Autonomous Optical Navigation Aided By Radio Beacon For Deep Space Spacecraft At Approach Phase

Deep space exploration missions have features such as long distance,long sailing time and so on.Autonomous navigation is a key technology for realizing autonomous operation on deep space spacecraft.Optical navigation is currently a hot issues of deep space explore for its advantages like high autonomy and real-time,etc..In this paper,considering the characteristics of the approach phase of deep space exploration mission,there is a research about autonomous optical navigation assisted by radio measurement.The research is aimed at obtaining navigation information,observability degree analysis,autonomous trajectory estimation and other issues.The main contents are as follows:First of all,the dynamics and observation model of the approach phase was established.The orbit motion characteristics of the space craft and the target body were analyzed.After simplifying relative orbit dynamics model,we got the relative motion equations and navigation observation model of the spacecraft in the target celestial relative coordinate system.Secondly,we did a research on feature extraction of optical navigation with star-mode.By the way of background star triangle matching and eliminating method,we achieved matching and detecting the target body in complex background.We also analyzed different imaging features of the point light source and diffused light source and then processed and extracted the line-of-sight optical features of the target body respectively using sub-pixel correlation model and edge detection method.Then we studied autonomous optical navigation based on line-of-sight vector in order to position the spacecraft during approach phase.On the basis of state equations and observation equations,a extended Kalman filter was designed to process observation information to determine the spacecraft ‘s relative position and velocity to the target body.We also analyzed observability of the navigation system respectively using geometric and numerical methods.Finally,in order to solve the unobservable limitations on the line-of-sight direction of optical navigation system,we studied optical navigation assisted by radio measurement which can improve the observability degree of optical navigation system.We imported a radio beacon to get more observation information and analyzed its observability and degree.This method achieved determining the trajectory at approach phase quickly.