An active vibration isolator was developed for semiconductor manufacturing machines using electro-magnetic(EM) levitation force. The spring is composed of a pneumatic elastic chamber and a magnetic actuator. The actuator has a coil and a permanent magnetic plate and is installed inside of the chamber. The mechanical and electronic parts are designed to operate under a weight of 2.0 tons. An air mount is constructed for the experiment with a stone surface plate, 4 active air springs, 4 gap sensors, a DSP controller, a linear power amp and vibration measurement systems. The impulse response of the air mount was monitored before and after the active control. The time duration was reduced by 77% in the impulse response. The maximum peak in frequency domain was reduced by 62%. We also found that the active system can avoid the resonance caused by the natural frequency of the passive system.

A 4 × 4 matrix model with three degrees of freedom is proposed as a means for controlling microvibrations and applied to an electromagnetic isolator. The model was derived from an assumption based on small-and low-frequency vibrations. The coordinates of the 3 DOF was composed of the 4 variables, representing a vertical position, pitch, roll, and a proof term. The coordinates were calculated from the 4 position sensors in the isolator and formulated into a 4 × 4 matrix, which possesses inversive full rank. The electro-magnetic isolator was built for a simulated machine in semiconductor manufacturing and consisted of a heavy surface plate, sensors, amps, a controller, and air springs with electromagnets. The electromagnets are installed in a pneumatic chamber of the individual air spring. The performance of the 3 DOF model was experimented and compared with that of a 1 DOF model in an impact test. The settling time in the result was reduced to 25%.

A 4 × 4 matrix model with three degrees of freedom is proposed as a means for controlling microvibrations and applied to an electromagnetic isolator. The model was derived from an assumption based on small-and low-frequency vibrations. The coordinates of the 3 DOF was composed of the 4 variables, representing a vertical position, pitch, roll, and a proof term. The coordinates were calculated from the 4 position sensors in the isolator and formulated into a 4 × 4 matrix, which possesses inversive full rank. The electro-magnetic isolator was built for a simulated machine in semiconductor manufacturing and consisted of a heavy surface plate, sensors, amps, a controller, and air springs with electromagnets. The electromagnets are installed in a pneumatic chamber of the individual air spring. The performance of the 3 DOF model was experimented and compared with that of a 1 DOF model in an impact test. The settling time in the result was reduced to 25%.