Development of a reaction wheel micro-vibration emulator for efficient jitter test of spacecraft

Abstract

this result shows that the same emulator can be used to emulate different micro-vibration sources. Secondly, the coupled RWA disturbance with a flexible structural effect is demonstrated through the micro-vibration emulator. Finally, the micro-vibration emulator is installed on a model spacecraft structure and the jitter characteristics are identified and compared with analytical predictions.

Recently, many satellite missions require a high level of precision pointing stability. However, on-board vibrations induced by mission-critical components of satellite such as the reaction wheel assembly (RWA), control moment gyroscope (CMG) and cryocooler can affect the pointing stability of the spacecraft by generating unwanted vibration, so called micro-vibration. The micro-vibration can introduce jitter problems into an optical payload system and cause significant degradation of the image quality. Above all, during the spacecraft development process, in-orbit vibrational environment and its effects on the performance of the optical payload must be predicted and analyzed in design phase in order to ensure that the established requirements on the payload are fully met. Besides analytical prediction of the jitter effects, an experimental validation of jitter effects on the performance of optical payloads using all the flight model (FM) components is most desirable. However, FM class RWA is in general not available for the micro-vibration test due to the scheduling issue or the product assurance activities. Therefore, in order to facilitate jitter test during the satellite development process, a reaction wheel micro-vibration emulator that generates the real disturbance spectrums of FMs is proposed. Single-axis and 6 DOF micro-vibration emulators are demonstrated and the performances of them are evaluated by means of disturbance characteristics similar to those of the RWA. A series of experimental works are performed to demonstrate how the developed micro-vibration emulator can be applied for the efficient jitter test of spacecraft. First of all, micro-vibration emulator is applied to various FM RWA model disturbance as a substitutes of FM RWAs. Specifically, Ithaco B and E type RWA model disturbances are demonstrated through the micro-vibration emulator