Six Degree-of-freedom Microvibration Hybrid Control System for High Technology Facilities

With the view to achieving a more perfect microvibration-free working environment for high technology equipment such as semiconductors and optical microscopes, the authors investigate the use of a 6-DOF microvibration hybrid control system to mitigate two types of vibration (ground motion and direct disturbance). This hybrid control system comprises a table, five air springs as passive mounts and eight magnetostrictive actuators as active control actuators. To facilitate the feedback control and performance evaluation of the hybrid control system based on the one-third octave band spectra with the absolute velocity being the target, the analytical model of a hybrid control system that incorporates magnetostrictive actuators is established in the absolute coordinates. The control performance of the platform with a hybrid control system is assessed by comparing with the case of the platform with a passive control system. Simulation results indicate that the proposed platform with hybrid control system for microvibration is superior to that with passive control system because of its higher control performance against ground motion and direct disturbance for a wide range of frequencies.