Development of a totally active magnetically suspended gyro

A magnetically suspended gyro (MSG) is developed and its performances is estimated. In the MSG, a disk-type rotor is connected to a synchronous motor through a fluid bearing and the motor is fixed to the frame of the floator. The floator is suspended by magnetic force without any mechanical contact so that highly accurate measurement is possible. In accordance with this concept, a three-degrees-of-freedom (DOF) active MSG was developed. However, because of poor damping in the passive suspension and the low resolution of the displacement sensors, the measurement accuracy was relatively low. To solve these problems, a six-DOF (totally) active MSG is designed and fabricated. The frame of this gyro is an octagonal. The motion of the frame is controlled by eight electromagnets. The performance of the gyro is evaluated through measurement of the double-axis angular velocity. The advantages of totally active suspension are investigated. Sufficient damping rapidly reduces the influence of disturbances. Then, the influence of sensor noise is examined. The results of this examination show that the accuracy of the angular velocity measurement is improved by using highly sensitive displacement sensors. Next, the dynamic range is measured. This experiment shows that the MSG can provide precise angular velocity measurement in a low-frequency region.