I' m trying to develop a simulation model of a 4-wheel omnidirectional vehicle.
I'm using the torque actuation in the revolute joints connecting the wheels with the chassis. A feedback loop with a PI controller in each joint keeps the angular velocity constant. The control works fine with the wheels in the air (no contact with the floor).
But when I let the wheels get in contact with the floor, the angular velocity neasured in the revolute joints shows a lot of 'noise':
The movent of the vehicle on the floor is correct. it moves forward-backward, left-right and CW-CCW as expected but the mesured angular velocity of the wheels is awfull. I'm sure that these disturbances are due to the spatial contact forces. I've tried changing the contact and friction parameters but I can not get rid of the noise.
Find attached the file solids and the simulation model if you want to try it.
Any help will be very appreciated.