H∞/μ robust control of vibration for an ultra-precision grinding machine

A 6-degree-of-freedom vibration isolation system for an ultra-precision grinding machine has been developed. This system uses air springs as passive vibration isolation elements and giant magnetostrictive actuators as active vibration isolation elements. The displacement and velocity of the ultra-precision grinding machine can be chosen as the output feedback variables for the controller. With the Hinfinity/mu frequency shaping synthesis theory, a robust controller can be designed for the ultra-precision grinding machine, which is a nonlinear control system with uncertain disturbances. The method has an advantage comparing with the linear feedback control method, with which the dynamic performances and control accuracy of the system may become worse while the nonlinearity and disturbances exist. The simulation results show that the new vibration control method has stronger robustness, better dynamic performances and higher control accuracy than the common linear feedback control method.