Optimization Of Asteroid Exploration Orbit And Autonomous Navigation Algorithm

Asteroid exploration focuses on major scientific issues such as the origin of life in the universe,and has always been the emphasis and hot spot of deep space exploration.Carrying out asteroid exploration are of great practical significance for studying the origin and evolution of the solar system,exploring possible ways of the origin of life,and ensuring the safety of the earth.There are a large number of asteroids,with the characteristics of weak gravity,irregular shape,and complex dynamic environment,which brings new technical challenges to the design of navigation,guidance and control system of asteroid probes.Based on the national asteroid exploration project,this paper conducts research on key technologies such as autonomous navigation,low thrust orbit transfer guidance and control for special problems in dual asteroid detection.According to the different dynamics characteristics,the asteroid exploration process can be divided into cruise phase and surrounding phase.The orbit design optimization of these two processes and the problems of autonomous navigation caused by these two processes have been intensively studied.The main research work includes:Define the coordinate system commonly used in asteroid exploration missions and establish the orbital dynamics model of the cruise section.Based on the two body dynamic model,an instantaneous gravity assisted model and a multi-mode electric propulsion model are established and normalized.Establish a three body dynamic model of the capture and surrounding orbit of double asteroids,derive and analyze its main dynamic characteristics,which provides theoretical support for the following chapters.Aiming at the problem of low thrust transfer orbit design and optimization,a series combination optimization strategy is proposed.First,search the possible borrowing sequence based on the improved energy state diagram,then use the particle swarm optimization algorithm to obtain the global optimal pulse transfer orbit,and finally use the pulse transfer orbit as the initial value to solve the small thrust transfer orbit optimization problem by the direct method.The simulation results show that the strategy can give full play to the global optimality of particle swarm optimization algorithm and the insensitivity of direct method to initial values,and obtain the asteroid exploration transfer orbit satisfying the engineering constraints,which provides an effective method and approach for solving the problem of multi-body transfer orbit design and optimization with low thrust.Aiming at the uncertainty of thrust model caused by low thrust orbit transfer in cruise phase,an improved adaptive interactive multi model unscented Kalman filter algorithm is proposed,which overcoms the influence of inaccurate prior information of model set on navigation accuracy,realizes coverage of navigation system state with less model numbel,and overcoms the impact of the inaccurate prior information of the model set on the navigation accuracy.Numerical simulation results show that the accuracy of position estimation and velocity estimation are improved significantly,and the robustness and anti-jamming ability of the integrated navigation system are grealty improved.Aiming at the problem of the obit design an optimization in the process of asteroid exploration and acquisition,a method for capturing orbit design using the specical dynamics of the dual asterodi system is proposed.The sun center orbit with positive inertial performance and the orbit with negative inertial performance are connected by zero velocity curve,and the decrease value of inertial performance is improved by shooting zero velocity curve,then the detector enters a bounded orbit around a small planet by applying a small velocity increment at the far arch point,and the acquisition strategy proposed is extended and applied by introducing the rotating mass dipole model in narrow asteroids.In order to solve the problem of relative autonomous navigation for double asteroid exploration,a recursive model of double star dynamics is established by using the angular velocity parameters of double stars,and a relative autonomous navigation metod is proposed which does not depend on range information.The line of sight angle of the binary satellite is used as the navigation quantity measurement to overcome the problem that the line of sight vector information is affected by the attitude pointing accuracy of the detector,and the navigation filtering divergence problem in the observation blind area is solved through the angle measurement and velocity measurement integrated navigation.A recursive initial value correction method of the binary satellite dynamics is proposed through iterative judgment,which significantly improves the estimation accuracy of the initial value of the binary dynamics.