ON-ORBIT IDENTIFICATION OF INERTIA PARAMETERS OF FLEXIBLE SPACECRAFT

The paper proposes a two-step method for the inertia parameter identification of a flexible spacecraft. Simulation result show this method can get high accuracy results and is suitable for on-orbit identification of inertia parameters of flexible spacecraft. 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 cause very little vibration by combining the optimal excitation with the input shaper. First, an optimal excitation is designed by minimizing a scalar variable calculated from the largest and smallest eigenvalue of the regression matrix instead of the condition number in the usual optimal excitation design method. Then the input shaper is designed to reduce the vibration 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. Once we get the proper excitation, the recursive least-squares algorithm is used to identify the moment of inertia matrix. Simulation results show that the new method can yield high accuracy identification results of inertia parameters and is suitable for on-orbit use.