Resonance Suppression for Hydraulic Servo Shaking Table Based on Adaptive Notch Filter

In dynamic structure test, the specimen of hydraulic servo shaking table contains not only inertia load but also elastic load. The specimen herein is simplified as a spring-mass-damping system, and the mathematical model of the hydraulic servo shaking table is established by theoretical analysis. The coupling between specimen's elastic load and shaking table itself produces resonance phenomenon in the required bandwidth when the elastic load is not negligible, which deteriorates the system's dynamic performance and even leads to the instability of the control system. Also, the time-varying resonance frequency further aggravates the control performance of the system in the shaking test. In this paper, an adaptive notch filter based on least mean square (LMS) error principle is employed to identify the resonance frequencies online and real-time adjust the parameters of the notch filter. Simulation and experiment results show the effectiveness of frequency identification and resonance mode suppression. Compared with the existing resonance suppression scheme, the proposed method can suppress the appeared resonance mode adaptively.