A Simple Frequency Range Selector to Reduce the Unstable Behavior of Active Vibration Isolation

Abstract

In an active vibration isolation system using velocity feedback, the phase–lead due to high-pass filter and the phase–lag due to time delay limit the controller gain. This paper extends and applies a simple frequency range selector to increase the critical control gain. The selector uses the isolated mass's acceleration, velocity, and displacement and is tuned by two knobs. Our proposed approach has simple static switching law, suppresses both low and high frequency control, and does not add additional phase–lead or phase–lag. A simple expression of the effective gain is presented to give insight into the influence of two tuning knobs. Numerical simulations and a simple experiment are performed to illustrate the controller's effectiveness under harmonic and random disturbances.