Trajectory tracking control of voice coil motor under gravity disturbance

In comparison with traditional servo motor systems, direct drive linear motors do not require any intermediate transmission link and have the advantages of simple mechanism, fast dynamic response, high precision, low noise and little vibration. In this work, we investigated the tracking control problems of a linear voice coil motor placed on the vertical plane. Based on the internal-mode principle, a dynamic feedback tracking control law was designed to achieve trajectory tracking control ensuring the convergence of tracking errors. For comparison purpose, the proposed control law and the traditional three-closed-loop motor controller are both used to the same platform. Experiment results indicate that the proposed internal mode controller can achieve better performance of tracking errors with smaller smooth control input than that of the traditional one.