Switching control of an air type anti-vibration apparatus under earthquake ground motion

This paper presents the control method for the continuous operation of semiconductor exposure machines under earthquake ground motion. In our method, floor vibration feedforward control and relative acceleration feedback control are switched on or off, and the gain of the acceleration feedback controller is changed. The acceleration of the floor vibration, the relative displacement between the isolated table and the floor, and the difference of spectral intensity (SI) value are utilized as switching signals. By using the switching control strategy, effects of unknown earthquake can be compensated. The effectiveness of the proposed method is shown by simulation and experimental results.