Discrete-time Robust Nonlinear Feedback Control for an HDD Servo System Design

This paper presents a discrete-time robust nonlinear control method to achieve fast and accurate set-point tracking for servo systems subject to actuator saturation and disturbances. The idea here is to use a combination of composite nonlinear feedback (CNF) control and disturbance estimation cum compensation. The CNF control is responsible for superior transient performance, i.e., to guarantee a fast response with low overshoot, while the disturbance estimator/compensator is used to remove the steady state bias that would otherwise be existent due to disturbances. Practical application in a micro hard disk drive servo system will be given to demonstrate the effectiveness of this control method