This paper presents a preliminary study of on-orbit system identification for the Advanced Earth Observing Satellite-II (ADEOS-II), which will be launched by an H-IIA launch vehicle in 2002. The proposed algorithm identifies a multi-input multi-output system as a superposition of normal modes. Numerical simulations demonstrate the validity of the proposed method and the feasibility of the on-orbit system identification using data obtained during the events in the initial check-out phase such as the reaction-wheel unloading with 1 N thrusters and the orbit change with 20 N thrusters.
