Modelling and control of a high speed, long travel, dual voice coil actuator

This paper presents a dual voice coil actuator which is suitable for both long travel and high speed short stroke movements. The actuator is arranged in the form of two voice coils motors (VCM), with the small one responsible for high speed/short travels, and the larger one for lower speed and longer travels. However, this arrangement introduced problems of inter-VCM motion coupling disturbances, and undesirable mechanical characteristics on the small VCM. To overcome them, this paper proposed to investigate the full control model of the dual voice coil actuator, and to use this knowledge as compensation blocks in the control system to reduce the control nonlinearities and coupling effects. Due to the nonconventional geometry of the dual VCM actuator, a novel method of obtaining the model parameters has been developed. Results show that the proposed control structure has substantial improvement over traditional dual PID control in terms of speed, accuracy, disturbance rejection and control robustness.