Autonomous celestial navigation method of asteroid probe based on angle measurement and velocity measurement

Autonomous navigation is one of the key technologies to ensure the successful implementation of deep space exploration mission. Aiming at the requirement of celestial autonomous navigation ability of asteroid probe in practical engineering tasks, the integrated autonomous navigation method combined celestial spectral velocity measurement with celestial image angle measurement is proposed to realize continuous autonomous, real-time and high-precision navigation of asteroid probe. Considering the limitation of traditional radio navigation on the ground and the high requirement for autonomous survivability of asteroid probe, the task of asteroid explorer has an urgent need for real-time and autonomous navigation ability. The current autonomous navigation method mainly extracts the angle measurement information of the probe relative to the target celestial planet from the optical image information of the target celestial planet, and then calculates and determines the navigation state of the probe. However the accuracy of velocity estimation by this navigation method is limited, which still cannot fully meet the current demand of asteroid probe. In view of the shortcomings of the main existing autonomous navigation methods, this paper proposes a direct velocity measurement method based on astronomical spectrum, and combines it with the astronomical angle navigation method to form the integrated autonomous navigation method. Based on the integrated autonomous navigation method, the navigation system model and filtering algorithm are derived, and the observability and navigation accuracy performance of the integrated navigation system are analyzed. Taking the Ceres exploration mission as an engineering background, the simulation results show that the stellar velocity information measured by astronomical spectroscopy can greatly improve the integrated navigation performance. And the accuracy of position and velocity estimation results of the probe can restrain the influence of errors more effectively and enhance the reliability of navigation system. Compared with the traditional terrestrial radio navigation or angle measurement navigation methods, the integrated navigation results have higher accuracy and better real-time performance, which can provide accurate navigation information for asteroid probe orbit modification. The integrated navigation method derived in this paper is effective, reliable and easy to implement. It provides a reference for the implementation of the asteroid exploration project and the subsequent major deep space missions in China.