Automated Multiple Robust Track-Following Control System Design in Hard Disk Drives

This brief proposes a new design procedure for track-following control systems in hard disk drives. The procedure is automated, in the sense that, for given experimental frequency response data of the suspension arm dynamics and a model structure, it automatically derives a transfer function set with uncorrelated parametric uncertainties. Subsequently, for the transfer function set, a given controller structure, and closed-loop performance specifications in the frequency domain, it automatically designs a partition of the uncertainties and corresponding multiple robust controllers. For the transfer function set derivation, nonlinear principal component analysis is utilized to determine correlations among coefficient parameter variations. For multiple robust controller design, a nonsmooth optimization approach is taken to deal with complex multiobjective control problems, as well as to reduce the computational cost, which is often an issue in multiple robust controller design. Simulations and experiments on actual hard disk drives demonstrate the usefulness and efficiency of the proposed procedure.