance on the other side was very basic while not having great purpose.

The robot could however be easily modified and improved once built and working.

Figure 5: Design layout of the $50 robot robot


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2.4 Robot 4: The OMNI-WHEEL ROBOT

This robot is one of the most interesting in its kind and perhaps the most complicated as well. It uses a

series of Omni-wheels that can move in any direction at any angle without any prior rotation. This

mechanism can be considered for the current project as the polystyrene balls are scattered all over thearena, and our robot needs to be able to move in any direction to move and collect them.

The Omni-wheel robot is a very advanced piece of robotics, including 3 Sharp IR rangefinders

performing 2D mapping as part of an intelligent navigation system. In addition to those, 3 sonars acted

as obstacle detection and avoidance system, while 2 pairs of infrared emitter/detector sets were used

for line following system.

The omni-wheel robot is one of the best of its kind and built for a specific purpose. But while its superb

features make it a hard-to-neglect choice, the cost of purchasing all the items needed to build it by far

exceeds the budget limit we are allocated. Budget aside, the fuzzy logic algorithm and coding knowledge

required to make it function is sadly one of the qualities we lack for now and would prove a very

challenging task to get it right at the very first attempt.

Figure 6: Design layout of the omni wheel robot


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2.4 Literature review conclusion

Table 1: Tabular Comparison of the 4 robots

Key points identified during literature review:

Size:

Lightsaber needs to be small in size to enable all sorts of movements. Also, as per the set requirements

of the project, the robot needs to fit a 20cmX20cm size.

Speed:

Lightsaber needs to be fast to be able to collect as many balls as possible during the allowed 5 minutes

time limit.

Consistency:

Lightsaber needs to be consistent in the runs, being able to bring the pearls back to base on as many

runs as possible.

Cost:

Lightsaber needs to be built by using materials which do not exceed the set limit of RM300.

Robot Advantages Disadvantages

Line Follower Small Simple design Ability to detect white

lines and help with

motion

Inability to perform morecomplex operations

No ball catching mechanismHyper Squirrel System uses high speed

reactive mapping

Very robust design Can easily detect objects

around the arena and

move to them

Complex software Conveyor belt wheels provide

too much friction and limit

motion

Heavy chassis$50 robot Simple design

Cheap Materials readily

available

No specific function Not robust No ball collection system Movement limited by cardboard

wheels


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CHAPTER 3: TEAM ORGANIZATION AND MANAGEMENT

Introduction

No teamwork can be a one-man show and this project was not an exception. To achieve the aims set,

the team members worked closely together to be able to be successful. This chapter will detail the work

to be done by each team-member and provide a work timeline as well as a proper budget breakdown of

the project.

3.1 Planning Methods

3.1.1 Work Breakdown Structure

Group Members:

- Keshav Ramrekha (KR)- Triandi Tanri (TT)- Omar Abdullah (OA)

Figure 7: Work breakdown Chart

"Black PearlProject"

Hardware

Assembling frameof robot - KR, TT, OA

Assembling motorgearbox - KR

Electrical

Build sensors/leverswitches- OA

Build H-driversmotor circuit - TT

Software

Programming - KR,TT


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3.1.2 Schedule for Network Activities (Critical Path Diagram)

This is also another project modeling technique that is used to determine the priority of each element and the most effective path or critical

path that must be undertaken for the project to develop according to the proposed time.

Figure 8: Critical Path Diagram


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3.1.3 Gantt Chart

This is a type of a bar chart that displays the data of the project schedule. They include the start and

finish dates of each element in the project schedule. They also include the amount of time required to

be spent on each element of the project and identifies the team members responsible for each element

in the project schedule. The summary elements comprise of the work breakdown structure.

ID Task Name Start Finish Duration

11d8/12/20117/29/2011Research/Planning

6d8/5/20117/29/2011Motor Gear Ratio

10d8/11/20117/29/2011Robot Design and Layout

8d8/9/20117/29/2011IR sensors

8d8/9/20117/29/2011Phototransistors

2d8/11/20118/10/2011Assembly

1d8/9/20118/9/2011Motor Assembly

1d8/10/20118/10/2011Toggle Switch

10d8/23/20118/10/2011Design

1d8/10/20118/10/2011Robot Dimensions

9d8/23/20118/11/2011Framework

5d8/18/20118/12/2011Testing

1d8/12/20118/12/2011Wheel balancing

4d8/17/20118/12/2011Sensor Sensitivity

6d8/22/20118/15/2011Robot Construction

3d8/17/20118/15/2011Circuit building

3d8/19/20118/17/2011Circuit Troubleshooting

35d9/30/20118/15/2011Software

10d8/26/20118/15/2011Research Algorithm

10d9/23/20119/12/2011Testing

10d9/9/20118/29/2011Coding

5d9/28/20119/22/2011Debugging

15d10/19/20119/29/2011Finishing

5d10/3/20119/27/2011Coding Finalization

6d10/10/201110/3/2011Robot Finalization

15d10/19/20119/29/2011Final Testing

7d8/18/20118/10/2011Requirement Analysis

11d8/29/20118/15/2011Design Specifications

Figure 9: Gantt Chart Table


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18Figure 10: Gantt chart Timeline


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3.1.4 Responsibility Matrix

This is a matrix that identifies all the elements in the project schedule and displays the priority

of the team members effort in each and every element. This management technique allows

you to clarify the team members responsibilities in each task and displa ys whether there was

efficient communication between the assigned team members by viewing their priority in the

each specific task.

Task KR OA TT

Brainstorming

Layout of Robot P S P

Algorithm P S P

Components S P P

Hardware

Motor Gear Box P S S

Robot Frame P P P

Electrical

Sensors S P P

H-Bridge S S P

Software

Ball Detection Algorithm P S P

Ball Collecting Algorithm P P S

Testing

Wheel Balancing Test P S S

Sensor Sensitivity Test S P S

Ball Collecting Algorithm P P S

Full Testing P P P

Documentation

Requirement Analysis P P P

Design Specification P P P

Presentation P P P

Final Report P P PTable 2: Responsibility Matrix

Note:Primary Responsibility (P)

Secondary Responsibility (S)


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3.1.5 Cost Estimation

This method was done in order to estimate the cost of all the products that had to be bought in

the implementation of the robot. This method gives us a rough estimate of the costs of each

product for future reference and also determines the budget of the robot.

Table 3: Cost Estimation

Tools Quantity Price/unit (RM) Suppliers Price(RM)

Diagonal Cutting Pliers 1 - Monash -

Wire Cutter 1 - Monash -

Wire Stripper 1 - Monash -

Solder Sucker 1 - Monash -

Precision Screwdrivers (set) 1 - Monash -

Duwell Needle Files (set) 1 - Monash -

Insulation Tape 3 1.00 Ace Hardware 3.00

Materials Quantity Price/unit Suppliers

Plastic-board 2 3.00 Popular 6.00Polystyrene board 1 5.00 Popular 5.00

Bolts and Nuts several - Monash -

Bread Board 3 - Monash -

AAA Battery 6 - Monash -

AA Battery (rechargeable) 2 - Monash -

9V Battery (rechargeable) 1 - Monash -

9V Battery connector 1 - Monash -

Ball Caster 2 10.00 Cytron 10.00

Battery Holders 3 2.004.00 Ace-hardware 8.00

Gear Box 2 - Monash -

Electrical components Quantity Price/unit Suppliers

Micro-controller Board 1 - Monash -Sharp IR Rangefinder 1 55.00 Cytron 55.00

Ribbon Cable 3 - Monash -

9V Battery Connector 1 - Monash -

IC (H-drivers) 1 - Monash -

Push Switches 4 0.50 Ace Hardware 2.00

Sensors 7 2.00 JalanPasar 14.00

Servo Motor 2 20.00 E-shore 40.00

Maximum budget : RM 300.00 Total 143.00


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3.1.6 Risk analysis

Hazard

No.Description of Hazard Corrective Actions/ Risk Controls

H4 Electrical hazard such as contact with any electrical

conductor resulting in current flow to the body

Consequence Likelihood Risk

Severe Injury Unlikely Low

Make sure everything is assembled properly before switching on

the power supply

Timing Responsibility

During wire connection KR, OA, TT

R34 Cause burns


Minor Injury Unlikely Low

Wear protective gloves and glasses


During soldering KR, OA, TT

E3 Prolong repetitive movement/position


Minor Injury Unlikely Low

Take 5 minutes break for every hour sitting in front of computer

Proper lighting, comfortable working environment


During programming KR, OA, TT

Table 4: Risk Assessment


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CHAPTER 4: THE LIGHTSABER DESIGN (Prototype 1)

The Initial Design

4. THE SUB-SYSTEMSIntroduction

No project consists of one main system, no matter what the nature of the project is. To facilitate work

distribution and verification and problem solving, a problem is always broken down into sub-systems. In

the case of The Lightsaber, the project was divided into four main sub-systems; the mechanical sub-

system, locomotion sub-system, electronics sub-system and the pearl detection and collection sub-

system. The following sections describe the system in greater details.

4.1 Mechanical sub-system

After a brainstorming session, the mechanical sub-system was the first issued tackled by the group. The

mechanical part is one of the most important parts of the Lightsaber. This will be the whole body of the

robot and needs to be very stable and reliable. All other sub-system will be linked to the mechanical part

enabling proper functioning of the robot. As the need to be light and fast was clearly identified, the

materials chosen to build the chassis were plastic-board, polystyrene and tape (double-sided and

normal). These materials are readily available and are cheap.

Figure 11: Design layout of the chassis


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Figure 12: Design layout of the chassis (side view)

Figure 13: Design layout of the chassis (top view)

Figure 14: Actual view with top layer mounted (side view)


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4.2Locomotion sub-systemThe main aim of this project is to have an autonomous robot which is to be used to detect and collect

the pearls and return back to base. To be able in this task, motion of the robot is essential. For the robot

to move, wheels with a proper gearbox are used.

In this case, the group was provided with a set of Tamiya Double Gearbox system with adjustable gear

ratios for different scenarios.

The main aim of the project was to get a fast moving robot. Therefore, the gear ratio to be chosen had

to be enough to be able to provide enough torque for the Lightsaber to move fast.

Figure 15: Tamiya Double Gearbox schematics

There are four different gearbox designs that are shown in the above diagram and out of this four, two

were tried out and tested. The two choices that were considered are Aand B.

A344:1This is the design that provides the highest torque but results in a very slow rotationof the wheel.

B- 114.7:1- This is the design that provides the second most torque but provides a largerincrease in speed than A.

The other two were not chosen since the speed of the wheel would be too fast for easy smoothnavigation.

A

B


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Figure 16: Actual view with wheels under test

Figure 17: Initial prototype with wheels mounted on chassis


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4.3Electronics Sub-systemThe electronics sub-system acts like the bridge between the microcontroller and the mechanical system.

It is the part that allows all motion to be possible, and at the same time is the carrier of messages from

one component to the other.

To power the wheels, a dual H-bridge was used.

H-Drivers are used for the motor circuit as an integrated chip acts as a controller that connects the

batteries, motors and I/O pins from the micro-controller in just one IC. One H-Driverchip can control up

to two motors at the same instance.

Figure 18: L293D H-bridge


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Figure 19: H-bridge circuit connection

In the design of the robot, only one L293D quadruple half H-Drivers were used. After some trials, it is

found that both the motors for the wheel and also the servo motor could be controlled by just one H-

Drivers.

From the diagram above, the input voltage to the H-Driver is at pin 1, 8, 9, and 16. The minimum voltage

that must be supplied to the H-Driver in order to get the robot moving is around 5V and above to ensure

movement stability as some task that the robot has to perform requires more power from the motor

than the others.

This can be seen when the robot is doing a turn in which one of the motor have to turn clockwise and

the other, counter clockwise. From all the trials performed, it is noticed that when the input voltage to

the H-Driver is less than 4V the robot is unable to turn accordingly thus by making sure that the input

voltage is at least 5V and above, the problem is eliminate

Pins 2, 7, 10, and 15 are the I/O pins connected to the micro-controller. These pins are used for

controlling the direction of movements of the motors. For example, if pin 2 is set to 1 and pin 7 is set to

0 digital outputs, the motor will turn clockwise whereas if pin 2 is set to 0 and pin 7 is set to 1, the motor

will turn counter clockwise.

A dual H-bridge is a system component which allows control of 2 motors and allows rotation in both

clockwise and anti-clockwise direction. In the case of the Lightsaber, a L293D chip was used to control

rotation of motors.


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Figure 20: H-bridge circuit connected to wheels

The electronics subsystem also consists of the sensor circuits. In the case of the Lightsaber, sensors were

used for ball and wall detection. The sensors were connected to the main circuitry of the robot system

and powered through a common 5V rail.

The sensors used in this project are of infrared type and it is of the 5mm category. It works by the

photodiode sensing the amount of reflected energy/light, which is radiated by the transmitter, off any

surface. The photodiode will have distinctive output reading across its terminals for different colour

surface.

The IR sensor used in the design is based on the schematic provided by the school. The only variation did

to the schematic was the value of the pair of resistors used. The resistor used for the IR transmitter is

120 and the resistor used for the IR receiver is 4.7k .


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Figure 21: IR sensor circuit

After performing some test on the micro-controller to determine its threshold between logic 1 and 0,

the comparator is ignored and the output of the sensor is connected directly to the micro-controller.

The threshold voltage for the given micro-controller is 1.07 V. Any values lower than 1.7 V will be

interpreted as logic 0 and those above it will be logic 1.

The Arduino Duemilanove was used as the main microcontroller for the Lightsaber due to its small size

and lightweight.

The board is very small in size and is very light as well. This would be an advantage as it would not add

too much weight or take up too much space on the chassis. In addition to that, the Arduino, despite

being small in size, has a decent number of I/O ports, some of which can be used as PWM ports to

control speed/motion.

1204.7k

Figure 22: Arduino Duemilanove microcontroller


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Figure 23: The main circuitry as seen on top of the Lightsaber

4.4Pearl Detection and CollectionThis section is the most important section of the project as the main objective is to gather as many

pearls as possible in the home base. The initial design made use of the sensory feedback as main source

of information about pearls and their position.

The Sharp IR rangefinder was used to locate the pearls as the robot moved and calculated the distance

separating the distance from the robot to them. This helped the robot keep moving until it reached the

pearls. Once it reached the pearls, they would get into the holding area of the Lightsaber, where they

would cross the signal between the IR emitter and detector circuit.

This would in turn activate two servo motors, which acted like flaps to close and hold the pearls inside

the robot. This action would indicate to the robot to start the process of returning to base to drop the

pearls safely back into the home base.

Arduino DuemilanovH-Bridge

Sensors connected to common rail Battery holder for batteries to power circuit


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Figure 24: Pearl Detection and Collection method

Sharp IR

rangefinder used

to locate pearls

IR emitter/detector

to detect whether

pearl was inside

holding area

Pearl

Servo Motors close flaps

upon detection of pearls


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3.4.1 Ball Collection Algorithm

Start

Move Forward

Detect ball?Keep moving

Forward

Close Flaps

Turn 180 degrees

Move forward

Detect wall

Stop and release

balls

Reverse with preset

delay

NO

YES

YES

NO

Figure 25: Flowchart for algorithm of Prototype 1


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The algorithm on the previous page gives an overall idea of how the Lightsaber performed its task of

detecting and collecting the ball. It worked using a simple system of detection by using the Sharp IR

rangefinder and the IR emitter/detector pair was used to help holding on to the ball.

The robot will start moving and as soon as it detects a pearl, it will close the flaps, turn 180 o clockwise

and return to base. When it detects the wall of the base, it will stop, release the pearl by opening the

flaps, and then move backwards, turn to face the arena, but this time at another preset angle.

Pearls

Home

Base

Figure 26: Pearl detection and collection


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4.5.2 Battery Life

Battery life greatly affects performance of machines and the Lightsaber was no exception. As the testing

was done, battery life was considerably reduced and had to be replaced constantly. Rechargeable

batteries avoided extra cost of buying new ones, but at the expense of long waiting hours for charging to

be complete. The battery levels were regularly monitored to assess performance of the robot.

Set 1 Set 2 Set 3 Set 4 Set 5

Initial

Voltage

(Volts)

Final

Voltage

(Volts)

Initial

Voltage

(Volts)

Final

Voltage

(Volts)

Initial

Voltage

(Volts)

Final

Voltage

(Volts)

Initial

Voltage

(Volts)

Final

Voltage

(Volts)

Initial

Voltage

(Volts)

Final

Voltage

(Volts)

Trial 1 5.28 5.02 5.31 5.11 5.16 4.99 5.23 5.02 5.11 4.88

Trial 2 5.24 5.12 5.27 5.10 5.20 4.86 5.18 4.83 5.13 4.92

Trial 3 5.16 4.96 5.18 4.93 5.23 5.01 5.21 4.82 5.23 4.85

Table 6: Table showing drop in voltage levels of batteries (powering H-bridge and sensors)

Set 1 Set 2 Set 3 Set 4 Set 5

Initial

Voltage

(Volts)

Final

Voltage

(Volts)

Initial

Voltage

(Volts)

Final

Voltage

(Volts)

Initial

Voltage

(Volts)

Final

Voltage

(Volts)

Initial

Voltage

(Volts)

Final

Voltage

(Volts)

Initial

Voltage

(Volts)

Final

Voltage

(Volts)

Trial 1 9.66 9.36 9.58 9.21 9.67 9.35 9.59 9.32 9.55 9.12

Trial 2 9.55 9.15 9.52 9.07 9.36 9.01 9.32 8.99 9.30 9.06

Trial 3 9.35 8.95 9.23 8.93 9.21 7.96 9.17 8.23 9.13 8.29

Table 7:Table showing drop in voltage levels of battery (powering Arduino)


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4.5.3 Testing of individual components

4.5.3.1(IR emitter/detector circuit)

These components were responsible to check whether pearls were inside the holding area of the arena

or not. The result of that operation would then enable to servo motors to close the flaps. To check this

part, the same concept was used as for the previous section and the number of times it worked was

noted.

Again, a set of 5 runs over 2 minutes was carried out and repeated.

From the tests, it was noted that over the number of runs, only 6 times the sensors had failed to detect

a ball inside the holding area. This was either due to a wire coming out hence causing an open circuit or

the robot moving too fast and pushing the ball away before the sensors could react to the voltage

change.

4.5.3.2 Servo motors (flaps)

The servo motors were used to open or close the flaps to either keep hold of the pearls or release them

when in the home base.

Results were collected over the same number of runs as in the above section

From the tests, it was noted that over the number of runs, 9 times the servos had failed to open or close

the flaps. This was either due to a wrong connection out hence causing an open circuit or wrong output

from sensor readings causing the robot to ignore the decision.


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CHAPTER 5: The Lightsaber (Prototype 2)

After the old design was tested over and over again, a number of faults were identified and corrective

measures were to be taken to improve the performance of the robot.

5.1 Faults identified

Components Faults

Chassis Chassis started bending under weight of all other

components mounted on it. Caused robot to move in a

curved path.

Holding area not wide enough to hold many pearls at

one go.

Batteries The batteries proved a major issue with them

discharging fast and not providing enough power to the

wheels. Motion of robot became erratic after power

drops below full operating limit.

Pearl collection using sensory feedback The detection of pearls using data obtained from

sensors was not always reliable, since the number of

pearls detected and collected was low.

Servo motors Servo motors were found to be under the influence of

fluctuating voltage and often were found to close

without any signal sent to them. This caused the

Lightsaber to miss the pearls.

Table 8: Table describing faults identified in Prototype 1


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5.2 Prototype 2 The Design

For the prototype 2, the overall layout of the subsystems remained the same, with the same 4

subsystems as mentioned for prototype 1. However, some changes were made to the design and

components and are detailed below. The changes were made in order to correct and reduce the faultsidentified in the previous section

5.2.1 Mechanical sub-system

From the previous section it was observed that the chassis of the robot was not strong enough to

withstand heavy testing. It was then modified in order to make it stronger and more resistant.

The second issue noted was the fact that the holding area for pearls was not as wide as expected, and it

was therefore widened to allow more pearls to be held.

Figure 27: The new design for the chassis (widened chassis)


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To assist the robot in moving around the arena, a Sharp IR rangefinder was placed at the top of the

robot. It was programmed to detect walls and other robots, and stop and change directions if ever they

came into contact. The Sharp IR rangefinder also helped in the path algorithm used for ball collection,

which is described further down in this report.

Figure 30: Use of the Sharp IR rangefinder for wall and robot detection and avoidance

5.2.3 Electronics Sub-systemThe main components of the electronics sub-system were kept unchanged, although a few changes

were made. The servo motors were removed as well as the IR emitter/detector circuits. The

rechargeable batteries used for prototype 1 were all replaced by a single LiPo battery.

The main reason for replacing all the batteries with a single LiPo battery was the improved performance,

greater power and longer running hours on a single charge. The robot was found to be able to run

smoothly for 2.5 hours on a single charge.

Both the Arduino and the H-bridge circuitry were powered by the LiPo battery. This also helped reduce

overall weight of the robot and with the battery placed at the center of the bottom layer of the robot;

the center of gravity was made lower, thus improving stability of the robot.

Sharp IR

rangefinder, for

wall and robot

detection


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Figure 31: Use of the Sharp IR rangefinder for wall and robot detection and avoidance

Arduino

Microcontroller

H-bridge

Switch to ON/OFF

the robot

Sharp IR rangefinder

powered straight

from Arduino


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5.2.4 Pearl Detection and CollectionFor the prototype 2, the whole algorithm for ball collection changed, as this time a pre-defined motion

path was programmed into the microcontroller.

It was noted that in the case of prototype 1 that allowing the robot to move by using the sensors was

erratic and a lot of errors were introduced due to unstable chassis, incorrect wheel alignment and wrong

return to base movement.

The use of a predefined path allowed a more consistent navigation of the robot, with it moving

according to the program and returning to base before moving out again. The path algorithm is shown in

the pictures below.

Figure 32: Flowchart for Prototype 2


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The robot starts to move from point A in the above diagram until it reaches the wall where it turns 900

anti-clockwise. It then detects a second wall where again it turns 90 Oanti-clockwise. It will then move

until it reaches the wall of the home base, and will reverse until it reaches point B.

A

B

Figure 33: Start of Algorithm (Path 1)

Home

Base


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From point B, it will turn 90oand move forward for 5 seconds and again turn 90o degrees anti-clockwise

and move forward until it reaches the wall. It will turn and follow the motion defined by the arrows until

it reaches point C.

B

C

Figure 34: Path 2

D

Figure 35: Path 3

Home

Base

Home

Base


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From Figure 30, the robot will move from position C, turn 90 o, follow a straight path for 7 seconds, and

then again turn left 90o and move until it reaches the wall. The same procedure is used to reach the

home base again with turning left each time the Sharp IR rangefinder detects a wall.

In path 4 (Figure 31), the robot will follow the path indicated by the arrows after it reaches point D in

Figure 30. The purpose of path 4 is to be able to steal the pearls from the enemy base and increase the

chances of winning.

In the end, the robot covers the area of the arena by covering it section by section using the algorithm

showed in the previous figures and each time returns to base to deposit any pearls collected on its way.

Home

Base

Figure 36: Path 4

Enemy

Base


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CHAPTER 6: Evaluation

One of the main issues about this project was the random scattering of the pearls all over the arena and

how to collect the pearls and come back to the home base. The whole competition depended on the

final number of pearls collected and brought back to base. The main concern was therefore to find theoptimized path and method to collect the most number of balls. After trying prototype 1 and noticing its

shortcomings, the design was changed to Prototype 2 and test runs were carried out.

It was found out that, after extended testing that the Lightsaber performed better while being on a pre-

defined course than on a to-and-fro path using sensor feedback. Prototype 2 was also found out to

move in a straight line better than prototype 1 due to its improved chassis and enhanced weight

distribution.

After the removal of the rechargeable AA and AAA batteries and the 9V battery, and replacing them

with the new LiPo battery, it was found out that robot performed in a more consistent way with the

drop in voltage levels not as considerable as the previous batteries. The absence of the need to

constantly charge up the batteries made it easier to keep testing the robot and also maintaining

constant performance for long hours.

6.1 Problems and Solutions

6.1.1 Hardware

Table 9: Table for hardware problems and solutions

No Hardware

Problems

Cause & Evolved Solution

1 Sensor values

changing too fast

This was due to the motion of the robot. The sensor was secured properly with tape

and values smoothened out.

2 Driving motors

not rotating

This occurred mainly due to wires coming out of the breadboard. Proper connectors

were used to solve the problem.

3 Dying Batteries If the voltage supplied by the batteries is too low, the driving motors rotation speed

decreases, resulting in a slow forward motion of the robot and sometimes getting

stuck in one position while turning 90 degrees. All the batteries were replaced by a

single LiPo 8.4V battery which solved these problems.

4 Gearbox The initial gear-ratio chosen was for a light robot, however even when the robot

chassis was changed, performance did not drop so no change was made to the

gearbox.

6 Servo Motors The servo motors had faults of jerking without even a microcontroller input. This is

due to the connection between the servo and microcontroller not being fixed

properly. Servo motors were taken off for Prototype 2.


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6.1.2 Software

Number Software Problem Cause & Solution

1 Usage of delay in

coding to createPWM.

This is because the delay causes the drving motor rotation to

decrease. Therefore, the delay may cause the robot to move inadifferent speed for old batteries, likely slower and if new

batteries, it would increase the speed causing the hardware

problem stated before.

Solved by replacing batteries with a more powerful LiPo battery

which kept voltage at an almost high and constant level.

2 Coding issues and

inability of robot to

follow instructions

There were issues where the robot did not follow the code

programmed into the microcontroller. This problem was solved

by breaking down the whole software into small pieces and

testing individually and then compiling the whole code together

once issues were resolved.Table 10: Table for software problems and solutions

6.2 Improvements and Optimization

Prototype I Prototype II

Components one set of IR sensorsone Sharp IR rangefinderTwo wheel motorsOne ball caster as third wheelTwo servo motors as flaps

One Sharp IR rangefinderWidened holding area

Functions Capable of performing a to-and-for pearl detection and collection

Able to detect wallAble to return to base accurately

Weakness Unreliable motionDoes not always return to base At certain angle, wall or robotdetection may not work

Changes from

previous

prototype

N/A Servo flaps removedIR sensor circuit removedWidened holding areaImproved chassisNew LiPo batteryNot

applicable

reason

Inconsistency of sensors andunreliable chassis was major

issues.

No flaps to capture the polystyreneballs

Table 11: Table of improvements and Optimization performed


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6.3 The Final Competition

The final competition was the means by which the overall performance of the robot was to be tested in

matches against different opponents. In the competition everything ranging from robustness, creativity

to performance was assessed.

Prototype 2 competed in the competition and had the following specifications.

Size: 19x18cm (fits within preset 20x20cm limit) 1 IR rangefinder Arduino Duemilanove Microcontroller Breadboard containing connections and circuitry for H-Bridge Tamiya Dual Gearbox with gear ratio 114.7:1 1 Lipo 8.4V 1200maH battery

6.3.1 Match 1

During match 1, Lightsaber performed very well, managing to go through the entire path and algorithm

preset and collecting pearls on its way back to base. In the end, it collected 14 pearls with a minimum

amount of human interventions needed to help its motion. Eventually it ran out as winner of its match.No notable difficulty in navigation was observed. Design and algorithm was preserved.

Figure 37: Lightsaber Prototype 2


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6.3.2 Match 2

Match 2 was a totally different scenario, where the enemy robot had a different approach to the match.

This changed the game plans and soon after the match started, the 2 robots collided and had to be

taken back to base. However collision was not the only problem faced in this case. The Lightsaber got

stuck amongst pearls and therefore could not come back to base and had to be taken out. The same

situation repeated itself and the match was lost in the end as the opponent team collected more pearls.

In this match, there was also an example of preventing enemy robots stealing from the home base. The

strategy was to time the predefined paths in such a way that Lightsaber returned to home base at

regular intervals after completing the path motions. If ever an enemy robot were to come steal, it would

either collide on the way to the base or collide in the base, in which case, no pearls could be taken off

the home base.

Figure 38: Inability to return to base after getting stuck


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6.3.3 Match 3

Match 3 started well, with path 1 (mentioned earlier) completed well. However in this match versus

team Tornado, there was little that could be done to prevent the fan from blowing off all the pearls

from our home base and from the arena into the enemy base. Attempts were made to steal from enemy

base after path 4, but with the fan blowing hard the match was lost.

6.3.4 Match 4

Match 4 was a repeat of the scenario from match 2 with the Lightsaber again getting stuck due to a

collision with a few pearls at an angle. This prevented it from moving correctly and not returning to base

but instead moved to a second loop. It did however work after a human intervention was required, but

in the end lost the match due to a smaller number of balls collected compared to the opponent.

New path taken by

Lightsaber, after

getting confused.

Did not return to base

initially.

Figure 39: New path taken after confusion


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Conclusion

Throughout this project, electrical knowledge learned in Monash University is put to practice. Besides,

skills and teamwork cooperation are developed during the progress of the project.

The planning of the project is arranged properly that every group member has the fair responsibility in

this project. And the total cost used for this project is relatively affordable where it does not exceed the

maximum planned budget.

Although performance in the competition was not as successful as expected in terms of collection of

pearls, the robot has considerably high reliability in straight line motion and wall or robot detection and

avoidance. Have we had a little more chance to make a few more modifications to the robot, we would

have been able to achieve far better results.

In conclusion, we are successful in building a robot that is capable of fulfilling every requirement for this

project thus we feel a great sense of achievement in it.


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ReferencesSociety of Robots. (2011). Sensors: Sharp IR rangefinder. [Online]. Available:

http://www.societyofrobots.com/sensors_sharpirrange.shtml

Acroname Robotics. (2011). Sharp GP2Y0A21YK0F IR Package.[Online]. Available:

http://www.acroname.com/robotics/parts/R301-GP2Y0A21YK.html

Tamiya. (2011). Double Gearbox.[Online]. Available:

http://www.tamiyausa.com/product/item.php?product-id=70168

C. McManis. (2006). H-Bridges: Theory and Practice.[Online]. Available:

http://www.mcmanis.com/chuck/robotics/tutorial/h-bridge/

Price, D. A. Monash Minibot Version 1.0. 2005

Elecrom. (2008). How to make simple Infrared Sensor Modules. [Online]. Available:

http://elecrom.wordpress.com/2008/02/19/how-to-make-simple-infrared-sensor-modules/

Ikalogic. (n.d.). Line Sensors. [Online]. Available:

http://www.ikalogic.com/tut_line_sens_algo.php

HPhy. (n.d.). Schmitt Trigger. [Online]. Available:

http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/schmitt.html

OP AMPS. LF 324 Datasheet.(2010).

Silicon Labs. (2011). MCU Development Kits.[Online]. Available:

http://www.silabs.com/products/mcu/Pages/C8051F020DK.aspx

Arduino. (2011).ArduinoDuemilanove.[Online]. Available:

http://www.arduino.cc/en/Main/ArduinoBoardDuemilanove

Society of Robots. (2011). Mobot Competition.[Online]. Available:

http://www.societyofrobots.com/competitions_mobot.shtml

Society of Robots. (2011). Mobot 2007 Line follow robot tutorial.[Online]. Available;

http://www.societyofrobots.com/robot_mobot_2007.shtml

Society of Robots. (2011). Hyper Squirrel.[Online]. Available:

http://www.societyofrobots.com/robot_hyper_squirrel.shtml

Society of Robots. (2011). The $50 Robot.[Online]. Available:

http://www.societyofrobots.com/robot_50_robot_sharpIR.shtml

Society of Robots. (2011). Omni-Wheel Robot Fuzzy.[Online]. Available:

http://www.societyofrobots.com/robot_omni_wheel.shtml#fuzzy


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Appendix

Appendix A Testing Scheme for Prototype 2

The following pages will describe the testing procedures carried out on Prototype 2 and the discussion

of the results obtained.

i. Chassis strengthTo test the new chassis and whether it would be able to support the weight of the breadboard,

microcontroller and battery, a simple test was done whereby objects of varying weight were placed on

the chassis and the robot made to move. After a series of 10 test runs for each weight set, the chassis

was checked for deflection.

Figure 40: Deflection of chassis frame

Weight Deflection, (cm)

125g -

245g 0.2

330g 0.4

Table 12: Table of weight v/s deflection

The above table shows the deflection observed when different weights were applied. For small weights

the deflection was negligible. When the weight was increased, the deflection was about 0.2-0.4cm,

which was still very low. The total weight of the circuits, Arduino and battery did not exceed 300g and

therefore was well within the limit of negligible deflection.

Chassis was therefore reliable for operation with all the components integrated on it for the test runs.

Deflection,


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ii. SpeedTo test the speed of the robot, it was tested over a number of test runs. The test was to test the robot

with all the components on it and allow it to complete the predefined path. The robot having a

considerable weight now was tested at different PWM speeds to find an optimum PWM value to ensure

enough speed and stability in motion.

PWM Value Time taken to complete path Stability/Issues

150 3min 08s Too fast. Unstable

120 3min 48s Fast. Motion not entirely straight

100 4min 10s Stable

80 4min 32s Very Stable. Straight line motionTable 13: Speed v/s stability

From the above table it can be seen that the robot was found to move perfectly well in a straight line

motion with a PWM speed of 80. That speed was chosen for the competition as it offered great stability

and enabled the robot to move well within the time limit of 5minutes.

iii. The 90oleft turnTo be able to make the 90o left turn, a lot of testing was done to find the optimum PWM value that

would enable the robot to turn at 90o. A reference mark was set and deviation and angle calculated

from there.

Figure 41: The 90oleft turn

90oreference


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PWM value Delay Angle (estimated)

120 500 110

150 300 25

100 550 80

80 600 90

Table 14: Table of speed v/s angle

From the above table, the speed of 80 and delay of 600 was chosen to make the robot turn at 90O.

iv. Battery LifeThe battery life of the LiPo battery was tested over a series of test runs with initial value and final value

noted.

No of test runs Initial Value (V) Final Value (V)

15 8.34 8.30

20 8.28 8.17

25 8.23 7.99

50 8.20 7.64

Table 15: Battery life of LiPo battery

From the above table it can be noted that the voltage drop is not that considerable and the voltage level

still being above the average operating limit, the robot performed well even at a high number of test

runs. Charging time was only 25minutes for full charge, and was therefore an advantage over normal

rechargeable AA, AAA batteries which have a charging time of 8 hours for full recharge.


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Appendix B Full Code written for the Arduino Duemilanove

//18th October 2011

//Written by Triandi Tanri

//Modified by Keshav Ramrekha

#include

int motor_left[] = {3, 5}; //Define pins for left motor

int motor_right[] = {6, 11}; //Define pins for right motor

int wall = 4; //Initialize a counter for walls

int counter = 0; //Initialize counter

void setup() {

Serial.begin(9600);

pinMode(motor_left[1], OUTPUT); //Pin definitions

pinMode(motor_left[0], OUTPUT);

pinMode(motor_right[0], OUTPUT);

pinMode(motor_right[1], OUTPUT);

;

}

void loop(){ //Main loop

float walls = analogRead(wall)*0.0048828125; // Converting reading from sensor to voltage

Serial.println(walls);

forward();

if(counter2.5){

path_1();

}

else if(counter==2 && walls>2.2){

path_2();

}

else if(counter>2 && counter 2.5){

path_1();


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}


path_3();

}

else if(counter>5 && counter2.5){

path_1();

}


path_4();

}

else if(counter>8 && counter2.5){path_1();

}


backward();

delay(750);

left(80,80);

delay(600);

forward();delay(1500);

left(80,80);

delay(600);

forward();

delay(500);

counter = 0;

}

}

void path_1(){

counter++;

// backward();

// delay(400);

left(80,80);

delay(650);


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motor_stop();

delay(500);

forward();

delay(500);

}

void path_2(){

counter++;

backward();

delay(750);

left(80,80);

delay(620);

motor_stop();

delay(200);

forward();

delay(3000);

left(80,80);

delay(700);

forward();

delay(500);

}

void path_3(){counter++;

backward();

delay(750);

left(80,80);

delay(620);

motor_stop();

delay(200);

forward();

delay(4500);

left(80,80);

delay(700);

forward();

delay(500);

}


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void path_4(){

counter++;

backward();

delay(750);

left(80,80);

delay(500);

motor_stop();

delay(200);

forward();

delay(500);

}

//-----------MOTOR FUNCTIONS----------------//

void motor_stop(){

digitalWrite(motor_left[0], LOW);


digitalWrite(motor_right[0], LOW);


//delay(2000);

}

void forward(){

analogWrite(motor_left[0], 80);


analogWrite(motor_right[0], 80);


}

void left(byte a, byte b){

analogWrite(motor_left[1], a);

digitalWrite(motor_left[0],LOW);

analogWrite(motor_right[0], b);


//delay(1000);

}


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void right(byte a, byte b){

analogWrite(motor_left[0], a);


analogWrite(motor_right[1], b);


}

void backward(){

analogWrite(motor_left[1], 90);


analogWrite(motor_right[1], 90);


}