Fractionated Earth Observation Satellite and its navigation information integrated plan

Earth Observation Satellite should have the ability of functional modules and autonomous orbit changing. Autonomous navigation is need during orbit changing. To meet the future requirements, Fractionated Earth Observation Satellite (FEOS) is put forward. Special Force would not be zero during orbit changing because Gravity is not the only force acting on satellites, so it is potential to apply Strapdown Inertial Navigation System (SINS) to navigation. But the navigation precision of SINS is worse and worse as time goes on. Global Positioning System (GPS) and Star Sensors (SS) are supposed to aid SINS and get the better navigation precision with integrate navigation information from different navigation systems. The Extend Kalman Filter(EKF) of the SINS/GPS/SS is constructed to analyze integrated navigation performance. Simulations show that the position and velocity error of pure SINS is quickly divergent while SINS/GPS/SS could supply the better estimation of position, velocity and attitude. With the GPS and SS, the navigation precision of SINS is improved and the default of noncontinuous output for GPS is weaken by SINS.