I have seen that the motor-rotor of an automotive throttle body is always vibrating a little bit within the backlash of the gearbox.
This "trick" is used to avoid/minimize the non-linear behaviour of stick-slip during position controlling.
I wonder if the VESC would allow to let the motor vibrate within a very low amplitude to avoid stick-slip. Any ideas how this could be tested with the VESC?
more explanation regarding stick-slip (from http://machinedesign.com/bearings/avoid ... d-bearings):
Stick-slip chatter commonly shows up on initial start of a machine when static friction in the bearings temporarily restrains shaft rotation. As the shaft then winds up, torsional force rises until it exceeds the restraining static friction. At this point, friction drops to its kinetic value as rotation initiates and the rotor “jumps ahead” as it dissipates its stored elastic energy.
Repetition of this sequence during slow-speed rotation often produces a stop-start jerking pattern,...