ROS Parameterize the WHEEL_SLIP_THRESHOLD in motor_node.cc

[mjstn]

I place this issue here so that perhaps somebody can make ros parameters for a new value I have put in for a threshold for when to kick in wheel slip nulling. This is a feature to help avoid wheel overheating. This is a request for assistance so we can change this parameter if required as we move forward.

I assign Teo at this time but fully expect he would find somebody to take this on and reassign to that engineer.

The change would be off of the 4wdChassisBranch and thus would merge back into that branch
Here is the value that is currently a devine that would be converted to be a ROS parameter

• Have ROS parameter for WHEEL_SLIP_THRESHOLD in motor_node.cc. Default this to 0.08

[mjstn]

This issue is on hold and would be only required if we re-start the work on MoonStar which is the only platform this applies.