Control of an air spring type anti-vibration apparatus using minimal order observer

In the field of precision positioning and measurement, an air-type anti-vibration apparatus is widely used. In order to levitate an isolated table and increase the damping, a position sensor and an acceleration sensor are mounted on the anti-vibration apparatus. The pressure sensor is also utilised for the pressure feedback control, which improves the transmissibility. In the implementation of pressure feedback, the high-resolution pressure sensor is needed. It is, however, expensive. To solve this problem, one approach is to use the observer instead of the pressure sensor. By using the theory of observer, we can choose the pole to determine the convergence of observer. Therefore, in this paper, we investigate effects of parameters of the observer with different pole assignment. The parameters are tuned by considering the frequency characteristics of the anti-vibration apparatus.