An Identification Experiment for Simultaneous Estimation of Low-Order Actuator and Windage Models in a Hard Disk Drive

This paper describes an identification experiment designed in order to simultaneous estimate low-order parametric models for the servo actuator and windage disturbance dynamics of hard disk drives. The challenging identification issues imposed by the experiment, namely the closed loop operating conditions and the low-complexity requirements about the estimated models, are overcome by using an identification method that has been recently developed by one of the authors and called "extended two-stage method". The experiment is carried out on a commercial 3.5 in, 7200 rpm hard disk drive operating in standard track following mode and with his own cover, so that realistic working conditions for both the servo actuator and the internal airflow pattern inducing windage are reproduced. Low order, control relevant actuator and windage models are estimated using the proposed identification method. The effectiveness of the method is assessed by comparing its results with those obtained using standard parametric and non-parametric identification methods.