New design of multirate digital control scheme for computation saving

In the implementation of control algorithms on consumer electronics (CE) products such as hard disk drives (HDD), the computational load for real time control should be kept minimal for technical and economical reasons. In this paper, based on the current multirate control method with interlacing technique for computation saving, a redesigned multirate control scheme is proposed to reduce the computational load of digital servo controller. In the proposed scheme, the amount of computation has been uniformly reduced by interlacing the slow-mode control outputs. Moreover, the system performance is maintained in the sense that the output of the redesigned multirate slow-mode controller can match with the output of the normal-rate slow-mode controller at slow sampling instances. The proposed method is evaluated by applying it to a HDD servo system.