Multi-Frequency Technique for Frequency Response Measurement and Its Application to Servo System with Friction

Abstract In this paper, the effect of nonlinear distortion on system identification is studied. In particular, the effect of nonlinear friction on frequency response measurement is examined. Design of multi-frequency excitation signal that minimizes nonlinear effect on frequency response measurement has been explored and the best linear approximation model has been defined. An identification method using differential No Interharmonic Distortion (NID) excitation with optimized crest factor is proposed. The method is used to identify the best linear model of a hard disk drive actuator.