On-Orbit Identification of Inertia Parameters of Flexible Spacecraft

Abstract

Different from the identification of inertia parameters of rigid spacecraft, the vibration of flexible spacecraft caused by the excitation torque will reduce the identification accuracy. This paper presents a two-step method to design the proper excitation, which can avoid causing large vibrations. In the first step, an optimal excitation is obtained by minimizing a performance criterion, which is not the common used condition number. Then an input shaper is designed based on the frequency and damping ratio calculated from the coupling dynamics equation of flexible spacecraft. Finally the proper excitation is obtained by convolving the optimal excitation with the input shaper. Based on the proper excitation, the recursive least-squares algorithm is used to identify the moment of inertia matrix. Simulation results show that the proposed method can yield high-accuracy identification results and is suitable for on-orbit usage.