Abstract
This paper considers model reduction and robust control of an active vibration isolation system which is composed of a rigid platform and supporting air springs. The objective of control is to realize low compliance in the low frequency range for accurate position and attitude control, and maintain high compliance in the high frequency range for good vibration isolation properties. The system is modeled by identification theory, and the modeling error is described as multiplicative uncertainty. Model reduction is carried out by removing the state variables in the balanced realization, which neither contribute to the input-output relation of the model nor increase the modeling error. A controller is designed preserving robust stability, which minimizes the sensitivity in the low frequency range.
