An Estimation Method of Inner Pressure of Pneumatic Active Anti Vibration Apparatus Using Minimum Order Observer

Abstract

In the field of precision positioning and measurement, air-type active anti-vibration apparatuses are widely used. This apparatus equips an actively controlled air spring which has anti-resonance and resonance characteristic on frequency response. Due to this characteristic, it is known that deformation of main body occurs because of the difference of pressure in each air spring. In order to avoid the deformation of main body supported by the air springs and to manage their driving forces, the pressure feedback was especially implemented as a minor loop. However, it is undesirable to install pressure sensors in the field of industrial application because it takes cost and the sensors have low resolution for the management of the driving force. Then, this paper proposes a minimum order observer that estimates inner pressure of the air spring without a pressure sensor. Some correction gains for the observer are usually set by pole assignment method, however these gains depend on the parameters of the plant. Therefore, the observer needs adjustment of correction gains for implement. Then, this paper proposes a minimum order observer which is able to be adjusted with monitoring the measured frequency response, and clears the role of the correction gains.