Oh K., Shin Y., Lee J., Kim K.

As environmental vibration requirements on precision equipment become more stringent, use of pneumatic isolators become more popular and their performance is subsequently required to be further improved. Performance of passive pneumatic isolators is related to various design parameters in a complicated manner and, hence, is very limited especially in low frequency range by chamber volume. In this study, transmissibility behavior of the pneumatic isolators depending on frequency and dynamic amplitude is presented and the maximum performance which can be achieved by the design change will be discussed. Then, an active control technique, i.e. time delay control, which is adequate for a low frequency nonlinear system, is proposed. A procedure of applying the time delay control law to a pneumatic isolator is presented and its effectiveness in the transmissibility performance is shown. Comparison between passive and active pneumatic isolators will be made.