Repeatable and non-repeatable disturbance rejection for hard disk drive control

Summary form only given. A disturbance rejection control scheme is developed for hard disk drive servo control. The control scheme overcomes the drawback of typical internal-model-based repetitive control schemes which cancel repeatable disturbances but amplify disturbances at other frequencies. A systematic way of designing a disturbance rejection controller which is capable of attenuating both repeatable disturbances and non-repeatable disturbances is proposed. This is achieved by combining the original internal-model-based repetitive controller with a loop shaping filter. Simulations using disturbances reconstructed from actual drive position error measurements have been carried out to show the effectiveness of this control scheme.