line following robot This is a small line following robot designed to follow a white line drawn on a black surface. The software can be changed to interchange the colours. The software still has lot's of room for improvement but works well. It constantly corrects wrong moves using feedback mechanism which forms a closed loop control system.
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mechanical design
It has two DC motors in wheelchair
design. Direction of the robot is controlled by controlling speeds of
the two motors. Lets say the speeds are
Right wheel : SpeedR
Left wheel : SpeedL
To control the speed of the motor controlled power is fed by PWM (
Pulse Width Modulation ) technique.
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electronic design
Processor AVR ATmega16 [ the ADC feature
comes in handy to read output of sensors ]
Motor driver : L293D ( 2 )
Sensors : IR LED-photodiode pair ( 2 )(
non-modulated )
Power supply : Li-Ion cells ( 2 ) 1700mAHr giving 8V regulated with
voltage regulator
control algorithm and software
Lets say the two sensor outputs, i.e. the
intensity of reflected light sensed at the two sensor positions is
Sensor Left : SensL
Sensor Right : SensR
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If Err is the error of sensors from mean
position then it will be proportional to the difference between the two
sensor readings
Err = K * ( SensR - SensL )
Where K is constant of proportionality
If Err is a +ve quantity then we must
drive Left motor a bit faster than the right i.e. the speed of right
motor must be increased a bit and speed of motor right be decreased a
bit
This is called Proportional Control
Line follower robot
video ( 9.6 MB )
SpeedL = CntrSpeed + Kp * Err
SpeedR = CntrSpeed - Kp * Err
