Friction compensation of a mini voice coil motor by sliding mode control

This paper presents a sliding mode controller to compensate the friction of mini voice-coil motor (VCM), embedded with guide pins, for position control in compact camera module (CCM) application. In the VCM, actuator full stroke is only 0.35 mm or less, nonlinear friction force falls into mismatched condition and um-level resolution is required. With proposed controller, arbitrarily small steady state error can be approached by pole placement of the sliding mode state equation. The performance is firstly simulated with a physical VCM model. The experimental result is then presented to demonstrate the proposed controller is able to avoid stick-slip oscillation that usually yields when using classic controller, such as PI controller.