Detection and reduction of middle frequency resonance for an industrial servo

This work proposes a novel strategy for middle frequency resonance detection and reduction for the speed control of industrial servo systems. The report includes an analysis of the drawbacks of the traditional resonance reduction method based on an adaptive notch filter in the middle frequency range, and the main drawback is summarized as the difference between the resonance frequency and the oscillation frequency. In the proposed method, a self-tuning low-pass filter with a corner frequency determined using FFT results and several self-tuning rules is introduced in the speed feedback path. Consequently, the effective range of the adaptive filter is extended across the middle frequency range. The simulation and experimental results show that the frequency detection is accurate, and the resonances are successfully reduced during steady-state and dynamic speeds.