Model based unbalance monitoring using augmented observer in rotor systems under the consideration of gyroscopic effect

Unbalance forces are a crucial issue in rotor systems. Often it is of interest to monitor the states of unbalances while the rotor is running in order to prevent damages to the rotor system. For the model based unbalance monitoring a rotor model is required to represent the behavior of the rotor system and the influences of the unbalances. The feasibilities of the methods are often limited by the accuracy of the system model. Accurate physical model is often hard to build especially for large scale rotor systems with unknown physical properties. In case of rotor systems with large discs, the gyroscopic effect is not negligible. It results in a rotary frequency dependent system behavior and thus makes the modeling problem more complicated. Besides the modeling problems, disturbances from initial unbalances and rotor bow are also issues to be considered in the unbalance monitoring. In this paper we formulate the disturbances and gyroscopic effect as unknown inputs, which are widely investigated in the fault detection processes and use the model of non-rotating rotor as basis for the unbalance monitoring. Augmented observer, which takes sinusoidal vibrations into consideration is used for the unbalance monitoring. The application of the method on a rotor test rig is presented in this paper.