Design of Reference for High-Speed and Vibration-Less Attitude Maneuvering of Flexible Satellite

Abstract

A radio astronomical observatory satellite "ASTRO-G", which will be launched in 2012, has two characteristics: flexible appendages and high-speed and high-precision attitude maneuvering. Because of these two antithetical features, attitude control system (ACS) of ASTRO-G becomes quite challenging in comparison with those of past satellites. For such a satellite, feedforward control which is robust to model identification error is considered to be important. Nil-Mode-Exciting (NME) profiler is one of references for anti-vibration, which is designed to excite no flexible modes, and thus its robustness is considered to be of most significant. NME profiler, however, is relatively slow reference because of negligible high frequency component. In this paper, we propose Modified NME profiler which is relatively fast reference designed by convolution of NME profiler and Input Shaper. Some anti-vibration experiments are carried out to show the effectiveness of the proposed reference.

Agile and Precise Attitude Switching Maneuver of Flexible Spacecraft based on Nonstationary Frequency-Shaped Robust Control

“…The singular values of ASTRO-G model are shown in Fig. 1 (3) (4) . It shows that there are vibration modes in low frequency ranges and they could have bad influence on attitude control.…”

“…In the current scheme for the attitude control systems of flexible spacecrafts, the feedforward controller called Nil-Mode Exciting (NME) profiler has been designed to perform the agile and precise attitude switching maneuvers of the flexible spacecraft ASTRO-G (2) . With feedforward controller designed by convolution of NME profiler and Input Shaping, the two degree-of-freedom control system with ∞ H controller has been proposed for attitude control system of ASTRO-G (3) (4) . However, the stationary feedback controller could impair the performance of the feedforward controller.…”