neobot thesis
TRANSCRIPT
Project N.E.O.BOT
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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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