Robust QFT Control of a Piezo-Based Vibration Isolation System With Consideration of Hysteresis Effect

In this paper, we investigate a three-degree-of-freedom (X-Y-Z) piezo-based vibration isolation platform. The hysteresis effect together with system uncertainties are represented by an approximate model. The approximate model consists of a variable gain and variable time-delay which are the functions of the input magnitude and frequency. Experiments are performed to identify the parameters of the proposed approximate model. To achieve robust performance of the isolation system with consideration of the hysteresis effect, quantitative feedback theory (QFT) controller is proposed. The hysteresis model is naturally built into the template of plant. It is shown from closed loop experiments that the designed controller can achieve high disturbance rejection within the bandwidth of 10–60Hz for the MIMO vibration isolation system.