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Page 1: Neobot Thesis

Project N.E.O.BOT

DREAM INSTITUTE OF TECHNOLOGY Page 1

Page 2: Neobot Thesis

Project N.E.O.BOT

PROJECT N.E.O.BOT

(Negotiating Edge and Overcoming roBOT)

BY

1. SAIKAT ROY (G.L)…………..(EC/08/30)

2. AYAN MAJUMDER…………..(EC/08/11)

3. RANIT MAJUMDER…………..(EC/08/29)

4. SAURAV DAS………………….(EC/08/33)

5. SUMIT MAHATO…………….(EC/08/46)

ELECTRONICS AND COMMUNICATION ENGINEERING

DEPARTMENT

Submitted in fulfillment of the requirements of the degree of

Bachelor of Technology

TO

DREAM INSTITUTE OF TECHNOLOGY

PO: Nahazari, VILL: Samali, PS: Bishnupur . 24Pgns(S) Kolkata-700104

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C E R T I F I C A T E

This is to certify that the dissertation entitled “PROJECT N.E.O.BOT”

submitted by

1. SAIKAT ROY (G.L)…………..(EC/08/30)

2. AYAN MAJUMDER…………..(EC/08/11)

3. RANIT MAJUMDER………….(EC/08/29)

4. SAURAV DAS………………….(EC/08/33)

5. SUMIT MAHATO……………..(EC/08/46)

in partial fulfillment for the award of the degree of Bachelor of Technology

in Electronics and Communication Engineering Department is a bonafide

record of the work carried out by them under my supervision.

The matter embodied in this dissertation, to the best of my knowledge has

not been submitted for the award of any degree or diploma elsewhere.

Date:

ABHISHEK MAZUMDAR

Project Guide

D ream Institute Of

Technology Kolkata -

700104

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INDEX

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ACKNOWLEDGEMENT

Apart from the individual efforts , the success of any project depends largely on the

encouragement and guidelines of many others. We take this opportunity to express

gratitude. to the people who have been instrumental in the successful completion of

this project.

I express thanks to Dr. Dipankar Sarkar, our Director And

Mr. Abhishek Mazumdar our mentor, of DREAM INSTITUTE OF

TECHNOLOGY. Without their encouragement and guidance this project would not

have materialized.

The guidance and support received from all the members who contributed and who

are contributing to this project, was vital for the success of the project. We are

grateful for their constant support and help. I also extend my heartfelt thanks to my

family and well wishers.

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SYNOPSIS

In the world of automation, simulation of the human mind using artificial

intelligence has strategic importance. It is worth noting that large scale industry

primarily depends on automatic processes. Advantages such as perfection in

design, bulk production and reduction in human overhead drive the need to

automate a certain process. A work is best done by a human because man has the

most superior brain that can be trained and made to adapt varying situations. Such

a dynamic environment is difficult to attain in a system of mechanical or electrical

robots. Artificial intelligence (AI) implants a brain into these lifeless entities.

Implementation of an AI based system demands flexibility, adaptability and

changeability.

A microcontroller offers all the three requirements. A microcontroller with its flash

memory provides ample space for the learning algorithm to operate.

Microcontrollers such as the PIC and Basic Stamp offers certain added features

that help the process of implementation. The available IDEs and simulation tools

come as a package that allows real time simulation even without actually

implementing the design. Statistical tools may then be used to analyze these results

and form an opinion about the system design. These added features go on to make

microcontrollers the best hardware to implement artificially intelligent systems. In

this project we are going to build an autonomous robot that will prevent itself from

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falling off the edge. The NEOBOT operates in 2 modes ,namely 1)autonomous and

2)manual.

The user can switch to any one of the above mode with the help of a mode selector

switch integrated on the robot body. In autonomous mode the NEOBOT detects

edges in its path and can take intelligent decisions to avoid it. Under manual mode

the user is provided with a remote through which user can control the motion in 4

directions( forward ,backward, left right) and also control the speed of the robot in

3 modes.

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INTRODUCTION

Autonomous robots are robots which can perform desired tasks in unstructured

environments without continuous human guidance. Many kinds of robots have

some degree of autonomy. Different robots can be autonomous in different ways.

A high degree of autonomy is particularly desirable in fields such as space

exploration, cleaning floors, mowing lawns, and waste water treatment.

One important area of robotics research is to enable the robot to cope with its

environment whether this be on land, underwater, in the air, underground, or in

space.

A fully autonomous robot has the ability to

Gain information about the environment.

Work for an extended period without human intervention.

Move either all or part of itself throughout its operating environment without

human assistance.

Avoid situations that are harmful to people, property, or itself unless those

are part of its design specifications.

An autonomous robot may also learn or gain new capabilities like adjusting

strategies for accomplishing its task(s) or adapting to changing surroundings.

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Autonomous robots still require regular maintenance, as do other machines.

Examples of progress towards commercial autonomous robots

Self-maintenance

Self maintenance is based on "proprioception", or sensing one's own internal

status.

Common proprioceptive sensors are

Thermal

Hall Effect

Optical

Contact

Sensing the environment

Exteroception is sensing things about the environment. Autonomous robots must

have a range of environmental sensors to perform their task and stay out of trouble.

Common exteroceptive sensors are

Electromagnetic spectrum

Sound

Touch

Chemical sensors (smell, odor)

Temperature

Range to things in the environment

Attitude (Inclination)

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Task performance

The next step in autonomous behavior is to actually perform a physical task.

The next level of autonomous task performance requires a robot to perform

conditional tasks. For instance, security robots can be programmed to detect

intruders and respond in a particular way depending upon where the intruder is.

Outdoor autonomous position-sensing and navigation

Outdoor autonomy is most easily achieved in the air, since obstacles are

rare. Cruise missiles are rather dangerous highly autonomous robots.

Automation in our project

The automation of NEOBOT is mainly implemented by the Atmega8

microcontroller. The robot senses the environment with the help of the sensors and

the status of the sensors are continuously interpreted by the microcontroller to take

intelligent decisions concerning the motion of the robot. In any case failure of

automation is overcome by the implementation of the remote control module

which allow the user to retrieve the robot from any type of environmental

hindrance. Based on suitable environment the NEOBOT is an autonomous robot

and can move on its own without any human aid.

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CAUSE OF CHOOSING THIS PROJCET

The main reason for choosing this project is the fact that modern day Robotics has

been progressing at a very fast rate and for electronics engineer like us it presents a

great opportunity and prospect to work in this field and develop something that in

future will be beneficial to the whole human kind.

This robot is a prototype for eliminating dependency of industries on

labourers. Since it is an autonomous robot it can be used as automated

carriers. Whatever may be the functionality an autonomous robot always

eliminate human dependency.

Since it can detect edges with moderate accuracy there is always a provision

for using it at a medium of transport in hilly regions. It can reduce accidents

prone to human errors.

Therefore through this projects we are basically trying to solve the above

mentioned problem by building an autonomous with an inbuilt memory

which can ideally sense edges and avoid them automatically thereby

reducing human intervention.

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BASIC BLOCK DIAGRAM OF NEOBOT

We have divided our project into 5 basic modules. They are

Power supply Control unit Sensing unit Motor and motor controllers.

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DC motor

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POWER SUPPLY UNIT

This unit supplies power to to the complete robotic module. The power supply

consists of :-

9 v dc battery

2pin Power Supply Connector .

A diode ( IN4007)

One capacitor (470 µF, 25 V )

Regulator IC LM7805

.1µF ceramic capacitor

1 push button ON/OFF switch

1 K resistor

3mm red LED (indicator)

Working:-

The input from the 9v dc battery is fed to the power supply connector followed by

a reverse polarity protection diode(IN4007). A 5v constant power supply is

obtained by using the voltage regulator IC 7805. The capacitors ( 470µF and

0.1µF)are used as filtering capacitors. The 1k resistor is used for protecting the

3mm red LED which is used as a power supply indicator.

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LM7805

v

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Ripple factor:-The most common meaning of ripple in electrical science is the

small unwanted residual periodic variation of the direct current (dc) output of a

power supply which has been derived from an alternating current (ac) source. This

ripple is due to incomplete suppression of the alternating waveform within the

power supply. Ripple factor (γ) may be defined as the ratio of the root mean

square (rms) value of the ripple voltage to the absolute value of the dc component

of the output voltage, usually expressed as a percentage.

γ = {rms value of alternating components of load current( or voltage)} ∕

{average value of load current (or voltage)}

The ripple voltage is very large in this situation; the peak-to-peak ripple voltage is

equal to the peak ac voltage. The large smoothing capacitor  acts as a reservoir.

After a peak in output voltage the capacitor (C) supplies the current to the load (R)

and continues to do so until the capacitor voltage has fallen to the value of the now

rising next half-cycle of rectified voltage. At that point the rectifiers turn on again

and deliver current to the reservoir until peak voltage is again reached. If the time

constant, CR, is large in comparison to the period of the ac waveform, then a

reasonable accurate approximation can be made by assuming that the capacitor

voltage falls linearly..

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Fig: - Ripple voltage from a full-wave rectifier, before and after the application of a smoothing capacitor

The 9v dc is used to power:-

The 2 IR sensors

The microcontroller board.

The chassis containing the dc motors and motor controller circuits.

POWER DISTRIBUTION:

The microcontroller board and the sensors solely require 5v dc supply while the

motors and motor controller circuits requires both 9v and 5v dc supply

LM7805

The 7805 voltage regulators employ built-in current limiting, thermal shutdown,

and safe-operating area protection which makes them virtually immune to damage

from output overloads. 7805 is a three-terminal positive voltage regulator.With

adequate heatsinking, it can deliver in excess of 0.5A output current. Typical

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applications would include local (on-card) regulators which can eliminate the noise

and degraded performance associated with single-point regulation.

7805 regulator comes from the 78xx family of self-contained fixed linear voltage

regulator integrated circuits. The 78xx family is a very popular choice for many

electronic circuits which require a regulated power supply, due to their ease of use

and relative cheapness. When specifying individual ICs within this family, the xx

is replaced with a two-digit number, which indicates the output voltage the

particular device is designed to provide (for example, the 7805 voltage regulator

has a 5 volt output, while the 7812 produces 12 volts). The 78xx line are positive

voltage regulators, meaning that they are designed to produce a voltage that is

positive relative to a common ground. There is a related line of 79xx devices which

are complementary negative voltage regulators. 78xx and 79xx ICs can be used in

combination to provide both positive and negative supply voltages in the same

circuit, if necessary.

7805 ICs have three terminals and are most commonly found in the TO220 form

factor, although smaller surface-mount and larger TO3 packages are also available

from some manufacturers. These devices typically support an input voltage which

can be anywhere from a couple of volts over the intended output voltage, up to a

maximum of 35 or 40 volts, and can typically provide up to around 1 or 1.5 amps

of current (though smaller or larger packages may have a lower or higher current

rating).

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 Pin Diagram: 

Pin Description: 

Pin

No

Function Name

1 Input voltage (5V-18V) Input

2 Ground (0V) Ground

3 Regulated output; 5V (4.8V-5.2V) Output

Advantages

78xx series ICs do not require additional components to provide a constant,

regulated source of power, making them easy to use, as well as economical and

efficient uses of space. Other voltage regulators may require additional

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components to set the output voltage level, or to assist in the regulation process.

Some other designs (such as a switching power supply) may need substantial

engineering expertise to implement.

78xx series ICs have built-in protection against a circuit drawing too much

power. They have protection against overheating and short-circuits, making

them quite robust in most applications. In some cases, the current-limiting

features of the 78xx devices can provide protection not only for the 78xx itself,

but also for other parts of the circuit.

Disadvantages

The input voltage must always be higher than the output voltage by some

minimum amount (typically 2 volts). This can make these devices unsuitable

for powering some devices from certain types of power sources (for example,

powering a circuit that requires 5 volts using 6-volt batteries will not work

using a 7805).

As they are based on a linear regulator design, the input current required is

always the same as the output current. As the input voltage must always be

higher than the output voltage, this means that the total power (voltage

multiplied by current) going into the 78xx will be more than the output power

provided. The extra input power is dissipated as heat. This means both that for

some applications an adequate heat sink must be provided, and also that a (often

substantial) portion of the input power is wasted during the process, rendering

them less efficient than some other types of power supplies. When the input

voltage is significantly higher than the regulated output voltage (for example,

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powering a 7805 using a 24 volt power source), this inefficiency can be a

significant issue.

Even in larger packages, 78xx integrated circuits cannot supply as much

power as many designs which use discrete components, and are generally

inappropriate for applications requiring more than a few amps of current.

CONTROL UNIT

AVR MICROCONTROLLER: ATMEGA8

The AVR core combines a rich instruction set with 32 general purpose working

registers. All the 32 registers are directly connected to the Arithmetic Logic Unit

(ALU), allowing two independent registers to be accessed in one single instruction

executed in one clock cycle. The resulting architecture is more code efficient while

achieving throughputs up to ten times faster than conventional CISC

microcontrollers

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The device is manufactured using Atmel‟s high density non-volatile memory

technology. The Flash Program memory can be reprogrammed In-System through

an SPI serial interface, by a conventional non-volatile memory programmer, or by

an On-chip boot program running on the AVR core. The boot program can use any

interface to download the application program in the Application Flash memory.

Software in the Boot Flash Section will continue to run while the Application Flash

Section is updated, providing true Read-While-Write operation. By combining an

8-bit RISC CPU with In-System Self-Programmable Flash on a monolithic chip,

the Atmel ATmega8 is a powerful microcontroller that provides a highly-flexible

and cost-effective solution to many embedded control applications

The ATmega8 provides 8K bytes of In-System Programmable Flash with Read-

While-Write capabilities, 512 bytes of EEPROM, 1K byte of SRAM, 23 general

purpose I/O lines, 32 general purpose working registers, three flexible

Timer/Counters with compare modes, internal and external interrupts, a serial

programmable USART, a byte oriented Two-wire Serial Interface, a 6-channel

ADC (eight channels in TQFP and QFN/MLF packages) with 10-bit accuracy, a

programmable Watchdog Timer with Internal Oscillator, an SPI serial port, and

five software selectable power saving modes. The Idle mode stops the CPU while

allowing the SRAM, Timer/Counters, SPI port, and interrupt system to continue

functioning. The Power down mode saves the register contents but freezes the

Oscillator, disabling all other chip functions until the next Interrupt or Hardware

Reset. In Power-save mode, the asynchronous timer continues to run, allowing the

user to maintain a timer base while the rest of the device is sleeping. The ADC

Noise Reduction mode stops the CPU and all I/O modules except asynchronous

timer and ADC, to minimize switching noise during ADC conversions. In Standby

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mode, the crystal/resonator Oscillator is running while the rest of the device is

sleeping. This allows very fast start-up combined with low-power consumption.

6.1 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

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

Real Time Counter with Separate Oscillator

Three PWM Channels

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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

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)

Power Consumption at 4 Mhz, 3V, 25°C

Active: 3.6 mA

Idle Mode: 1.0 mA

Power-down Mode: 0.5 μA

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PIN CONFIGURATION OF ATmega8

PIN DESCRIPTION:

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VCC Digital supply voltage.

GND Ground.

Port B (PB7..PB0) XTAL1/XTAL2/TOSC1/ TOSC2 Port B is an 8-bit bi-

directional I/O port with internal pull-up Resistors (selected for each bit). The Port

B output buffers have symmetrical drive characteristics with both high sink and

source capability. As inputs, Port B pins that are externally pulled low will source

current if the pull-up resistors are activated. The Port B pins are tri-stated when a

reset condition becomes active, even if the clock is not running. Depending on the

clock selection fuse settings, PB6 can be used as input to the inverting Oscillator

amplifier and input to the internal clock operating circuit. Depending on the clock

selection fuse settings, PB7 can be used as output from the inverting Oscillator

amplifier. If the Internal Calibrated RC Oscillator is used as chip clock source,

PB7..6 is used as TOSC2..1 input for the Asynchronous Timer/Counter2 if the AS2

bit in ASSR is set.

Port C (PC5..PC0) Port C is an 7-bit bi-directional I/O port with internal pull-up

resistors (selected for each bit). The Port C output buffers have symmetrical drive

characteristics with both high sink and source capability. As inputs, Port C pins

that are externally pulled low will source current if the pull-up resistors are

activated. The Port C pins are tri-stated when a reset condition becomes active,

even if the clock is not running.

PC6/RESET If the RSTDISBL Fuse is programmed, PC6 is used as an I/O pin.

The electrical characteristics of PC6 differ from those of the other pins of Port C. If

the RSTDISBL Fuse is unprogrammed, PC6 is used as a Reset input. A low level

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on this pin for longer than the minimum pulse length will generate a Reset, even if

the clock is not running. Shorter pulses are not guaranteed to generate a Reset.

Port D (PD7..PD0) Port D is an 8-bit bi-directional I/O port with internal pull-up

resistors selected for each bit). The Port D output buffers have symmetrical drive

characteristics with both high sink and source capability. As inputs, Port D pins

that are externally pulled low will source current if the pull-up resistors are

activated. The Port D pins are tri-stated when a reset condition becomes active,

even if the clock is not running.

RESET Reset input. A low level on this pin for longer than the minimum pulse

length will generate a reset, even if the clock is not running. Shorter pulses are not

guaranteed to generate a reset.

AVCC AVCC is the supply voltage pin for the A/D Converter, Port C (3..0), and

ADC It should be externally connected to VCC, even if the ADC is not used. If the

ADC is used, it should be connected to VCC through a low-pass filter. Note that

Port C (5..4) use digital supply voltage, VCC.

AREF AREF is the analog reference pin for the A/D Converter.

ADC7..6 (TQFP and QFN/MLF) In the TQFP and QFN/MLF package,

ADC7..6 serve as analog inputs to the A/D converter. These pins are powered

from the analog supply and serve as 10-bit. ADC channels

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ARCHITECTURAL VIEW

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TYPICAL CHARACTERISTICS OF ATMEGA8

A. Idle Supply Current vs. VCC

B. I/O Pin Source Current vs. Output Voltage (Internal RC Oscillator, 8 MHz) (VCC = 5V)

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L293D MOTOR DRIVER

The L293 and L293D are quadruple high-current half-H drivers. The L293 is

designed to provide bidirectional drive currents of up to 1 A at voltages from 4.5 V

to 36 V. The L293D is designed to provide bidirectional drive currents of up to

600-mA at voltages from 4.5 V to 36 V. Both devices are designed to drive

inductive loads such as relays, solenoids, dc and bipolar stepping motors, as well

as other high-current/high-voltage loads in positive-supply applications. All inputs

are TTL compatible. Each output is a complete totem-pole drive circuit, with a

Darlington transistor sink and a pseudo- Darlington source. Drivers are enabled in

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pairs, with drivers 1 and 2 enabled by 1,2EN and drivers 3 and 4 enabled by

3,4EN. When an enable input is high, the associated drivers are enabled, and their

outputs are active and in phase with their inputs. When the enable input is low,

those drivers are disabled, and their outputs are off and in the high-impedance

state. With the proper data inputs, each pair of drivers forms a full-H (or bridge)

reversible drive suitable for solenoid or motor applications. On the L293, external

high-speed output clamp diodes should be used for inductive transient suppression.

A VCC1 terminal, separate from VCC2, is provided for the logic inputs to

minimize device power dissipation. The L293and L293D are characterized for

operation from 0°C to 70°C.

PIN DIAGRAM OF IC L293D

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BLOCK DIAGRAM OF L293D

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ARCHITECTURAL VIEW OF IC L293D

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WORKING OF SINGLE H-BRIDGE MOTOR CONTROLLER CIRCUIT

SINGLE H-BRIDGE

S1-S4 ON, S2-S3OFF (for one direction).

S2-S3 ON and S1-S4 OFF (for other direction)

Switches S1,S2,S3,S4 are implemented by npn and pnp transistors. The

disadvantage of using the outputs directly from the microcontrollers for

running the dc motors is that, the logic pulse(0-5v) from the

microcontroller output does not provide sufficient torque in the motor.

With the help of this H bridge circuit we can operate the dc motors under a

sufficiently high voltage(4.8-48 volt) under the control of the output logic

pulses from the microcontroller.

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The bases of a pair of npn and pnp transistors(as shown in the above figure) are

combined and given a common Logic A. Similar arrangement is also made for

Logic B. These Logic A and B are used in controlling the motion of the motor.

For example, if A is given Logic 0 and B Logic 1, then the pnp transistor of Logic

A arrangement and npn transistor Logic B arrangement turns ON. Whereas the

remaining two transistors remains in OFF state. Thus a conducting path is

established between Vcc And Gnd via the motor (as shown in red). Since the

motor is under some potential difference rotation takes place in a particular

direction( clockwise or anti-clockwise ). Thus by selecting the logic state of A and

B the motion of the motor is controlled. The advantage of this circuit is by using

Logic 1 and Logic 0 (0v and 5v from the microcontroller) we are controlling the

motor under potential difference Vcc where Vcc can take values from 4.8v to 48v.

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PICTORIAL REPRESENTATION OF DIFFERENT

COMPONENETS IN N.E.O.BOT

1 MICROCONTROLLER BOARD

2 SENSORS

3 CHASSIS

4 REMOTE CONTROL UNIT

5 DC GEARED MOTOR WITH WHEELS

6 USB AVR PROGRAMMER

7 N.E.OBOT

TOP VIEW

SIDE VIEW

FRONT VIEW

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1 . AVR ATMEGA8 MICROCONTROLLER BOARD

The image on the left is a readymade Atmega8 development board built

on a FR-4 PCB material. We have improvised on this design and built a

custom made Atmega development board omitting some extra features

from the standard board according to our requirements. In the whole

process optimization was the key.

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2. IR SENSOR MODULE

The circuit of the IR sensor module on the left exhibited a small range of

sensitivity range. The circuit was remodeled which showed a wide range

of sensitivity. In other words the module remained active/sensitive to the

IR rays for a wide range of resistance values

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3. CHASSIS

This is the image of the NEOBOT chassis with DC geared motors fitted

with tracked wheels. The L293D and IC 7805 mounted with a heat sink

is housed within.

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4. REMOTE CONTROL UNIT

The NEOBOT is made wireless with RC5 coded IR Remote control. Ideal for

making any DC motor controlled robot. It can control upto 1Amp of current on

each channel .It can Drive 2 motors (Connect two motors in parallel for 4 wheeled

robot) in skid steer control with three stage speed control and 2 DC motors without

sped control.

Control 2 DC motors with Skid Steer Control with 1Amp capacity each

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3 stage Speed Control On 2 robot driving DC Motors

2 DC motors operated forward and backward on different buttons 

Functions on Remote Control

Action Effect

Press Forward Both Motors Forward Robot Moves Forward

Press Left

Right Motor Forward

Left Motor Reverse

Robot turns Left

Press Right

Right Motor Reverse

Left Motor Forward

Robot turns Right

Press ReverseBoth Motors Reverse Robot Moves Backward

Press 1 Robot Speed Minimum

Press 2 Robot Speed Medium

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Press 3 Robot Speed Maximum

5. DC GEARED MOTOR WITH WHEELS

DC geared motor which gives good torque and rpm at lower voltages. This motor

can run at approximately 150 rpm .

Features

Working voltage : 3V to 9V

40gm weight

3 Kgf.cm torque

No-load current = 60 mA, Stall current = 700 mA

High quality Plastic Tracked Wheel for motors with 6mm diameter.

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68mm diameter

2cm width

Hole diameter 6.1 mm

6. USB AVR PROGRAMMER

The above USB AVR programmer can be used to program most of the

microcontrollers from the AVR family either using the standard

Atmel 6pin ISP header or the standard Atmel 10pin ISP header. The above

programmer itself contains an Atmega8 micrcontroller loaded with the firmwire.

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The 3mm red LED indicates power from USB port whreas the 3 mm green Led

indicates that the programmer is busy.

AVR USBASP PROGRAMMER CIRCUIT

USBASP is well known USB programmer for Atmel AVR microcontrollers USB

ASP is made of an Atmega8 and few components. The programmer uses a

firmware driver that makes this programmer attractive to many amateurs.

The core of USBASP adapter is Atmega8 microcontroller clocked by 12MHz

crystal. Soldered board is ready to be connected via simple USB cable with B type

connector (Computer side needs A type of connector). Resistors R2 and R6 are

current limiting resistors, that protect computer USB port. Resistor R7 helps

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computer to recognize device as LS (Low Speed). Diodes D1 and D2 indicates

about data transfer. Header SV1 is compatible with STK200/300 just 4 and 6 pins

are used for RXD and TXD (may be used for other purposes).

SCK signal can work at two frequencies 375kHz and 8kHz which can be selected

by Jumper JP3. If Jumper is unconnected, then SCK speed is 375kHz. Low speed

SCK is used when MCU is clocked with low speed oscillator like 32kHz.

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Jumper JP1 is used for programming adapter itself via ISP adapter. And last

Jumper JP2 is used for powering adapter from USB port (not recommended)

7. NEOBOT

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SENSING UNIT

What is sensor?

A sensor is a device that measures a physical quantity and converts it into a signal

which can be read by an observer or by an instrument. For example, a mercury-in-

glass thermometer converts the measured temperature into expansion and

contraction of a liquid which can be read on a calibrated glass tube.The NEOBOT

senses the outer environment through its 2 IR sensors interfaced with the

Atmega8 microcontroller via pin 23 and 26(PC0 and PC3 respectively).

IR (INFRA-RED) SENSORS

Infra red sensors are the most often used sensor by amateur roboteers.

Understanding how they behave can help address many of your requirements and

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would suffice to address most of the problem statements for various robotics

events in India. Be it a typical white/black line follower, a wall follower, obstacle

avoidance, micro mouse, an advanced flavor of line follower like red line follower,

etc, all of these problem statements can be easily addressed and granular control

can be exercised upon your robots performance if you have a good operational

understanding of Infra red sensors

OPERATION:

When the Tx is forward biased, it begins emitting infra red. Since it‟s not in visible

spectrum, you will not be able to see it through naked eyes but you will be able to

view it through an ordinary cell phone camera.

The resistance R1 in the above circuit can vary. It should not be a very high value

(~ 1Kohm) as then the current flowing through the diode would be very less and

hence the intensity of emitted IR would be lesser. By increasing the current

flowing in the circuit, you can increase the effective distance of your IR sensor.

However, there are drawbacks of reducing the resistance.

Firstly, it would increase the current consumption of your circuit and hence drain

the battery (one of the few „precious‟ resources for any embedded system) faster.

Secondly, increasing the current might destroy the Tx. So, the final choice should

be a calculated trade off between these various factors.

The receiver diode has a very high resistance, typically of the order of mega Ohms

when IR is not incident upon it. However, when IR is incident upon it, the

resistance decreases sharply to the order of a few kilo Ohms or even lesser. This

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feature forms the basis of using IR as a sensor. You will need to connect a

resistance of the order of a few mega Ohm in series with the Rx. Then tap the

output voltage at the point of connectivity of these two resistors. Remember, the

value of R2 can vary depending upon the Rx diode you are working with. You are

advised to first check the resistance of Rx diode with no IR incident upon it and

then select the value of R2 for decent performance.

A complete Tx-Rx circuit is given below

Case1: WHEN NO IR IS INCIDENT UPON THE Rx When the IR Tx is above

a black line, the black line will absorb all the IR and will not reflect an appreciable

amount of IR for the Rx to receive. If you are making an obstacle avoiding robot,

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then when there is no obstacle in front of the IR Tx, Rx will not receive back the

transmitted IR. However, when an obstacle comes in front of the Tx, it will reflect

the IR incident upon it and hence Rx will receive the IR. In this case, the output

voltage of the sensor = 2.5v. Hence the input voltage at pin 2 =2.5v. Input voltage

at pin2 > input voltage at pin3 ; Output1=> logic 0

Case2: WHEN IR IS INCIDENT UPON THE Rx The resistance of Rx will

sharply fall and hence the output voltage would be around 1.8v - 1.5v depending

upon your choice of Rx and R2.

Spectral distribution of IR LED and phototransistor sensitivities

IR led

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Infrared (IR) light is electromagnetic

radiation with a wavelength longer than

that of visible light, measured from the

nominal edge of visible red light at

0.7micrometres, and extending

conventionally to 300 micrometers. These

wavelengths correspond to a frequency

range of approximately 430 to 1 THz,[1] and include most of the thermal

radiation emitted by objects near room

temperature. Microscopically, IR light is

typically emitted or absorbed by

molecules when they change

their rotational-vibrational movements.

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IR LED PHOTODIODE PAIR

In our sensor circuit module we have used IR LED as transmitter and photodiode

as IR receiver.

SENSOR CIRCUIT WORKING

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IR SENSOR CIRCUIT

In the circuit the positive input terminal of the voltage comparator LM358 is fed

from a voltage divider bias . The input to the negative terminal is the voltage drop

across the diode.

The voltage comparator LM358 in the above arrangement constantly compare the

voltage levels at its input terminals. If the input at the positive terminal is greater

than its voltage level at the negative terminal the output of LM358 switches to

logic high or 5V .When the reverse casehappens the output switches to logic 0 or

0 V.

The above switching in the voltage comparator is being utilized for sensing and

detecting particular environment in the NEOBOT.

When IR rays from IR LED falls on the photodiode upon reflection from a

reflective surface, current starts flowing in the diode thus turning it on , and the

corresponding voltage drop across the diode also drops( Since the photodiode is in

ON state).

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Thus the input at the negative terminal of LM358 now becomes much lesser than

the input at the positive terminal and output of LM358 switches to logic

HIGH(Also indicated by the red Indicator LED).

Thus vicinity to some reflective surface is indicted by the glowing red LED

LM358

GENERAL DESCRIPTIONThe LM358 series consists of two independent, high gain, internally frequency

compensated operational amplifers which were designed specifically to operate

from a single power supply over a wide range of voltages. Operation from split

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power supplies is also possible and the low power supply current drain is

independent of the magnitude of the power supply voltage. Application areas

include transducer amplifiers, dc gain blocks and all the conventional op amp

circuits which now can be more easily implemented in single power supply

systems. For example, the LM358 series can be directly operated off of the

standard +5V power supply voltage which is used in digital systems and will easily

provide the required interface electronics without requiring the additional ±15V

power supplies.

FEATURES• Internally frequency compensated for unity gain

• Large dc voltage gain: 100 dB

• Wide bandwidth (unity gain): 1 MHz (temperature compensated)

• Wide power supply range: — Single supply: 3V to 32 or dual supplies: ±1.5V to

±16V

• Very low supply current drain (500 μA) essentially independent of supply voltage

• Low input offset voltage: 2 mV

• Differential input voltage range equal to the power supply voltage

• Large output voltage swing

UNIQUE CHARACTERISTICS

• In the linear mode the input common-mode voltage range includes ground and

the output voltage can also swing to ground, even though operated from only a

single power supply voltage.

• The unity gain cross frequency is temperature compensated.

• The input bias current is also temperature compensated.

ADVANTAGES

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• Two internally compensated op amps

• Eliminates need for dual supplies

• Allows direct sensing near GND and VOUT also goes to GND

• Compatible with all forms of logic

• Power drain suitable for battery operation

CALCULATIONS :

Assuming Vcc to be equal to be 5V and all the resistors fairly ideal, the

approximate calculations are shown below:

Since Vcc is 5V, the voltage divider supplies 2.5V to the positive input terminal of

the voltage comparator.

This can also be calculated by :

V = I*R2 = [5/(2*1000) ]*1000 = 5/2 = 2.5V

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Now with no applied illumination photodiode is in off state and a very small

current called “dark current “ exists in the device. Therefore almost the whole of

Vcc is reflected to the negative input terminal in the absence of illumination.

With applied illumination ,the current starts flowing through the reverse biased

photodiode and now since a conducting path is available through the photodiode

the voltage drop( must be less than 2.5V gets reflected in the negative input

terminal, thus switching the output status of LM358 to logic HIGH indicating a

reflective surface has been discovered in the path of the robot.

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HOW IT WORKS IN OUR PROJECT:

The sensor circuit module reads the environment and sends the necessary signals

to the microcontroller accordingly. The microcontroller itself interprets the signals

received from the sensors to take the intelligent decisions on its own for the motion

of the NEOBOT.

.As soon as the microcontroller receives a status signal from the sensors it

interprets the same and decides what to do on its own according to some

predefined algorithm. In this project when the microcontroller receives a logic

HIGH the algorithm dictates the microcontroller to act normally and move

forward. When it receives a logic LOW from the sensors the microcontroller

interprets that the NEOBOT has encountered an edge, so it has to move backward

some distance and then take left or right turn according to necessity. In this way

the autonomous mode is incorporated in the Project NEOBOT.

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IR SENSOR MODULE

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ADVANTAGE OF IR SENSOR MODULE

Low power requirements Low circuitry costs Simple circuitry

MOTION CONTROL:-

Components utilized for NEOBOT motion control:

1. IC L293D (Dual H-Bridge Motor Controller IC)

2. DC geared motor.(with gear box)

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L293D is a dual H-Bridge motor driver, So with one IC we can interface two

DC motors which can be controlled in both clockwise and counter clockwise

direction and if you have motor with fix direction of motion the you can make use

of all the four I/Os to connect up to four DC motors. L293D has output current of

600mA and peak output current of 1.2A per channel. Moreover for protection of

circuit from back EMF ouput diodes are included within the IC. The output supply

(VCC2) has a wide range from 4.5V to 36V, which has made L293D a best choice

for DC motor driver.

TRUTH

TABLE OF

L293D LOGIC

STATE

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A B STATUS

0 0 MOTOR HALT

0 1 CLOCKWISE

ROTATION

1 0 ANTICLOCKWISE

ROTATION

1 1 MOTOR HALT

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DC Motors-Working

Structure

:Rotating armature-electromagnet.Armature enclosed between a set of permanent magnets

.Commuter –Rotary switchwhich reverses the direction of electric current twice every cycle.

DC Motors-Torque and R.P.M

Torque is the amount of turning force.

T=Kt*I I: Current through armature.

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R.P.M is rotations per minute and is proportional to the voltage applied.

E=Ke*w w: Angular velocity

•V=Rin*I + Ke*w

PROGRAMMING THE ATMEGA8

MICROCONTROLLER

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1> Creating a C file using AVR

Studio 4 software

2> Creating the hex file using

AVR GCC COMPILER

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3> Preparation for flashing the

microcontroller using

ExtremeBurner software

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4> Flashing the microcontroller

in progress

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5> Microcontroller flashed and

loaded with the required hex

file.

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CONCLUSION:

Future Aspects:

In the present scenario, such an automatic car may seem to be unrealizable for the

roads in India. But in developed countries, especially in Japan, such smart cars

have already hit the roads. Leading car manufacturing companies like NISSAN,

are switching over to making of such cars that would be something more than mere

means of transport. Apart from the human tragedy, there is a high cost and much

inconvenience associated with traffic jams, emergency services and property

damage as a consequence of road accidents Much experimentation has been done,

and is still going on, at universities around the world, to arrive at decent obstacle

detection systems to be used in connection with highway traffic, to bring down the

rate of traffic fatalities. 

Other future prospects include:

1. Military applications :

Military usage of remotely controlled military vehicles dates back to

the first half of 20th century. Soviet Red Army used remotely

controlled Teletanks during 1930‟s in the winter war and early stage

of World War II. There were also remotely controlled cutters and

experimental remotely controlled planes in red army. Remote control

vehicles are used in law enforcement and military engagements for

some of the same reasons. The exposure to hazards is mitigated to the

person who operates the vehicles from a location of relative safety.

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Remote controlled vehicles are used by many Police Department

Bomb-squads to defuse or detonate explosives.

UNARMED AREIAL VEHICLES (UAVs) have undergone a

dramatic evolution inn capability in the past decade. Early UAV‟s

were capable of reconnaissance missions alone and then only with a

limited range. Current UAV‟s can hover around possible targets until

they are positively identified before releasing the pay load of

weaponry

2. Autopilot application & Driver Assistance

UAV‟s will likely play an increased role in search and rescue in the

us. This was demonstrated by the successful use of UAV‟s during the

2008 hurricanes that struck Louisiana and Texas.

3 Automated Highway systems

4. Unmanned Transportation

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Future scopes of Improvement:

a) Here we have used a basic power supply circuit. But in future we can also

eliminate the use of wires by incorporating a battery or solar panel. This

solar panel would reduce electricity consumption and also our project will be

working on renewable energy.

Solar cells can give a backup for 3 days. There’s no problem of power cut

also. This will make the model more environment friendly.

b) The IR SENSOR module can be modeled to detect static or slow moving

obstacles also.

c) The robot can be manually driven by using an RF controller thereby

eliminating the need of line of sight operation altogether.

d) Infusing a SPYCAM with the robot an extrasensory vision is obtained.

Using this the robot can be controlled to venture into places where human

intervention is harmful such as bomb threat zones, fires etc.

e) Adding Gas sensors, Temperature / Heat sensors the robot can be modified

into fire fighting robot.

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A PPENDIX

MICRCONTROLLER PROGRAMMING

// Project name : Edge Avoider for Atmega8 mini

// Compile Date : 22/2/2012 Time : (16:21)

// Designed By : AYAN MAJUMDER AND SAIKAT ROY

/* ___________________________________________________

Connection settings of Kit

PWM LED-------------->PB1

RIGHT MOTOR(+)------->PB1

RIGHT MOTOR(-)------->PB2

LEFT MOTOR(-)-------->PB3

LEFT MOTOR(+)-------->PB4

BUZZER--------------->PB0

LDR------------------>PC5

BOOTLOADER Condition Check-----PC2(if 0 bootoloader section else

program execution section of Flash memory)

RESET----------------->PC6

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Crystal Oscillator----PB6 and PB7

left sensor---------->PC0

right sensor--------->PC3

Temperature sensor------>PC1

sound sensor------------>PC2

*********DTMF sensor connection********

DTMF D0---->PC0

DTMF D1---->PC1

DTMF D2---->PC2

DTMF D3---->PC3

VB=Battery Supply

VCC=regulated 5V+

Gnd=ground(0V)

VR1=Contrast of LCD

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#include<avr/io.h>

#include<util/delay.h>

void wait(float sec, int freq) //wait function to create time delay

{

for(int i=0;i<(int)(46*sec);i++)

_delay_loop_2(0);

}

void main()

{

DDRC=0b0000000; //set PORTC as input port

DDRB=0b00011110; //PB1, PB2, PB3, PB4 as output port

int ls=1, rs=1; // define & initialize ls, rs integer as 1 to

// acquire the left sensor status in ls

and //right sensor status in rs

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while(1) // create infinite loop

{

ls=(PINC&0b0000001); //acquire only left sensor status connected at

PC0

rs=(PINC&0b0001000); // acquire only right sensor status connected at

PC3

if((ls==0b0000000)&(rs==0b0000000)) //check sensor status for both

sensor OFF

{

PORTB=0b00001100; //move back

wait(1.5, 12); //keep on moving back for 0.5 sec

PORTB=0b00010000;

wait(0.4, 12); //keep on turning right for 0.5 sec

ls=1; //set sensor status on

rs=8; //set sensor status on

}

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if((ls==0b0000001)&(rs==0b0000000)) //check sensor status for

left sensor=ON and

// right sensor=OFF

{

PORTB=0b00001100; //move back

wait(1.5, 12); //keep on moving back for 0.5 sec

PORTB=0b00010000; //turn right

wait(0.4, 12); //keep on turning right for 0.5 sec

ls=1; //set sensor status on

rs=8; //set sensor status on

}

if((ls==0b0000000)&(rs==0b0001000)) //check sensor status for

left sensor=OFF and

// right sensor=ON

{

PORTB=0b00001100; //move back

wait(1.5, 12); //keep on moving back for 0.5 sec

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PORTB=0b00000010; //turn left

wait(0.4, 12); //keep on turning left for 0.5 sec

ls=1; //set sensor status on

rs=8; //set sensor status on

}

if((ls==0b0000001)&(rs==0b0001000)) //check sensor status for both

sensor ON

{

PORTB=0b00010010; //move forward

ls=1; //set sensor status on

rs=8; //set sensor status on

}

}

}

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NEOBOT LOGIC FLOWCHART

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BASIC WORKING

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COLOUR CODE FOR RESISTORS:

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DETAILED IC SPECFICATIONS

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IC 7805

IC L293D

IC LM358

IC ATMEGA8

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IC 7805

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IC L293D

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IC LM358

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IC ATMEGA8

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TOTAL CURRENT RATING OF PROJECT

No of components components Current Ratings ( mA)

1 Microcontroller 150 mA

2 IR sensor 80 mA*2=160mA

1 Motor driver 150 mA

7 LED 5X 5mA= 25mA

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APPROXIMATE PROJECT BUDGET

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BIBLIOGRAPHY

HTTP://WWW.GOOGLE.COM

HTTP://WWW.HOWSTUFFWORKS.COM

HTTP://WWW.IEEE.CO.IN

HTTP://WWW.ATMEL.COM

HTTP://WWW.DATASHEETCATLOG.COM

HTTP://WWW.AVRFREAK.NET

HTTP://WWW.ELECTRONICSFORYOU.COM

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