A

PROJECT REPORT

ON

“AUTONOMOUS ROBOT WITH ARM”

Submitted in Fulfillment for the Award of

Bachelor of Technology Degree

Of

Rajasthan Technical University, KOTA

2008-12

Submitted to: Submitted by:

MD. ASIF IQBAL PREM RANJAN (EE/08/19)

Assistant Professor RAJ SINGH REPASWAL (EE/08/20)

Department of Electrical Engineering SAUMYA GARG (EE/08/27)

PCE, Jaipur 4th

Year, EE, PCE

DEPARTMENT OF ELECTRICAL ENGINEERING

POORNIMA COLLEGE OF ENGINEERING

ISI-6, RIICO INSTITUTIONAL AREA

SITAPURA, JAIPUR-302022

(RAJASTHAN)

DEPARTMENT OF ELECTRICAL ENGINEERING

POORNIMA COLLEGE OF ENGINEERING

JAIPUR - 302022

CERTIFICATE This is to certify that the seminar report entitled “AUTONOMOUS ROBOT WITH ARM” is submitted

by PREM RANJAN (EE/08/19), RAJ SINGH REPASWAL (EE/08/20) & SAUMYA GARG (EE/08/27),

Students of IV Year, VIII semester in fulfillment of the degree of Bachelor of Technology in

Electrical Engineering of Rajasthan Technical University, Kota during the academic year 2011-12.

The report has been found satisfactory and is approved for submission.

MD. ASIF IQBAL MR. HARBEER SINGH MR. SHIVRAJ SHARMA DR. R. P. RAJORIYA

Project Guide Project Coordinator HOD, EE department Campus Director (PCE)

PCE/EE/iii

PREFACE

Today the world swiftly changing, there are multiple challenges faced by us. Surly it is

the knowledge through technology, which makes us to overcome them.

The project report, which is an integral part of four years engineering program provides a

platform to all the student to augment their technical study revelation. It is the time, which is

effectively used by students to enhance their interaction with technical atmosphere.

The project is obligatory as per university course outline. This project is based on work

done and theory gained during analysis of the topic. The report basically introduces working of

project in detail.

In this project we worked in the development of an Autonomous Robot with Arm which

can move in any direction and pick up and put down things. It is capable of many capabilities

like it is fully remote controlled and can pick objects of 50 grams approximately. It can take the

object, hold it and put it anywhere of its reach, even to some height. It only works on 220V A.C.

supply.

We have been fortunate to get a chance for making the seminar under guidance of Md.

Asif Iqbal, Assistant Professor, Department of Electrical Engineering.

We hope, this report will make the learning of the facts are warding experience and will

have away for future study.

This report is true to best of my knowledge.

PREM RANJAN

RAJ SINGH REPASWAL

SAUMYA GARG

PCE/EE/iv

ACKNOWLEDGEMENT

We take this opportunity to express our deep sense of gratitude and respect towards our project

guide Md. Asif Iqbal, Assistant Professor, Department of Electrical Engineering. We are

very much indebted to him for his generosity, expertise and guidance; we have received from

him while working on this project and throughout our studies. Without his support and timely

guidance, the completion of our project would have seemed a farfetched dream. In this respect

we find ourselves lucky to have him as our guide. He has guided us not only with the subject

matter, but also taught us the proper style and techniques of working.

We are grateful to our respected Dr. R. P. Rajoria (Campus Director), Dr. Om

Prakash Sharma (Principal), Mr. Shivraj Sharma (HOD, EE Dept.) and Mr. Harbeer Singh

(Project Coordinators) and all the staff members of Department of Electrical Engineering for

their constant encouragement and all those who helped us directly or indirectly in our endeavor.

PREM RANJAN

RAJ SINGH REPASWAL

SAUMYA GARG

PCE/EE/v

CONTENTS

CERITFICATE ……ii

PREFACE ……iii

ACKNOWLEDGEMENT ……iv

CONTENTS ……v

FIGURE INDEX ……viii

ABSTRACT ……ix

CHAPTERS

1. Introduction 1

1.1 Embedded System 1

1.2 Variety of Embedded Systems 2

1.3 Microcontrollers 4

1.4 Embedded Design of Microcontroller 5

1.4.1 Interrupts 6

1.4.2 Programs 6

1.4.3 Other Microcontroller Features 7

2. Autonomous Robot with Arm 9

2.1 Aims 9

2.2 Objectives 9

2.3 Project Restrictions 9

2.4 Individual Task 10

2.4.1 IR Transmitter 10

2.4.2 IR Receiver 12

2.4.3 Signal Processing 13

2.4.4 Robot Movement 14

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2.4.4.1 Straight – Forward 14

2.4.4.2 Straight – Backwards 15

2.4.4.3 Point Turn – Right 15

2.4.4.4 Point Turn – Left 16

2.4.4.5 Swing Turn - Forward Right 16

2.4.4.6 Swing Turn - Backward Right 16

2.4.4.7 Swing Turn - Forward Left 17

2.4.4.8 Swing Turn - Backward Left 17

2.4.5 Arm Movement 18

2.4.6 Power Supply 18

2.4.7 Body/Chassis 19

2.4.8 Motor Control 20

3. Circuit Diagram 21

3.1 Microcontroller ATmega8 22

3.1.1 Pin Configuration 22

3.1.2 Features 24

3.2 Motor Driver IC L293D 26

3.3 Crystal Oscillator 27

3.4 7805 Voltage Regulator IC 28

3.5 Stepper Motor 29

3.6 Infra-red Remote 31

3.7 Power Supply 32

3.7.1 Transformer 33

3.7.2 Bridge rectifier 34

3.7.3 Smoothing 35

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3.8 Resistors 37

3.9 Condensers/Capacitors 37

3.10 Inductors 38

3.11 Diodes 38

3.12 Transistors 39

3.13 ICs (Integrated Circuits) 39

3. 14 Microprocessors (MPUs) 39

4. Coding 41

5. Conclusion 48

6. References 49

PCE/EE/viii

FIGURE INDEX

Figure 2.1: IR Transmitter 11

Figure 2.2: IR Receiver 12

Figure 2.3: Straight – Forward 15

Figure 2.4: Straight – Backwards 15

Figure 2.5: Point Turn – Right 15

Figure 2.6: Point Turn – Left 16

Figure 2.7: Swing Turn - Forward Right 16

Figure 2.8: Swing Turn - Backward Right 17

Figure 2.9: Swing Turn - Forward Left 17

Figure 2.10: Swing Turn - Backward Left 17

Figure 2.11: Arm Movement 18

Figure 2.12: Chassis 19

Figure 3.1: Circuit Diagram 21

Figure 3.2: Pin Configuration 22

Figure 3.3: Block Diagram of Microcontroller ATmega8 23

Figure 3.4:- Motor Driver IC L293D pin diagram 26

Figure 3.5:- Block Diagram of L293D 27

Figure 3.6:- 7805 Voltage Regulator IC 29

Figure 3.7:- Stepper Motor 30

Figure 3.8: Remote 31

Figure 3.9: Circuit Diagram of regulated power Supply 32

Figure 3.10: Bridge rectifier 35

Figure 3.11: Output: full-wave varying DC 35

Figure 3.12: Smoothing 36

PCE/EE/viii

ABSTRACT

In this project we worked in the development of an Autonomous Robot with Arm which

can move in any direction and pick up and put down things. It is capable of many capabilities

like it is fully remote controlled and can pick objects of 50 grams approximately. It can take the

object, hold it and put it anywhere of its reach, even to some height. It only works on 220V A.C.

supply.

When we press a button on remote, it sends a signal to our robot circuitry where our

receiver will decode it and sends the signal to the IC. It makes the various functioning motors

move and thus the whole robot moves accordingly. We used microcontroller for its coding,

various precise movement control and various peripheral devices for the support of this robot.

PREM RANJAN

RAJ SINGH REPASWAL

SAUMYA GARG

PCE/EE/1

Chapter 1

INTRODUCTION

1.1 Embedded System

An embedded system is a computer system designed to do one or a few

dedicated and/or specific functions often with real-time computing constraints. It is

embedded as part of a complete device often including hardware and mechanical parts.

By contrast, a general-purpose computer, such as a personal computer (PC), is designed

to be flexible and to meet a wide range of end-user needs. Embedded systems control

many devices in common use today.

Embedded systems contain processing cores that are typically either

microcontrollers or digital signal processors (DSP). The key characteristic, however, is

being dedicated to handle a particular task. They may require very powerful processors

and extensive communication, for example air traffic control systems may usefully be

viewed as embedded, even though they involve mainframe computers and dedicated

regional and national networks between airports and radar sites (each radar probably

includes one or more embedded systems of its own).

Since the embedded system is dedicated to specific tasks, design engineers can

optimize it to reduce the size and cost of the product and increase the reliability and

performance. Some embedded systems are mass-produced, benefiting from economies of

scale.

Physically, embedded systems range from portable devices such as digital

watches and MP3 players, to large stationary installations like traffic lights, factory

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controllers, or the systems controlling nuclear power plants. Complexity varies from low,

with a single microcontroller chip, to very high with multiple units, peripherals and

networks mounted inside a large chassis or enclosure.

In general, "embedded system" is not a strictly definable term, as most systems

have some element of extensibility or programmability. For example, handheld

computers share some elements with embedded systems such as the operating systems

and microprocessors that power them, but they allow different applications to be loaded

and peripherals to be connected. Moreover, even systems that do not expose

programmability as a primary feature generally need to support software updates. On a

continuum from "general purpose" to "embedded", large application systems will have

subcomponents at most points even if the system as a whole is "designed to perform one

or a few dedicated functions", and is thus appropriate to call "embedded".

1.2 Variety of Embedded Systems

Embedded systems span all aspects of modern life and there are many examples

of their use.

Telecommunications systems employ numerous embedded systems

from telephone switches for the network to mobile phones at the end-user. Computer

networking uses dedicated routers and network bridges to route data.

Consumer electronics include personal digital assistants (PDAs), mp3 players,

mobile phones, videogame consoles, digital cameras, DVD players, GPS receivers,

and printers. Many household appliances, such as microwave ovens, washing

machines and dishwashers, are including embedded systems to provide flexibility,

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efficiency and features. Advanced HVAC systems use networked thermostats to more

accurately and efficiently control temperature that can change by time of day

and season. Home automation uses wired- and wireless-networking that can be used to

control lights, climate, security, audio/visual, surveillance, etc., all of which use

embedded devices for sensing and controlling.

Transportation systems from flight to automobiles increasingly use embedded

systems. New airplanes contain advanced avionics such as inertial guidance

systems and GPS receivers that also have considerable safety requirements. Various

electric motors — brushless DC motors, induction motors and DC motors — are using

electric/electronic motor controllers. Automobiles, electric vehicles, and hybrid

vehicles are increasingly using embedded systems to maximize efficiency and reduce

pollution. Other automotive safety systems include anti-lock braking

system (ABS), Electronic Stability Control (ESC/ESP), traction control (TCS) and

automatic four-wheel drive.

Medical equipment is continuing to advance with more embedded systems

for vital signs monitoring, electronic stethoscopes for amplifying sounds, and

various medical imaging(PET, SPECT, CT, MRI) for non-invasive internal inspections.

Embedded systems are especially suited for use in transportation, fire safety,

safety and security, medical applications and life critical systems as these systems can be

isolated from hacking and thus be more reliable. For fire safety, the systems can be

designed to have greater ability to handle higher temperatures and continue to operate. In

dealing with security, the embedded systems can be self-sufficient and be able to deal

with cut electrical and communication systems.

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In addition to commonly described embedded systems based on small computers,

new class of miniature wireless devices called motes are quickly gaining popularity as the

field of wireless sensor networking rises. Wireless sensor networking, WSN, makes use

of miniaturization made possible by advanced IC design to couple full wireless

subsystems to sophisticated sensors, enabling people and companies to measure a myriad

of things in the physical world and act on this information through IT monitoring and

control systems. These motes are completely self-contained, and will typically run off a

battery source for many years before the batteries need to be changed or charged.

1.3 Microcontrollers

A microcontroller (sometimes abbreviated µC, uC or MCU) is a small computer

on a single integrated circuit containing a processor core, memory, and

programmable input/output peripherals. Program memory in the form of NOR

flash or OTP ROM is also often included on chip, as well as a typically small amount

of RAM. Microcontrollers are designed for embedded applications, in contrast to

the microprocessors used in personal computers or other general purpose applications.

Microcontrollers are used in automatically controlled products and devices, such

as automobile engine control systems, implantable medical devices, remote controls,

office machines, appliances, power tools, toys and other embedded systems. By reducing

the size and cost compared to a design that uses a separate microprocessor, memory, and

input/output devices, microcontrollers make it economical to digitally control even more

devices and processes. Mixed signal microcontrollers are common, integrating analog

components needed to control non-digital electronic systems.

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Some microcontrollers may use four-bit words and operate at clock

rate frequencies as low as 4 kHz, for low power consumption (milliwatts or microwatts).

They will generally have the ability to retain functionality while waiting for an event such

as a button press or other interrupt; power consumption while sleeping (CPU clock and

most peripherals off) may be just Nano watts, making many of them well suited for long

lasting battery applications. Other microcontrollers may serve performance-critical roles,

where they may need to act more like a digital signal processor (DSP), with higher clock

speeds and power consumption.

1.4 Embedded Design of Microcontroller

A microcontroller can be considered a self-contained system with a processor,

memory and peripherals and can be used as an embedded system.[1]

The majority of

microcontrollers in use today are embedded in other machinery, such as automobiles,

telephones, appliances, and peripherals for computer systems. These are called embedded

systems. While some embedded systems are very sophisticated, many have minimal

requirements for memory and program length, with no operating system, and low

software complexity. Typical input and output devices include

switches, relays, solenoids, LEDs, small or custom LCD displays, radio frequency

devices, and sensors for data such as temperature, humidity, light level etc. Embedded

systems usually have no keyboard, screen, disks, printers, or other recognizable I/O

devices of a personal computer, and may lack human interaction devices of any kind.

PCE/EE/6

1.4.1 Interrupts

Microcontrollers must provide real time (predictable, though not necessarily fast)

response to events in the embedded system they are controlling. When certain events

occur, an interrupt system can signal the processor to suspend processing the current

instruction sequence and to begin an interrupt service routine (ISR, or "interrupt

handler"). The ISR will perform any processing required based on the source of the

interrupt before returning to the original instruction sequence. Possible interrupt sources

are device dependent, and often include events such as an internal timer overflow,

completing an analog to digital conversion, a logic level change on an input such as from

a button being pressed, and data received on a communication link. Where power

consumption is important as in battery operated devices, interrupts may also wake a

microcontroller from a low power sleep state where the processor is halted until required

to do something by a peripheral event.

1.4.2 Programs

Microcontroller programs must fit in the available on-chip program memory,

since it would be costly to provide a system with external, expandable, memory.

Compilers and assemblers are used to convert high-level language and assembler

language codes into a compact machine code for storage in the microcontroller's memory.

Depending on the device, the program memory may be permanent, read-only memory

that can only be programmed at the factory, or program memory may be field-alterable

flash or erasable read-only memory.

PCE/EE/7

1.4.3 Other microcontroller features

Microcontrollers usually contain from several to dozens of general purpose

input/output pins (GPIO). GPIO pins are software configurable to either an input or an

output state. When GPIO pins are configured to an input state, they are often used to read

sensors or external signals. Configured to the output state, GPIO pins can drive external

devices such as LEDs or motors.

Many embedded systems need to read sensors that produce analog signals. This is

the purpose of the analog-to-digital converter (ADC). Since processors are built to

interpret and process digital data, i.e. 1s and 0s, they are not able to do anything with the

analog signals that may be sent to it by a device. So the analog to digital converter is used

to convert the incoming data into a form that the processor can recognize. A less common

feature on some microcontrollers is a digital-to-analog converter (DAC) that allows the

processor to output analog signals or voltage levels.

In addition to the converters, many embedded microprocessors include a variety

of timers as well. One of the most common types of timers is the Programmable Interval

Timer (PIT). A PIT may either count down from some value to zero, or up to the capacity

of the count register, overflowing to zero. Once it reaches zero, it sends an interrupt to the

processor indicating that it has finished counting. This is useful for devices such as

thermostats, which periodically test the temperature around them to see if they need to

turn the air conditioner on, the heater on, etc.

PCE/EE/8

Time Processing Unit (TPU) is a sophisticated timer. In addition to counting

down, the TPU can detect input events, generate output events, and perform other useful

operations.

A dedicated Pulse Width Modulation (PWM) block makes it possible for the CPU

to control power converters, resistive loads, motors, etc., without using lots of CPU

resources in tight timer loops.

PCE/EE/9

Chapter 2

AUTONOMOUS ROBOT WITH ARM

2.1 Aims

The aim of this module was to work as a group to design and construct an

autonomous robot with arm.

We will be aiming to improve our knowledge of robotics as well as electronic

circuit design and construction.

We will be working as a group, and thus should improve our skills of working

together to achieve goals.

2.2 Objectives

Construct an autonomous robot with arm:

• That controlled with an infra-red remote.

• Which can move in any direction.

• Can lift any object of small weight (maxi. Capacity 50 gm.).

• Put the objects to another place.

• Rotate its arm at single place.

2.3 Project Restrictions:

• It should be robust and should have long life.

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• Must be no larger than 20x20x20cm in dimensions.

• Must be made within a budget of rupees 5000.

2.4 Individual Task

• IR Transmitter

• IR Receiver.

• Signal Processing

• Robot Movement

• Arm Movement

• Power Supply

• Body/Chassis.

• Motor Control.

2.4.1 IR Transmitter

By blinking an infrared LED, the signal becomes more unique and therefore more

discernible from other light sources. Even as intensity varies based on lighting, angle and

distance, the constant rate of blinking can be relied upon for recognition.

The rate of blinking should be sufficiently fast so that the signal can be quickly

recognized as being ―on‖. Since it takes a few blinks to detect the signal, delivering a

PCE/EE/11

message with a slow blink would be very time consuming. But, the rate of blinking

shouldn’t be so fast that expensive high-speed electronics are necessary.

If the device relies on a signal rates already in use, inexpensive and reliable mass-

produced parts will be available. It turns out that a popular consumer device, the remote

control, provides the robot hobbyist just that opportunity. A common rate for remote

control infrared transmissions is between 35 and 40 kHz (35,000 and 40,000 blinks per

second), and that’s exactly what this project is designed to generate.

Figure 2.1:- IR Transmitter

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2.4.2 IR Receiver

Figure 2.2:- IR Receiver

IR detectors are little microchips with a photocell that are tuned to listen to

infrared light. They are almost always used for remote control detection - every TV and

DVD player has one of these in the front to listen for the IR signal from the clicker.

Inside the remote control is a matching IR LED, which emits IR pulses to tell the TV to

turn on, off or change channels. IR light is not visible to the human eye, which means it

takes a little more work to test a setup.

IR detectors are specially filtered for Infrared light, they are not good at detecting

visible light. On the other hand, photocells are good at detecting yellow/green visible

light, not good at IR light

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IR detectors have a demodulator inside that looks for modulated IR at 38 KHz.

Just shining an IR LED won’t be detected, it has to be PWM blinking at 38KHz.

Photocells do not have any sort of demodulator and can detect any frequency (including

DC) within the response speed of the photocell (which is about 1KHz)

IR detectors are digital out - either they detect 38KHz IR signal and output low

(0V) or they do not detect any and output high (5V). Photocells act like resistors, the

resistance changes depending on how much light they are exposed.

2.4.3 Signal Processing

Typically microcontroller programs must fit in the available on-chip program

memory, since it would be costly to provide a system with external, expandable, memory.

Compilers and assemblers are used to convert high-level language and assembler

language codes into a compact machine code for storage in the microcontroller's memory.

Depending on the device, the program memory may be permanent, read-only memory

that can only be programmed at the factory, or program memory may be field-alterable

flash or erasable read-only memory.

Manufacturers have often produced special versions of their microcontrollers in

order to help the hardware and software development of the target system. Originally

these included EPROM versions that have a "window" on the top of the device through

which program memory can be erased by ultraviolet light, ready for reprogramming after

a programming ("burn") and test cycle. Since 1998, EPROM versions are rare and have

been replaced by EEPROM and flash, which are easier to use (can be erased

electronically) and cheaper to manufacture.

PCE/EE/14

Other versions may be available where the ROM is accessed as an external device

rather than as internal memory, however these are becoming increasingly rare due to the

widespread availability of cheap microcontroller programmers.

The use of field-programmable devices on a microcontroller may allow field

update of the firmware or permit late factory revisions to products that have been

assembled but not yet shipped. Programmable memory also reduces the lead time

required for deployment of a new product.

Where hundreds of thousands of identical devices are required, using parts

programmed at the time of manufacture can be an economical option. These "mask

programmed" parts have the program laid down in the same way as the logic of the chip,

at the same time.

A customizable microcontroller incorporates a block of digital logic that can be

personalized in order to provide additional processing capability, peripherals and

interfaces that are adapted to the requirements of the application. For example, the

AT91CAP from Atmel has a block of logic that can be customized during manufacturer

according to user requirements.

2.4.4 Robot Movement

2.4.4.1 Straight – Forward:-

Both wheels rotate at the same speed, but the right wheel rotates forward and the left

wheel rotates backward, so the robot turns to its left around its center. This makes a sharp turn in

place.

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Figure 2.3: - Straight – Forward

2.4.4.2 Straight – Backwards:-

Both wheels rotate forward at the same speed and the robot moves straight

backward.

Figure 2.4: - Straight – Backwards

2.4.4.3 Point Turn – Right:-

Both wheels rotate at the same speed, but the left wheel rotates forward and the

right wheel rotates backward, so the robot turns to its right around its center. This makes

a sharp turn in place.

Figure 2.5:- Point Turn – Right

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2.4.4.4 Point Turn – Left:-

Both wheels rotate at the same speed, but the right wheel rotates forward and the

left wheel rotates backward, so the robot turns to its left around its center. This makes a

sharp turn in place.

Figure 2.6:- Point Turn – Left

2.4.4.5 Swing Turn - Forward Right:-

The left wheel rotates forward and the right wheel does not move, so the robot

pivots around the right wheel as it turns forward. This makes a wider turn.

Figure 2.7:- Swing Turn - Forward Right

2.4.4.6 Swing Turn - Backward Right:-

The right wheel rotates backward and the left wheel does not move, so the robot pivots

around the left wheel as it turns backward. This makes a wider turn.

PCE/EE/17

Figure 2.8:- Swing Turn - Backward Right

2.4.4.7 Swing Turn - Forward Left:-

The right wheel rotates forward and the left wheel does not move, so the robot

pivots around the left wheel as it turns forward. This makes a wider turn.

Figure 2.9:- Swing Turn - Forward Left

2.4.4.8 Swing Turn - Backward Left:-

The left wheel rotates backward and the right wheel does not move, so the robot

pivots around the left wheel as it turns backward. This makes a wider turn.

Figure 2.10:- Swing Turn - Backward Left

PCE/EE/18

2.4.5 Arm Movement

The degrees of freedom, or DOF, are a very important term to understand. Each

degree of freedom is a joint on the arm, a place where it can bend or rotate or translate.

We can typically identify the number of degrees of freedom by the number of actuators

on the robot arm. Now this is very important - when building a robot arm we want as few

degrees of freedom allowed for our application, Because each degree requires a motor,

often an encoder, and exponentially complicated algorithms and cost.

Figure 2.11:- Arm Movement

2.4.6 Power Supply

This is a circuit which supplies the necessary voltages to all the circuits and systems on

the vehicle. The power source will be a 9V PP3 Battery. The 2 volt ―rails‖ initially

planned are 9V – to drive the motors, and 5V to drive the low power and logic circuitry.

The Battery is low soon. So, we use a transformer and diode rectifier circuit.

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2.4.7 Body/Chassis

Part # Description

1 The base of the robot, also the main PCB.

2 Front skid

3 Free Wheel, shaped as a pulley

4 Plastic pulley

5 Battery holder

6 Pipe clamp use to hold the motors

7 Ni-Cd 7.2V battery pack

8 1200 rpm 6V motor

Figure 2.12:- Chassis

It is clear that the drive train of this robot is differential type, meaning the two

rear wheels are responsible of moving the robot forward and backward, but are also used

to turn the robot in any required direction depending the difference of speed between the

right and left wheels.

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The first thing that need some explanation is the fact that there are only 2 wheels,

Well, while not being the best thing to do, a caster wheel can sometimes be replaced with

a skid, when the robot weight and size are not important, and when the robot is designed

for indoor environment, where the robot can move on relatively smooth surfaces, where

friction won’t be a serious problem.

2.4.8 Motor Control

The motor control circuit controls the speed of each motor therefore steering it

around the line. It is done by motor controller IC L293D.

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Chapter 3

CIRCUIT DIAGRAM

Figure 3.1 Circuit Diagram

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3.1 Microcontroller ATmega8

The ATmega8 is a low-power CMOS 8-bit microcontroller based

on the AVR RISC architecture. By executing powerful instructions in a

single clock cycle, the ATmega8 achieves throughputs approaching 1 MIPS

per MHz, allowing the system designed to optimize power consumption

versus processing speed.

3.1.1 Pin Configuration:

Figure 3.2: Pin Configuration

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Figure 3.3: Block Diagram of Microcontroller ATmega8

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3.1.2 Features

• High-performance, Low-power AVR® 8-bit Microcontroller

• Advanced RISC Architecture

– 130 Powerful Instructions – Most Single-clock Cycle Execution

– 32 x 8 General Purpose Working Registers

– Fully Static Operation

– Up to 16 MIPS Throughput at 16 MHz

– On-chip 2-cycle Multiplier

• High Endurance Non-volatile Memory segments

– 8K Bytes of In-System Self-programmable Flash program memory

– 512 Bytes EEPROM

– 1K Byte Internal SRAM

– Write/Erase Cycles: 10,000 Flash/100,000 EEPROM

– Data retention: 20 years at 85°C/100 years at 25°C(1)

– Optional Boot Code Section with Independent Lock Bits

In-System Programming by On-chip Boot Program

True Read-While-Write Operation

– Programming Lock for Software Security

• Peripheral Features

– Two 8-bit Timer/Counters with Separate Prescaler, one Compare Mode

– One 16-bit Timer/Counter with Separate Prescaler, Compare Mode, and Capture

Mode

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– Real Time Counter with Separate Oscillator

– Three PWM Channels

– 8-channel ADC in TQFP and QFN/MLF package

Eight Channels 10-bit Accuracy

– 6-channel ADC in PDIP package

Six Channels 10-bit Accuracy

– Byte-oriented Two-wire Serial Interface

– Programmable Serial USART

– Master/Slave SPI Serial Interface

– Programmable Watchdog Timer with Separate On-chip Oscillator

– On-chip Analog Comparator

• Special Microcontroller Features

– Power-on Reset and Programmable Brown-out Detection

– Internal Calibrated RC Oscillator

– External and Internal Interrupt Sources

– Five Sleep Modes: Idle, ADC Noise Reduction, Power-save, Power-down, and

Standby

• I/O and Packages

– 23 Programmable I/O Lines

– 28-lead PDIP, 32-lead TQFP, and 32-pad QFN/MLF

• Operating Voltages

– 2.7 - 5.5V (ATmega8L)

– 4.5 - 5.5V (ATmega8)

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• Speed Grades

– 0 - 8 MHz (ATmega8L)

– 0 - 16 MHz (ATmega8)

• Power Consumption at 4 Mhz, 3V, 25°C

– Active: 3.6 mA

– Idle Mode: 1.0 mA

– Power-down Mode: 0.5 μA

3.2 Motor Driver IC L293D

Figure 3.4:- Motor Driver IC L293D pin diagram

The Device is a monolithic integrated high voltage, high current four channel

driver designed to accept standard DTL or TTL logic levels and drive inductive loads

(such as relays solenoids, DC and stepping motors) and switching power transistors.

PCE/EE/27

To simplify use as two bridges each pair of channels is equipped with an enable input. A

separate supply input is provided for the logic, allowing operation at a lower voltage and

internal clamp diodes are included.

This device is suitable for use in switching applications at frequencies up to 5

kHz.

The L293D is assembled in a 16 lead plastic package which has 4 center pins

connected together and used for heat sinking The L293DD is assembled in a 20 lead

surface mount which has 8 center pins connected together and used for heat sinking.

Figure 3.5:- Block Diagram of L293D

PCE/EE/28

3.3 Crystal Oscillator

A crystal oscillator is an electronic oscillator circuit that uses the

mechanical resonance of a vibrating crystal of piezoelectric material to create an

electrical signal with a very precise frequency. This frequency is commonly used to keep

track of time (as in quartz wristwatches), to provide a stable clock

signal for digital integrated circuits, and to stabilize frequencies for radio

transmitters and receivers. The most common type of piezoelectric resonator used is

the quartz crystal, so oscillator circuits designed around them became known as "crystal

oscillators."

Quartz crystals are manufactured for frequencies from a few tens of kilohertz to

tens of megahertz. More than two billion (2×109) crystals are manufactured annually.

Most are used for consumer devices such as wristwatches, clocks, radios, computers,

and cellphones. Quartz crystals are also found inside test and measurement equipment,

such as counters, signal generators, and oscilloscopes.

3.4 7805 Voltage Regulator IC

7805 is a voltage regulator integrated circuit. It is a member of 78xx series of

fixed linear voltage regulator ICs. The voltage source in a circuit may have fluctuations

and would not give the fixed voltage output. The voltage regulator IC maintains the

output voltage at a constant value. The xx in 78xx indicates the fixed output voltage it is

designed to provide. 7805 provides +5V regulated power supply. Capacitors of suitable

values can be connected at input and output pins depending upon the respective voltage

levels.

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Figure 3.6:- 7805 Voltage Regulator IC

3.5 Stepper Motor

A stepper motor (or step motor) is a brushless DC electric motor that divides a

full rotation into a number of equal steps. The motor's position can then be commanded

to move and hold at one of these steps without any feedback sensor (an open-loop

controller), as long as the motor is carefully sized to the application.

The stepper motor is an electromagnetic device that converts digital pulses into

mechanical shaft rotation. Advantages of step motors are low cost, high reliability, high

torque at low speeds and a simple, rugged construction that operates in almost any

environment. The main disadvantages in using a stepper motor is the resonance effect

often exhibited at low speeds and decreasing torque with increasing speed.

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Figure 3.7:- Stepper Motor

PCE/EE/31

3.6 Infra-red Remote

A remote control is a component of an electronics device, most commonly a

television set, DVD player and home theater systems originally used for operating the

television device wirelessly from a short line-of-sight distance. Remote control has

continually evolved and advanced over recent years to include Bluetooth connectivity,

motion sensor enabled capabilities and voice control.

The main remote control technology used in the home is infrared. The signal

between a remote control handset and the device it is controlling are infrared pulses,

which are invisible to the human eye. The transmitter in the remote control handset sends

out a pulse of infrared light when a button is pressed on the handset. A transmitter is

often a light emitting diode (LED) which is built into the pointing end of the remote

control handset. The infrared light pulse represents a binary code that corresponds to a

certain command, such as (power on). The receiver passes the code to a microprocessor,

which decodes it and carries out the command.

Figure 3.8: Remote

PCE/EE/32

3.7 Power Supply

There are many types of power supply. Most are designed to convert high voltage

AC mains electricity to a suitable low voltage supply for electronics circuits and other

devices. A power supply can by broken down into a series of blocks, each of which

performs a particular function.

For example a 5V regulated supply:

Each of the blocks is described in more detail below:-

Transformer - steps down high voltage AC mains to low voltage AC.

Rectifier - converts AC to DC, but the DC output is varying.

Smoothing - smooth the DC from varying greatly to a small ripple.

Regulator - eliminates ripple by setting DC output to a fixed voltage.

Figure 3.9: Circuit Diagram of regulated power Supply

PCE/EE/33

3.7.1 Transformer

Transformers convert AC electricity from one voltage to another with little loss of

power. Transformers work only with AC and this is one of the reasons why mains

electricity is AC.

Step-up transformers increase voltage, step-down transformers reduce voltage. Most

power supplies use a step-down transformer to reduce the dangerously high mains

voltage (230V in UK) to a safer low voltage.

The input coil is called the primary and the output coil is called the secondary. There

is no electrical connection between the two coils, instead they are linked by an alternating

magnetic field created in the soft-iron core of the transformer. The two lines in the middle

of the circuit symbol represent the core.

Transformers waste very little power so the power out is (almost) equal to the power

in. Note that as voltage is stepped down current is stepped up.

The ratio of the number of turns on each coil, called the turns ratio, determines the

ratio of the voltages. A step-down transformer has a large number of turns on its primary

(input) coil which is connected to the high voltage mains supply, and a small number of

turns on its secondary (output) coil to give a low output voltage.

turns ratio = Vp

= Np

and power out = power in

Vs Ns Vs × Is = Vp × Ip

Vp = primary (input) voltage

Np = number of turns on primary

coil

Ip = primary (input) current

Vs = secondary (output) voltage

Ns = number of turns on secondary

coil

Is = secondary (output) current

Rectifier

PCE/EE/34

There are several ways of connecting diodes to make a rectifier to

convert AC to DC. The bridge rectifier is the most important and it produces

full-wave varying DC. A full-wave rectifier can also be made from just two

diodes if a center-tap transformer is used, but this method is rarely used now

that diodes are cheaper. A single diode can be used as a rectifier but it only uses

the positive (+) parts of the AC wave to produce half-wave varying DC.

3.7.2 Bridge rectifier

A bridge rectifier can be made using four individual diodes, but it is also

available in special packages containing the four diodes required. It is called a

full-wave rectifier because it uses all the AC wave (both positive and negative

sections). 1.4V is used up in the bridge rectifier because each diode uses 0.7V

when conducting and there are always two diodes conducting, as shown in the

diagram below. Bridge rectifiers are rated by the maximum current they can

pass and the maximum reverse voltage they can withstand (this must be at least

three times the supply RMS voltage so the rectifier can withstand the peak

voltages). Please see the Diodes page for more details, including pictures of

bridge rectifiers.

PCE/EE/35

Figure 3.10 Bridge rectifier

Alternate pairs of diodes conduct, changing over the connections so the

alternating directions of AC are converted to the one direction of DC

Figure 3.11: Output: full-wave varying DC

(using all the AC wave)

3.7.3 Smoothing

Smoothing is performed by a large value electrolytic capacitor connected across

the DC supply to act as a reservoir, supplying current to the output when the varying DC

voltage from the rectifier is falling. The diagram shows the unsmoothed varying DC

PCE/EE/36

(dotted line) and the smoothed DC (solid line). The capacitor charges quickly near the

peak of the varying DC, and then discharges as it supplies current to the output.

Figure 3.12: Smoothing

Note that smoothing significantly increases the average DC voltage to almost the

peak value (1.4 × RMS value). For example 6V RMS AC is rectified to full wave DC of

about 4.6V RMS (1.4V is lost in the bridge rectifier), with smoothing this increases to

almost the peak value giving 1.4 × 4.6 = 6.4V smooth DC.

Smoothing is not perfect due to the capacitor voltage falling a little as it

discharges, giving a small ripple voltage. For many circuits a ripple which is 10% of the

supply voltage is satisfactory and the equation below gives the required value for the

smoothing capacitor. A larger capacitor will give fewer ripples. The capacitor value must

be doubled when smoothing half-wave DC.

Smoothing capacitor for 10% ripple, C = 5 × Io

Vs × f

Io = output current from the supply

Vs = supply voltage (peak value of unsmoothed DC)

f = frequency of the AC supply (50Hz in UK)

PCE/EE/37

3.8 Resistors

This is the most common component in electronics. It is used mainly

to control current and voltage within the circuit. We can identify a simple

resistor by its simple cigar shape with a wire lead coming out of each end. It

uses a system of color coded bands to identify the value of the component

(measured in Ohms) A surface mount resistor is in fact mere millimeters in

size but performs the same function as its bigger brother, the simple resistor.

A potentiometer is a variable resistor. It lets you vary the resistance with a

dial or sliding control in order to alter current or voltage on the fly. This is

opposed to the ―fixed‖ simple resistors.

3.9 Condensers/Capacitors

Capacitors, or "caps", vary in size and shape - from a small surface

mount model up to a huge electric motor cap the size of a paint can. It

storages electrical energy in the form of electrostatic charge. The size of a

capacitor generally determines how much charge it can store. A small

surface mount or ceramic cap will only hold a minuscule charge. A

cylindrical electrolytic cap will store a much larger charge. Some of the

large electrolytic caps can store enough charge to kill a person. Another

type, called Tantalum Capacitors, store a larger charge in a smaller package.

PCE/EE/38

3.10 Inductors

We remember from science class that adding electrical current to a

coil of wire produces a magnetic field around itself. This is how the inductor

works. It is charged with a magnetic field and when that field collapses it

produces current in the opposite direction. Inductors are used in Alternating

Current circuits to oppose changes in the existing current. Most inductors

can be identified by the ―coil" appearance. Others actually look like a

resistor but are usually green in color.

3.11 Diodes

Diodes are basically a one-way valve for electrical current. They let it

flow in one direction (from positive to negative) and not in the other

direction. This is used to perform rectification or conversion of AC current

to DC by clipping off the negative portion of a AC waveform. The diode

terminals are cathode and anode and the arrow inside the diode symbol

points towards the cathode, indicating current flow in that direction when the

diode is forward biased and conducting current. Most diodes are similar in

appearance to a resistor and will have a painted line on one end showing the

direction or flow (white side is negative). If the negative side is on the

negative end of the circuit, current will flow. If the negative is on the

positive side of the circuit no current will flow.

PCE/EE/39

3.12 Transistors

The transistor performs two basic functions. 1) It acts as a switch

turning current on and off. 2) It acts as a amplifier. This makes an output

signal that is a magnified version of the input signal.

Transistors come in several sizes depending on their application. It

can be a big power transistor such as is used in power amplifiers in your

stereo, down to a surface mount (SMT) and even down to .5 microns wide

(I.E.: Mucho Small!) such as in a microprocessor or Integrated Circuit.

3.13 ICs (Integrated Circuits)

Integrated Circuits, or ICs, are complex circuits inside one simple

package. Silicon and metals are used to simulate resistors, capacitors,

transistors, etc. It is a space saving miracle. These components come in a

wide variety of packages and sizes. You can tell them by their "monolithic

shape" that has a ton of "pins" coming out of them. Their applications are as

varied as their packages. It can be a simple timer, to a complex logic circuit,

or even a microcontroller (microprocessor with a few added functions) with

erasable memory built inside.

3. 14 Microprocessors (MPUs)

Microprocessors and other large scale ICs are very complex ICs. At

their core is the transistor which provides the logic for computers, cars, TVs

PCE/EE/40

and just about everything else electronic. Packages are becoming smaller

and smaller as companies are learning new tricks to make the transistors

ever tinier.

PCE/EE/41

Chapter 4

CODING

; ---------==========----------==========---------=========---------

; Autonomous Robot with Arm

; ---------==========----------==========---------=========---------

DSEG ; This is internal data memory

ORG 20H ; Bit adressable memory

FLAGS: DS 1

CONTROL BIT FLAGS.0 ; toggles with every new keystroke

NEW BIT FLAGS.1 ; Bit set when a new command has been received

COMMAND: DS 1 ; Received command byte

SUBAD: DS 1 ; Device subaddress

TOGGLE: DS 1 ;Toggle every bit

ANS: DS 1 ;

ADDR: DS 1

STACK: DS 1 ; Stack begins here

CSEG ; Code begins here

;---------==========----------==========---------=========---------

PCE/EE/42

; PROCESSOR INTERRUPT AND RESET VECTORS

;---------==========----------==========---------=========---------

ORG 00H ; Reset

JMP MAIN

ORG 0003H ; External Interrupt0

JMP RECEIVE

; ---------==========----------==========---------=========---------

; Interrupt 0 routine

; ---------==========----------==========---------=========---------

RECEIVE:

cpl p3.7

MOV 2,#255 ; Time Loop (3/4 bit time)

DJNZ 2,$ ; Waste Time to sync second bit

MOV 2,#255 ; Time Loop (3/4 bit time)

Djnz 2,$ ; Waste Time to sync second bit

Mov 2,#145 ; Time Loop (3/4 bit time)

Djnz 2,$ ; Waste Time to sync second bit

PCE/EE/43

clr a

mov r6,#07h

AJMP ASZ

ZXC1: MOV A,SUBAD

CJNE A,#00H,ANSS

AJMP ASZ

ASZ: MOV A,ADDR

ANL A,#20H

MOV TOGGLE,A

CJNE A,ANS,ANSS

AJMP WAR

ANSS: JMP ANS1

WAR:

;!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!

MOV A,COMMAND

;-------------------------------------------

PCE/EE/44

MOV R0,A

XRL A,#01H

JNZ CH1

CPL OP1

AJMP GO

CH1: MOV A,R0

XRL A,#02H

JNZ CH2

CPL OP2

AJMP GO

CH2: MOV A,R0

XRL A,#03H

JNZ CH3

CPL OP3

AJMP GO

CH3: MOV A,R0

XRL A,#04H

PCE/EE/45

JNZ CH4

CPL OP4

AJMP GO

CH4: MOV A,R0

XRL A,#05H

JNZ CH5

CPL OP5

AJMP GO

CH5: MOV A,R0

XRL A,#06H

JNZ CH6

CPL OP6

AJMP GO

CH6: MOV A,R0

XRL A,#0CH

JNZ go

MOV OUTPUT,#0FFH

PCE/EE/46

AJMP GO

GO:

;***********************************************************

MOV ANS,TOGGLE

MOV A,ANS

CPL ACC.5

MOV ANS,A

SETB NEW ; Set flag to indicate the new command

;################################################################

ANS1:

RETI

; ---------==========----------==========---------=========---------

; Main routine. Program execution starts here.

; ---------==========----------==========---------=========---------

MAIN:

MOV SP,#60H

PCE/EE/47

MOV OUTPUT,#0FFH

SETB EX0 ; Enable external Interrupt0

CLR IT0 ; triggered by a high to low transition

SETB EA

MOV ANS,#00H ;clear temp toggle bit

CLR NEW

LOO:

JNB NEW,LOO

CLR NEW

AJMP LOO

END

PCE/EE/48

Chapter 5

CONCLUSION

From the construction of this prototype, we can arrive at several conclusions for the final

Prototype:

The robot can move in any direction.

It is fully controlled by remote.

It can pick up light objects from a place and put them to another place.

It can also put objects to a height and put down them from the height also.

It takes power supply of 220V, 1-phase A.C.

It can pick a maximum weight of 50 grams.

PCE/EE/49

Chapter 6

REFERENCES

http://www.kpsec.freeuk.com/powersup.htm

http://en.wikipedia.org/wiki/Microcontroller

http://en.wikipedia.org/wiki/Embedded_system

www.ieee.com

www.NASAexplores.com

www.robotics.com

http://en.wikipedia.org/wiki/Stepper_motor

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

http://www.robotc.net/support/nxt/MindstormsWebHelp/index.htm#page=robot_algebra/

robot_movements/Robot%20Movements.htm