H∞-based active microvibration control of an ultra-precision machine tool

A 6-degree-of-freedom microvibration isolation system for an ultra-precision machine tool has been developed. This system uses four air springs as passive vibration isolation elements and eight giant magnetostrictive actuators as active vibration isolation elements. Four vertical actuators and air springs are set in parallel to make use of the giant magnetostrictive actuators effectively. The displacement and velocity of the ultra-precision machine tool are chosen as the output feedback variables for the controller. The H. control approach is used to design the active vibration control system. Computer simulations and experiments are carried out to verify this system's microvibration control performance. The simulation and experimental results show that the developed active vibration control system has good isolation performance against the floor disturbance over wide frequency area.