Robust friction compensation in HDDs

Friction compensation via position measurement only in hard disk drives (HDD) is considered in this paper. A robust nonlinear adaptive controller is designed which uses only the motor position (i.e., the output) for feedback and does not require knowledge of electromechanical system parameters, such as parameters in the friction model, rotor inertia, etc. Reduced-order Lunberger observer is introduced and observer-based backstepping procedure is carried out in this paper. Simulation results are depicted to show the performance of the advocated controller.