Active control of electro-rheological fluid embedded pneumatic vibration isolator

Vibration isolation is crucial to better product quality in precision machinery, and can be achieved through either passive or active vibration control systems. Although passive pneumatic vibration isolators have excellent isolation characteristics at high frequencies, the external vibrations may be amplified at resonance frequencies. The requirement of lower transmissibility over the entire frequency ranges leads to the development of active pneumatic isolators. In this study, an active pneumatic vibration isolator embedded with an electro-rheological-fluid damper is designed. A fuzzy controller and a pneumatic servo control system are used to regulate the air flow into or out of the top chamber of the isolator, thus decreasing the transmissibility at high frequencies. The controller also forwards the control signals to control the strength of the electric field applied to the ER damper, thus controlling the damping force needed to reduce the amplified vibrations at natural frequencies. The results show that the proposed active pneumatic vibration isolator embedded with an electro-rheological-fluid damper can effectively enhance the vibration isolation performance over the entire frequency range.