Adaptive disturbance rejection in the presence of uncertain resonance mode in hard disk drives

Abstract

Abstract-An adaptive on-line scheme is designed to identify the uncertain and time-varying resonance modes in hard disk drive servo systems. Based on the identified results, the uncertain resonance mode is extracted and a peak filter is designed accordingly to provide stronger capability of disturbance suppression. The scheme does not require any extra excitation signal nor additional signal processing for the parameter identification. Compared to conventional method, the rates of learning and error convergence are greatly increased. The scheme can provide good stability margin at high frequency subject to the variation of the resonance frequency and the peak gain. Simulation results show the validity and effectiveness of the proposed scheme.

Switching-based Adaptive Output Regulation for Uncertain Systems Affected by a Periodic Disturbance

“…where x ∈ R n , u ∈ R, y ∈ R and d ∈ R represent the state, the input and the output of the plant, and the external disturbance, respectively. Our target is to design the control u(t) that eliminates the effect of the disturbance d(t) on y(t), under the least information on the plant model (1). More precisely, no information on the structure of A(µ), B(µ), C(µ) is required, apart from the assumption of robust stability given below, and the fact that the plant parameter vector µ ∈ R p ranges on a given known compact set, P ⊂ R p .…”

“…Let the parameter vector θ ∈ R 2 be defined as θ (µ) = (Re{W (jω * )} −Im{W (jω * )}) where W (s) := C(µ)(sI − A(µ)) −1 B(µ) denotes the transfer function of system (1). Assuming that θ is known, following [12], Problem II.1 can be solved by the interconnection of the external model of the disturbance…”

“…The problem of rejecting periodic disturbance has long been of special interest in control community, due to its commonly appearance in practical applications [1]- [4]. From a methodological perspective, the periodic disturbance cancellation problem can either be cast in the general framework of the output regulation problem [5], [6] or tackled by means of Adaptive Feedforward Cancellation (AFC) techniques [7], [8], for which a large body of literature exists.…”

Adaptive Nonlinear Output Tracking Control With Rejection of Unmatched Biased Sinusoidal Disturbances for Nonlinear Systems

“…The rejection of sinusoidal disturbances is of particular interest in control systems because these disturbances commonly occur in practice [1]. Sinusoidal disturbances occur in a large number of applications, such as rotating magnetic bearings [2], precise piezoactuated nanopositioning [3], hard disk drives [4], optical disk drives [5], rotating pumps in cryocooler expanders [6], helicopter rotor blades [7], and aircraft landing on oscillating carriers [8].…”

Multirate Adaptive Compensation of Uncertain Resonances Beyond the Nyquist Frequency

“…To overcome this problem, adaptive notch filters or chasing peak filters that follow the resonant frequency have been developed (see Kang et al [2005], Ohno et al [2006], Levin et al [2011], and Masashi [2004]). In addition, several adaptive control schemes were also proposed to compensate for uncertain resonant modes (Wu et al [2000], Tee [2007], and Hong et al [2010]). However, all these adaptive methods are designed for resonant modes below the Nyquist frequency.…”