Discrete-time composite nonlinear feedback control with an application in design of a hard disk drive servo system

Abstract

In a typical disk drive servo system, two or more types of controllers are used for track seeking, track following, and track settling modes. This leads to the problem of mode switching among these controllers. We present in this paper a unified control scheme, the discrete-time composite nonlinear feedback control, which can perform all the above functions in hard disk drive (HDD) servo systems with actuator saturation. The proposed scheme is composed by combining a linear feedback law and a nonlinear feedback law. The linear feedback law is designed to yield a fast response, while the nonlinear feedback law is used to increase the damping ratio of the closed-loop system as the system output approaches the command input. In the face of actuator saturation, this control law not only increases the speed of closed-loop response, but also improves the settling performance. Implementation results show that the proposed method outperforms the conventional proximate time-optimal servomechanism by about 30% in settling time.

High-Performance Tracking Controller for Discrete Plant Using Nonlinear Sliding Surface

“…Subsequently, the CNF controller was extended for general higher order singleinput-single-output (SISO) and multiple-input-multiple-output (MIMO) systems in [18]- [20] for state-and output-feedbackbased controls. In [20] and [21], a controller based on this idea is proposed for discrete systems. In [21] and [22], experimental results of CNF controllers are reported for hard disk servo control, and results show the great improvement in the transient performance.…”

“…In [20] and [21], a controller based on this idea is proposed for discrete systems. In [21] and [22], experimental results of CNF controllers are reported for hard disk servo control, and results show the great improvement in the transient performance. Recently, in [23], CNF is implemented on XY -table position control application.…”

Design of Nonlinear Systems in the Frequency Domain: An Output Frequency Response Function-Based Approach

“…1 The design of the parameters 1 3 1 ,, k k c and 1 c of the nonlinear system in Fig.1 can therefore be transformed to the design of the same parameters but for the NARX-M-for-D (6).…”

“…N engineering practice, the design of a system is often concerned with the determination of the system parameters that can be used to achieve desired system responses under considered loadings or input excitations [1][2][3]. The frequency domain design of linear systems [4][5][6] based on the traditional concept of Frequency Response Function (FRF) has been widely applied in engineering system designs such as, e.g., the design of the dynamic properties of vibration absorbers [7], vehicle suspensions [8], and aero engine blades [9].…”

Practical Implementation of a Novel Anti-Windup Scheme in a HDD-Dual-Stage Servo-System

“…With particular reference to HDD-servo systems, a continuous-time output-feedback control scheme capable of dealing with actuator saturation has been recently presented in [1], and, in terms of a discrete-time state-feedback control scheme, in [ 30]. Both these control schemes combine a nonlinear and a linear control element of fixed structure and apply to single input systems such as VCM-actuators.…”