Abstract: In order to study the approach for autonomous determination of relative orbit for satellite formation flying,the relative motion equations of formation satellites were established based on orbit element differences.The inter-satellite distance and orientation measurements were chosen as the observation information.Instead of using the Extended Kalman Filter,the relative orbit state estimation was achieved through an Unscented Kalman Filter.The simulation results show that the relative orbit can be precisely determined by this method and it is validity for autonomous determination of relative orbit for formation satellite flying.

Key words: Relative motion, Orbit parameter, Autonomous orbit determination, Kalman filter, Formation flight, Satellite