Resonance Suppression Using Bi-quad Lag Compensator for Industrial Servo System with High Inertia Ratio and Resonance Frequency Variations

This paper presents a design methodology for a bi-quad lag compensator to suppress resonance in industrial servo systems. Generally, a system with high inertia ratio between motor and load has a poor stability margin. In addition, it is hard to design filters to suppress the resonance when the resonance frequency of the system changes by the position of the moving mover. In this paper, a design methodology for a bi-quad lag compensator is presented. First, open-loop Bode plots are obtained offline at different positions of the load. Then, the poles of the bi-quad lag compensator are set to be larger than the largest anti-resonance frequency among the obtained Bode plots, and the zeros of the bi-quad lag compensator are set to be smaller than the smallest resonance frequency among the obtained Bode plots. The design procedure can improve the stability margin of the system when the inertia ratio is high or when the frequency response changes by the mover position. Experiments show that this methodology is effective in suppressing vibration.