Chatter reduction in sliding mode control of a disk drive actuator

摘要

A sliding mode controller for controlling a read/write head actuator in a magnetic disk drive storage system wherein a voice coil motor connected to the actuator operates to adjust the position of the read/write head over a selected data track recorded on a magnetic medium. The sliding mode controller comprises a technique for reducing chatter associated with the inherent operation of such a controller-rapid switching between gains to force the observable phase states to follow a predetermined phase state trajectory. While tracking the centerline of a selected track, the sliding mode controller generates a motor control command by multiplying an actuator position error and an actuator position error velocity by respective switching gains. When seeking to a new track, the controller reduces switching noise by disabling the actuator position error and generating the motor control signal responsive to the actuator position error velocity alone. The sliding mode controller further comprises an integrator for integrating the actuator position error during tracking in order to compensate for biasing forces that can cause a DC offset from the selected track's centerline.