Modeling and Compensation of Pivot Nonlinearity in Hard Disk Drives

In this paper the authors propose a new, straightforward approach to derive model of the pivot nonlinearity in the hard disk drive. The proposed nonlinear model is not based on classical pivot nonlinearity models. It is derived using frequency domain measurements obtained for different amplitudes of the actuator excitation current. One of the advantages of the obtained model is that it is derived using actual experimental measurements conducted under the real operating conditions of the hard disk drive. Experimental results show good match of the derived model with both the frequency and time domain measurements. The derived model is subsequently used for feedforward compensation of the pivot nonlinearity and the experimental results are presented. Simulation studies are carried out for adaptive neural network compensation using the derived model.