Autonomous Navigation Model Design and Analysis for Mars Probe in Capture Stage

For the autonomous navigation system of Mars probe in capture stage,when the probe is approaching to Mars,the system model will vary from multi-body motion model( model 1) to two-body motion model( model 2),and observable celestial bodies are various including Mars,Phobos,Deimos and the Sun. In order to analyze the precision of different models,two state models and multiple measurement models are established. Then,based on PWCS method,FIM method and condition number method,the influences of different measurements on the degree of observability of system are analyzed under model1 and model 2. Optimal combination strategy of system model with measurement model is given by simulation results,which provides an important reference for the design of autonomous navigation system of Mars probe.