Feedforward control of the three main disturbances to the pneumatic isolation table

Pneumatic vibration isolation tables are employed in the field of semiconductor manufacturing and precision measurement. There are three main flow disturbances such as flow variation, non-uniformed flow and random flow drops of the supplied air that cause the fluctuations of the isolation table. Multi-connection air regulators are often used for the control of flow variation of the supplied air. However, the multi-connection air regulators lead to the pressure loss of the compressed air. Previously, we used two feedforward control methods for the control of flow disturbances. Both methods utilized pressure sensor to measure the supplied air pressure and provide feedforward control signal to the actuators. One method used air spring and the other used voice coil motor (VCM) as the actuators. The current study proposes a flow meter instead of a pressure sensor to measure the supplied air flow at the output of the air compressor and send feedforward signal to the actuator, VCM, to control the flow disturbances to the isolation table. Until now, a flow meter has been used just for monitoring the supplied air flow to the pneumatic isolation table. The objective of this study is to utilize a flow meter in practical control of the flow disturbances.