Identification and decentralized control of a dual-actuator hard disk drive system

The dual-actuator hard disk drive with two voice coil motor actuators mounted in the diagonal corners of the baseplate allows faster data access with relatively slow spindle speed. However, the mechanical interaction between the actuators tends to affect the head positioning accuracy. In this paper, we use the circle-fit modal testing method to identify the dual-input dual-output frequency response model of the dual-actuator plant. We discuss the decentralized control scheme for the dual-actuator tracking servo. The servo loop decomposition reveals that the interaction induces narrow-band vibrations near the crossover frequency. We propose a phase-lead interaction filter with a slight change to the loop stability to suppress the vibrations. Experimental results on a dual-actuator prototype show that the position error signal 6σ value due to interaction vibrations is reduced by 61% with the interaction filter in combination with the decentralized control scheme.