Multirate track-following control with robust stability for a dual-stage multi-sensing servo system in HDDs

This paper proposes a multirate design method for robust track-following controllers in hard disk drives (HDDs). The HDDs to be considered are dual-stage multi-sensing systems. A track-following problem, which takes into account robust stability, is formulated as a periodic time-varying version of the standard mixed H2/H∞control problem. This problem is solved via the solution of linear matrix inequalities. Simulation results show that multirate controllers can achieve much better track-following performance than single-rate controllers, while achieving the same guaranteed robust stability margin.