Multirate adaptive notch filter with an adaptive bandwidth controller for disk drives

This paper presents the simulation results performed of a multirate adaptive notch filter with adaptive bandwidth controller for disk drives. The resonant modes of a disk drive may be uncertain and vary between units, and can also lie near or beyond the nyquist frequency. Suppressing these modes can be difficult. However, with an adaptive notch filter that is able to accurately track the resonant frequencies, the effects of such modes can be suppressed. By adding a multirate scheme to the adaptive notch filter, it can suppress modes at higher frequencies. As the multirate adaptive notch filter tracks the plant mode frequencies, the adaptive bandwidth controller ensures that stability and performance requirements are satisfied. The simulation results that are included show the benefit of the adaptive control scheme.