Autonomous orbit navigation of two spacecraft system using relative line of sight vector measurements

Autonomous orbit navigation of two spacecraft system is considered with the relative line-of-sight vector measurements between two spacecraft system. Observability of the system with the available measurements is investigated using the linear observability analysis, and the relative state variable observability is obtained. Error covariance analysis based on the extended Kalman filter is considered, and the position and velocity state estimations of two spacecrafts are obtained by using the extended Kalman filter. The estimation results show that the position can be estimated with an accuracy of about 200 m and the velocity about 0.2 m/sec. This estimation result is confirmed through the Monte-Carlo simulation. The results clearly show that a fully autonomous on-board orbit navigation system is feasible by using an electro-optical means for measuring the relative LOS vector.