抄録
In order to investigate the directional behavior of the g-jitter, a new method for three-dimensional g-jitter analysis has been developed. Both the conventional method and the new one are applied to accelerations measured during STS-65 and STS-95 Space Shuttle flights. From the FFT analysis for the low frequency band, several peaks around 5 Hz considered as the structural vibrations are observed in both results of STS-65 and STS-95. From the FFT result for higher frequency band of STS-65, strong and clear vibration peaks produced from machinery are observed. A vibration composed of single frequency component is mathematically analyzed to understand the fundamental characteristics of the behavior. The analytical result shows that any vibration composed of only one frequency can be transformed to a combination of a linear motion and a circular one on an appropriate coordinate system. In the lower frequency band, the directional motions of the structural vibrations are almost perfectly linear. On the other hand, a vibration in higher frequency band from machinery is a combination of these two motions. These results indicate that the behavior of the g-jitter can be described using a simple model with corresponding to the frequency bands.
