Modeling and cancellation of pivot nonlinearity in hard disk drives

This paper considers the issue of modeling the pivot nonlinearity in a typical hard disk drive, taking into account viscous friction, Coulomb friction and hysteresis effects. It presents a nonlinear compensator design, based on a proposed model, to make the compensated system behave like a double integrator regardless of the magnitude of the input current. It describes extensive experiments, carried out in both time domain and frequency domain, to show the effects of pivot nonlinearity and the effectiveness of the compensator.