study of estimation method of microvibration with simulated satellite structure

Paper number

IAC-08.C2.3.9

Author

Mr. Osamu Takahara, Mitsubishi Electric Corporation, Japan

Coauthor

Mr. Norimasa Yoshida, Mitsubishi Electric Corporation, Japan

Coauthor

Dr. Hideki Uchida, Japan Aerospace Exploration Agency (JAXA), Japan

Coauthor

Prof. Keiji Komatsu, Japan Aerospace Exploration Agency (JAXA), Japan

Year

2008

Abstract

One of the biggest problems, is microvibration arising from Attitude and Orbit Control Subsystem (AOCS) components such as reaction wheels, mechanical gyroscopes, and moving components within the mission sensor, for satellites requiring high pointing accuracy. Therefore, microvibration tests on ground were conducted in order to assure performance in orbit for high accuracy observation satellites previously launched. In evaluating pointing error induced by microvibration, to select measurement method of microvibration test is important.
There are two measurement methods: One is the optical measurement method, and the other is the inertial measurement method. Each method has advantages and disadvantages. As for the optical method, the advantage is to measure the jitter of the mission sensor light axis directly. One of disadvantages is that it is not until the final development phase that the measurement can be done with the actual disturbance source and mission sensors. In addition, boundary condition is restricted to a fixed-free configuration. 
On the other hand, the inertial method is to measure the mission sensor light axis indirectly by detecting the translational and rotational movements of major optical elements of the mission sensor, and then by converting these movements to the pointing jitter. The biggest advantage is that the boundary condition is not restricted, and it is possible to simulate the in-orbit boundary condition with the free-free boundary condition. The disturbance level of sources and the transmissibility from disturbance sources to pointing errors of mission sensors on the free-free boundary condition, are evaluated separately by the measurement, and then the pointing stability of mission sensor is estimated with these data. Therefore, in the early development phase, the pointing stability can be estimated with the transmissibility and the predicted disturbance level of sources. In addition, based on the predicted results, it is possible to modify the structure. Based on the standpoint, the method is very efficient to develop satellites.
This presentation focuses on the inertial measurement method and transfer function synthesis method for the pointing stability estimation. In particular, the transmissibility measurement method and the accuracy of the pointing jitter estimated with the transmissibility and disturbance level of source are mentioned. For the purpose of the study, the transmissibility and the disturbance data of source ware measured with a simulated satellite structure designed by JAXA. In order to improve the estimation accuracy with the transmissibility and the disturbance date, the content of the estimation method currently under consideration, is introduced.

Abstract document

IAC-08.C2.3.9.pdf

Manuscript document

IAC-08.C2.3.9.pdf (🔒 authorized access only).

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