Adaptive rejection of the dominant frequency components of non-repeatable runout in hard disk drives

This paper presents an adaptive compensation scheme for the dominant frequency component of non-repeatable runout (NRRO). The frequency of the dominant component is estimated on-line by the least mean squares (LMS) algorithm within a short time window. Based on the frequency estimate, the basis function algorithm is applied to adaptively identify the magnitude and the phase of the dominant component. With the identified frequency, magnitude and phase, an estimate of the dominant component is constructed and then canceled by the control signal. The performance of this compensation scheme is demonstrated by simulation on a realistic hard disk drive model. Extension of the scheme to handle multiple dominant frequency components is presented also.