Improvement of accuracy of seismic waveforms using dirsturbance observer in multi-axis shaking table systems

This paper proposes a controller design approach to achieve the high reproducibility of earthquake acceleration waveforms in multi-axis shaking table systems. The target shaking table system has an shaking mechanism to excite vibrations in multiple directions, where the cooperation control of each actuator is required to realize precise table motion. In order to conduct an accurate seismic test using the target multi-axis shaking table, a disturbance observer used to improve disturbance suppression capabilities is designed for the feedback control system of each actuator. In addition, an acceleration feedback compensation is added as the minor-loop, to suppress the resonant gain peak in the actuator, because the resonant vibration restricts the expansion of the observer bandwidth. The effectiveness of the designed control system is evaluated by conducting experiments using a test model.