Design and analysis of dual-stage servo system for high track density HDDs

This paper presents a design method of robust controller using the modified dual feedback controller to improve transient response in track seeking while attaining robust performance and stability in the presence of plant uncertainties. Coupled dynamics model is identified from the Newton-Euler formulation. We use discrete-time LQG/LTR controller design method. Robustness analysis is performed using the mu-analysis method. With the proposed method we are able to obtain an improved transient response. Furthermore, we can achieve the desired sensitivity functions while assuring robustness to the parameter variations to known structured uncertainties. It is demonstrated that the proposed method can be extented to short track-seek control without change of the controller structure. From simulation and experiment results, we confirm the effectiveness of the proposed method.