Reduced-order H∞ loop-shaping controller design for nonlinear continuous-time HDD systems using Hankel-norm approximation

Abstract

This paper presents the design and analysis of a reduced-order H∞ loop-shaping controller for nonlinear continuous-time Hard Disk Drive (HDD) systems. Utilizing the Hankel-norm approximation, we systematically reduce the controller order, aiming to preserve system performance while enhancing computational efficiency. MATLAB simulations are employed to model the HDD system dynamics and to evaluate the controller’s efficacy. Performance is quantitatively assessed using the Integral of Time multiplied by Absolute Error (ITAE) criterion. Results indicate that a 10th-order controller achieves a balanced trade-off between robust control, disturbance and noise attenuation, without significant performance loss. This approach demonstrates the potential for reduced-order controllers in complex HDD systems, offering a pathway towards practical implementation in high-precision industrial applications.