How to use ros_control and diff_drive_controller using python?

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What do you actually want to do? Command a diff drive mobile base to a certain position? Something else?

I am trying to move a two wheeled Lego EV3 robot using ROS on a laptop and sending commands to the motors through MQTT message protocol. I already know how to make a base_controller that convert ROS twist messages to left and right motors commands but I want to learn how to use ros_control and ros_diff_controller and I didn't know that the only way is using C++.

This may be due to a misunderstanding of how you'd interface with the diff_drive_controller: as you can read here it accepts geometry_msgs/Twist inputs that then get converted to individual wheel velocities. You don't typically "use it from C++" (if that means: directly calling methods on/in it).

First of all thanks for your comments. I know that diff_drive_controller takes a geometry_msgs/Twist as an input but what I don't know is how it is converted to each wheel velocity. - Where can I get the individual wheel velocities? - How can I send these velocity values to a python script?

Regards.