Modeling and cancellation of pivot nonlinearity in hard disk drive

In this paper, the modeling issue of the pivot nonlinearity in a typical hard disk drive is considered. Viscous friction, Coulomb friction and hysteresis effects are taken into account. Based on the proposed model, a nonlinear compensator is designed to make the compensated system to behave like a double integrator regardless of the magnitude of the input current. Extensive experiments are then carried out in both time domain and frequency domain to show the effects of pivot nonlinearity and the effectiveness of the proposed compensator.