Observer design for unbalance excited rotor systems with gyroscopic effect

In state space control, system states are usually estimated using observers. In active rotor systems, observer design often faces two major problems: unbalances acting on the shaft are never known to full extent and in case of a rotor with large discs, gyroscopic effect results in system variation dependent on rotor rotary frequency. Two observer types accounting for these problems, a disturbance observer and an unknown input observer are applied to a rotor system with piezoelectric active bearings. The two approaches are compared with respect to accuracy of the estimated states, transfer behavior and expense for implementation.