Add PID to turn position control into torque control

[ducmngx]

Unless we figure out a way to change damping, kp, and stiffness during runtime. I am thinking about adding a PD or PID controller to read this position control (from the planner output) and return torque/effort input to send to MuJoCo. Doing so we will basically control the whole process, from planning to control at the lowest level.

When we use torque control, we will need to tune all these damping, kp, and stiffness numbers to make the arm super unstable (the robot will no longer send force to keep the arm still) and rely completely on our control signal. The good thing is we can potentially make the robot fails by simply sending no effort to a joint, or even a reduced force to mimic low power behavior.

I can lead this ticket but I want to hear if @Saadmaghani has any experience with PID

[Saadmaghani]

So I need a PID controller to move the jackal to its next position. I could use DWA but that would require collision checking and we're not there yet. Also, I agree with you about directly controlling the joints by giving them force. we're working at the very low level so this would be the way to go. Maybe DWA and other local planners will use this under the hood.

Also, I need the PID controller now so I can make a simple one and then we can expand it to include joints too. Also python motion planning has a PID controller .

PS. You've made 2 issues about PID controllers and I think they talk about the same thing? Lets close one of them.