Optimization of adaptive feedforward repeatable run-out cancellation for positioning control system of hard disk drives

Abstract

To increase the recording density of hard disk drives, suppression of the disturbances is essential. In this paper, we focus on the suppression of repeatable run-out. This paper presents the design method of an adaptive feedforward cancellation (AFC) which can suppress a periodic disturbance. AFC is adaptive filter. The algorithm can be converted into a linear time-invariant (LTI) model. The LTI model is considered to be a peak filter for a closed loop system. Therefore, parameters of AFC should be designed in consideration of a closed loop characteristics. The proposed method can design the parameters that can achieve a vector locus to recede from the critical point [− 1, 0] on the Nyquist diagram. As a result, convergence performances and stability performances of AFC are optimized in frequency domain. The effectiveness of the proposed method is verified by the simulations and experiment of the hard disk drive.