An improved model of a pneumatic vibration isolator: Theory and experiment

The design of an active controller for a vibration isolation table employing pneumatic vibration isolators requires an accurate mathematical model of the isolator. An experimental investigation of the validity of available models has been performed and indicates significant errors between predicted and observed behavior. An analysis of the model and the data suggested that a previously ignored component of the isolator, the diaphragm, plays a significant role in isolator response. This paper develops the modifications to the standard isolator model that incorporate the effects of the diaphragm. When the diaphragm is included in the isolator model, the modified model predicts time-domain and frequency-domain behavior quite closely. We conclude that the modified model of the pneumatic isolator improves markedly the accuracy of the predictions provided by the model. (C) 1998 Academic Press.