Research On High-precision Autonomous Integrated Navigation Technology For Mars Probe

Mars exploration is an important part of deep space exploration.High-precision autonomous navigation technology is a necessary condition to ensure the success of future Mars exploration missions.With the establishment of China’s 2020 Mars exploration mission and subsequent deep space missions,to develop high-precision deep space exploration autonomous navigation technology has become an inevitable mission of Chinese scientific research workers.This thesis takes China’s 2020 Mars exploration project as the engineering background,the high-precision autonomous integrated navigation technology of the cruise phase,the orbiting phase and the entry phase is studied.Firstly,based on the simplified celestial geometry model,the celestial brightness gradient model and the celestial texture model,a series of Mars optical images of the cruise terminal phase is generated.The image processing algorithm is used to extract the optical measurement information as the input of subsequent navigation algorithm.Then,the autonomous integrated navigation approach based on Mars/Sun/X-ray pulsars measurement is proposed for Mars exploration cruise phase,and the orbit dynamics model and navigation measurement model of cruise phase are established.For the navigation system under different measurement models,the PWCS observability analysis method is used to analyze the the observability degree of the system,and then the nonlinear filtering technology is used to design the navigation experiment.The comparison verification results between the observability degree and the navigation accuracy are obtained which provide a theoretical way for rapidly selecting the models and constructing the navigation systems.Next,the autonomous integrated navigation approach based on optical/radio/X-ray pulsars measurement is proposed for Mars exploration orbiting phase,and the orbit dynamics model and navigation measurement model of orbiting phase are established,the observability of the integrated navigation system is analyzed.The adaptive extended Kalman filter is used to suppress the process noise with unknown magnitude,and the navigation precision is higher than traditional EKF and UKF.Finally,the autonomous integrated navigation approach for entry phase based on IMU/FADS measurement is studied,and the six-degree-of-freedom dynamic model and navigation measurement model of entry phase are established,and the aerodynamic parameters of the probe are expanded as state parameters for joint estimation.And the observability degree of each state is studied by the singular decomposition of the observability matrix.The IMU output and dynamics model are used as the system model respectively,and several different types of navigation methods are comparative studied which provide a theoretical reference for choosing the optimal navigation scheme for Mars exploration entry phase.