abhinav-prajapati / ros2_arduino_bridge

Adapting ros_arduino_bridge for PI-Robot

Arduino Motor Controller

This code turns an Arduino into a motor controller! It provides a simple serial interface to communicate with a high-level computer (e.g. running ROS), and generates the appropriate PWM signals for a motor driver, to drive two motors.

This is a fork of the original code, with some changes, and removal of the ROS nodes (see this repo for an alternative). Check out README-orig.md for the original README.

As I only have need for a subset of the functionality, I have no idea what does and doesn't work, beyond what is detailed below. Feedback/improvements are welcome (though no promises on how quickly I'll respond). I currently only use the L298N driver, and the Arduino encoder mode.

TODO

• Finish this README

Functionality

The main functionality provided is to receive motor speed requests over a serial connection, and provide encoder feedback. The original code has provisions for other features - e.g. read/write of digital/analog pins, servo control, but I've never used them.

The main commands to know are

• e - Motor responds with current encoder counts for each motor
• r - Reset encoder values
• o <PWM1> <PWM2> - Set the raw PWM speed of each motor (-255 to 255)
• m <Spd1> <Spd2> - Set the closed-loop speed of each motor in counts per loop (Default loop rate is 30, so (counts per sec)/30
• p <Kp> <Kd> <Ki> <Ko> - Update the PID parameters

Gotchas

Some quick things to note

• There is an auto timeout (default 2s) so you need to keep sending commands for it to keep moving
• PID parameter order is PDI (?)
• Motor speed is in counts per loop
• Default baud rate 57600
• Needs carriage return (CR)
• Make sure serial is enabled (user in dialout group)
• Check out the original readme for more

TODO (maybe)

• Document PID tuning
• Make the speed input counts per second
• Add/test more driver boards
• Add/test other functionality