Synthesis of passive vibration isolation mounts for machine tools - A control systems paradigm

Vibration isolation and the synthesis of passive isolation mounts has been studied extensively by researchers in the space industry, automobile industry and lately the precision machine tool industry. The machine tool industry is rather unique in the sense that the machine needs to be isolated against two contradictory disturbance mechanisms which disturb the metrology loop besides exciting structural resonances on the machine and leading to error motions. These are due to seismic vibrations and payload disturbance forces that occur either due to the machining process or the motion of various components on the machine tool. This paper casts the vibration isolation problem as a control paradigm and relates the effect of the contradictory disturbance forces to sensitivity and complementary sensitivity functions. Thus, the passive isolation problem is demonstrated to be subject to the same fundamental tradeoff encountered in the design of control systems. Optimal techniques in control literature are then shown to be applicable to the passive mount synthesis. In particular, this paper describes the application of Kalman filtering techniques to the passive mount synthesis problem.