How to interpret position in JointStateInterface
The context is a robot with 2 drive wheels, using the ros_control diff_drive_controller.
I would like to know if it is well defined in ros_control how to interpret an increasing position value in the JointStateInterface? (We'll ignore wrap-around for the moment.)
I expected that an increasing angular position value in /joint_states meant that the wheel was rotating counter-clockwise on its axel (as viewed from the motor side.) And therefore, when a diff drive robot moves forward in a straight line, the right wheel position value would increase, and the left wheel position value would decrease.
The commercial wheeled robot I have access to does not behave this way. For it, both wheel position values increase as the robot moves straight forward.
Are multiple conventions supported? If so, how does diff_drive_controller know how to interpret the values?
