A linear matrix inequality approach to initial value compensation for mode switching control in hard disk drive servo systems

In mode switching control from the track seeking or the track jump to the track-following control of hard disk drives, initial values of the feedback controller are tuned in order to improve the transient response. This paper presents a simple initial value compensation (IVC) method using linear matrix inequalities (LMIs) instead of the conventional method using a Lyapunov equation. The LMI includes conditions for improving the transient response performance in the L₂-norm sense and minimizing the H_infin norm of the closed loop system to reduce the controlled outputs such as plant states, tracking error, control efforts, and so on. Optimal initial values of the controller are obtained by solving an optimization problem with constraints represented by only one LMI. Finally, the feasibility is verified by a series of simulations.