Development of Multi-DOF Active Microvibration Emulator

Abstract

Recently, some components and payload systems installed in satellites are exposed to various disturbance sources, such as the reaction wheel assembly, the control moment gyro, coolers, and others. Because there is low damping in space, the continuous microvibration causes the degradation of the performance of various payload systems. Therefore, the development of a practical isolation system that shields against microvibration are very important and the author is on the way to developing the microvibration isolation system for the improvement on the performance of the optical payload. In order to develop appropriate microvibration isolation device for a specific payload, it is necessary to understand vibration characteristics of the main disturbance sources; modeling and analysis of disturbance sources including reaction wheel assembly and control moment gyros have been studied by many researchers. However, there are practical difficulties to obtain and perform an experiment with real flight model (FM) reaction wheel assembly and control moment gyros because of expensive price and security reasons. Generally, the disturbance characteristics of a prototype of the reaction wheel assembly or control moment gyros are significantly different from those of FM ones even when the reaction wheel type, size and wheel speed are the same. Therefore, in order to facilitate the microvibration isolation experiment during the satellite development process, this paper proposes a microvibration emulator that could generate the real disturbance spectrums of FMs. Note that the disturbance profiles are quite complex, consisting of several higher harmonics, and also changing for varying operational wheel speeds. The disturbance characteristics of FMs are typically measured in advance. First an analytical model for the RWA is presented and the development procedure for the emulator is also described. The performance of the first prototype emulator is demonstrated.