Active vibration control of a rotor using a novel adaptive repetitive control algorithm

The paper investigates the possibility of using repetitive learning control to attenuate rotor vibrations on a rotor test rig. The test rig has a 3kg rotor supported by journal bearings and a critical speed of approximately 50 Hz. The objective is to control the radial response at the rotor midpoint by using an actuator located outside the bearing span. Control forces are generated with an electromagnetic actuator. The actual control scheme comprises of two algorithms, an inner loop collocated feedback system and an outer loop repetitive controller. The experimental results illustrate that the repetitive controller successfully attenuates vibrations at the critical speed of the rotor, increasing the operating range of the rotor beyond the critical speed. The attenuation results obtained are comparable to those achieved in earlier studies with feedforward compensation methods. The best results are achieved when the frequency of rotation enables an integer ratio between disturbance period and sample rate.