Identification and active feedback-feedforward control of rotor

The experimental work presented demonstrates the use of identification, feedback, and feedforward methods to control rotor vibrations. The experiments were performed on a rotor test rig having a 3-kg rotor supported by journal bearings; the first bending resonance of the rotor shaft was about 50 Hz. Identification was carried out with a method taking into account the disturbances due to rotation. The method, using a reference signal generated from speed measurement, was able to discard the forced vibrations due to the mass imbalance. The active control objective was to reduce the radial response at the rotor midpoint by an electromagnetic actuator located outside the bearing span of the rotor. The feedback system was a proportional-derivative-type controller, which increased the damping of the system. A feedforward control system was constructed to work together with the feedback controller. The control methods produced a significant decrease in the midpoint responses of the rotor at sub-critical speeds. For super-critical speeds, the decrease in the responses was more modest due to the restricted control authority. The stability of the feedforward controller was studied in order to explore the relationship between the system damping and the required modeling accuracy required by the feedforward control system.