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DESCRIPTION
in this project the robot avoid the edge of table.
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With ATMega8 µc
INTRODUCTIONThis is the robot which keeps moving on a
platform and as soon as it detects an edge, it
turns in opposite direction i.e. if it detects the
edge of platform in its front, it starts moving
backward, if it detects an edge in its left then it
turns to its right and vice versa.
Hardware Components RequiredA microcontroller (ATMega8)
IR Sensor
Comparator (LM358)
DC motor
Motor driver IC (L293D)
Wheels
Power adopter
ATMega8 Development Board
IR SensorsIR sensors give output by receiving the reflected rays
transmitted by the transmitting diode.
If the surface is black, the transmitted
ray will be absorbed and will not be
received and if the surface is white then
receiver will get the reflected ray and generate output.
IR Sensor Circuit
Motor Driver IC (L293D)It is required to supply sufficient
current to motors as microcontrollers
can’t supply that much current.
It is a dual H-Bridge motor
means it can drive two DC
motors simultaneously in both
clockwise and anticlockwise
direction.
Its input terminals are controlled
by the microcontroller.
It also includes the protection
circuit against back EMF.
Block Diagram
IR Sensor 1
IR Sensor 2
Compar
ator
Compa
rator
Variable DC
voltage
Variable DC
voltage
Microcontr
oller
Motor
with
wheel
Motor
with
wheel
Motor
Driver IC
(L293D)
Overview
IR sensors
Chassis Board
AT Mega8 µc
Comparator(
LM358)
Voltage
regulator IC
Wheel
attached with
motor shaft
DC Motor
Description It works with the signal generated
by the sensors. To avoid the
edge of platform, sensors are
mounted in front of robot at
both left and right side.
Each sensor has a motor associated with it. If it gets
the reflected light(means there is still surface below
the sensor), the comparator sends logic 1 to
microcontroller and vice versa.
Conti….
The program loaded into microcontroller takes the
decision of switching any motor ON or OFF
according to the inputs coming from the comparators
connected after each sensor.
The robot turns in the direction opposite of the sensor
detecting the edge, for this it turns ON only the motor
associated with that sensor.