1997 Volume 33 Issue 8 Pages 805-811
System identification experiments for a large space structure (LSS) have been performed as ones of on-orbit experiments using Engineering Test Satellite-VI (ETS-VI) which was launched in August 1994. The purpose of the system identification experiments is to check the validity of a mathematical model for ETS-VI which was previously obtained by ground experiments. There are two types of excitation methods by gas jet thrusters of Reaction Control System (RCS), that is, an impulse excitation and random excitation. In this paper, we concentrate on the latter excitation method. As an output signal, the satellite attitude along the excited axis is monitored during the experiments. Two kinds of methods are utilized for system identification. One is based on polynomial models such as a prediction error method (as a special case, least-squares method is included), and an instrumental variable method. The other is a subspace-based method which has been of great interest recently. The purpose of this paper is to compare these system identification methods based on experimental data. It will be shown that the subspace method is promising for system identification of LSS.
