Abstract
This paper presents an industrial application for an air type anti-vibration apparatus based on the consideration of difference between its apparatus and a velocity sensor. The former apparatus has the function to attenuate the vibration on the isolated table transmitted from the floor. The later sensor detects mechanical vibration. Then, they have mutually different functions. However, both feedback control systems look alike, namely, these have a velocity feedback to add damping and a weak position feedback to maintain the equilibrium state. However, in case of the anti-vibration apparatus, the velocity feedback is constructed by using absolute acceleration signal. While, in case of its feedback for the velocity sensor, relative velocity signal through the differentiation of the relative displacement is used. Consequently, when the velocity feedback gains are increasing, the frequency responses have mutually different shapes. Then, by modifying the velocity feedback from the absolute acceleration on the isolated table to the relative acceleration between the isolated table and the floor, the anti-vibration apparatus can easily change to the velocity sensor itself. In the case of velocity sensor-like air type anti-vibration apparatus that suffers long period earthquake ground motions, the relative displacement between floor and isolated table can be reduced and then its apparatus becomes robust against earthquake ground motions in terms of mechanical collision.
