Vibration isolation for parameter-varying rotor systems using piezoelectric actuators and gain-scheduled control

This paper deals with the active vibration isolation for a rotor subject to gyroscopic oscillations, where gain-scheduled H ∞ -control is used to steer an active, piezoelectric bearing. Rotating machines are often exposed to gyroscopic effects, which occur due to bending deformations of rotors and subsequent tilting of eccentric mass elements. Gyroscopic moments observed at rotors are proportional to the rotational speed and couple radial degrees of freedom. This relationship with the operating conditions renders the system dynamics well-suited for the use of linear parameter-varying models and controllers, relying on the rotational speed as an uncertain parameter. In this paper, we design linear gain-scheduled H ∞ -controllers guaranteeing both robust stability and performance within a given range of operating conditions. The paper is based on a rotor test rig with two unbalance-induced resonance frequencies in its operating range. The rotor has two protruding discs, one of which is centered between one active and one passive bearing support. The active support consists of two piezoelectric stack actuators and two collocated piezoelectric load washers. Closed-loop performance is assessed via isolation of unbalance-induced vibrations using both simulation and supporting experimental data.