Identification of unbalance and sensor runout on rigid rotor supported by magnetic bearings (2nd report, identification method and experiment by the weighted-incremental least square on-line method)

In this paper, we have conducted identification experiments on the mass unbalance and high order sensor runout in a turbo molecular pump supported by active magnetic bearings (AMB), by using the proposed identification method. Firstly, output signals from the displacement sensors are converted and stored in the real time Linux. The mass unbalance and high-order sensor runout are identified using the weighted-incremental least square on-line method from the stored displacement data. Next, by attaching known plural weights on the rotor, the resulting unbalance and higher-order sensor runout were identified using the proposed method. Finally, the reproducibility of the identification experiment and the effectiveness and accuracy of the proposed identification method were verified by an already-known higher-order signal, which synchronizes with the rotor and corresponds to the sensor runout, is added to the rotor and estimate the added high order input signal.