Motion Control - NEX ROBOTICS FIREBIRD V ATMEGA 2560 Hardware Manual

Fire Bird V ATMEGA2560 Hardware Manual

3.8 Motion control

Fire Bird V robot has two 75 RPM DC geared motors in differential drive configuration along
with the third caster wheel for the support. Robot has top speed of about 24cm per second. Using
this configuration, the robot can turn with zero turning radius by rotating one wheel in clockwise
direction and other in counterclockwise direction. Position encoders are mounted on both the
motor's axles to give a position feedback to the microcontroller.
Figure 3.17: DC geared motors and position encoders
Motion control involves velocity and direction control. Motors are controlled by L293D dual
motor driver which can provide up to 600mA of current to each motor. To change the direction
of the motor, appropriate logic levels (High/Low) are applied to L293D's direction control pins.
Velocity control is done using Pulse Width Modulation (PWM).
LEDs are connected at the input stage of the motor driver for quick interpretation of the motion
commands.
Figure 3.18: Motor Drivers
© NEX Robotics Pvt. Ltd. and ERTS Lab, CSE, IIT Bombay, INDIA 28