Servo control of a dual-stage actuator for a high performance disk drive. Part 2: controller design and implementation

For Part 1, see ibid., vol. 3, no. 6, p. 2523-8 (2003). In this paper we describe the controller design and implementation for a dual stage servo actuation system for a high performance disk drive. The system utilizes a standard voice coil motor (VCM) combined with a piezoelectric microactuator in a dual stage drive. The VCM provides low-speed motion with a very large stroke enabling coarse positioning and rejection of large amplitude low-frequency disturbances. The microactuator provides very high-speed motion but with limited stroke, enabling fine positioning and rejection of high frequency disturbances. The overall dual-stage system provides a high bandwidth actuation system, capable of very fine positioning despite disturbances with a wide variety of spectral content. In this paper we focus on the drive and its analysis, modeling, and simulation.