Research On Autonomous Navigation And Stationkeeping For Quasi-periodic Orbit In The Earth-moon System

The probes about the Earth-Moon collinear libration points are suitable forscientific data collection, relay communication and navigation network for deepspace tasks. The study of those orbits has significant theoretical and practicalsignificance. For Earth-Moon system, however, the applications are morechallenging than those in the Sun-Earth system, in part because of the shorter timescales, the larger orbital eccentricity of the secondary, and the fact that the Sun actsas a significant perturbing body in terms of the gravitational force as well as solarradiation pressure. Instead of the periodic orbits in the circular restricted three bodyproblem, the orbits in real Earth-Moon system present the quasi-periodicity.Therefore, the system modeling, orbit design, autonomous navigation and orbitmaintance for the orbits about the Earth-Moon collinear libration points are morechallenging. With the support of the Chinese Science National Foundation-theFundamental Research of Spacecraft Robust Control and Application, thisdissertation focuses on modeling, orbit design, autonomous navigation and orbitmaintance for the probes about the Earth-Moon collinear libration points.First of all, since the Circular Restricted Three-body Problem (i.e CR3BP) isthe basic model for the Earth-Moon libration missions, the Earth-Moon system isdecribed in the CR3BP condition as well as the analytical solutions for Earth-Moonlibration orbits. However, the CR3BP cannot precisely reflect the motions of theprobes around the Earth-Moon libration points and the traditional high-order modelis too complex. Therefore, this dissertation proposes an accurate model for theprobes around the Earth-Moon libration points with simple structure, which usesthe standard ephemeris to represent the motions of the Sun and the Moon in order totake the direct and indirect influence of the Sun into account as well as theeccentricity of the Moon. Simulation shows that, compared with the CR3BP, theelliptic restricted three-body model and restricted four-body model, the proposedmodel is more accurate. Secondly, this dissertation studies orbit design problem for the Earth-Moonlibration quasi-periodic orbit. Designing orbit with multiple shooting method andhigh-accuracy ephemeris model is the latest method which can overcome sometraditional defects in the restricted three-body problem, such as the disregard for theSun’s perturbation. Due to complex calculations for patch points and lots ofcoordinate transformations involved in this method, two improvements areproposed in this dissertation to ameliorate the condition. Firstly, the traditionalephemeris model is reformed and established in the Earth-Moon rotating frame,which can avoid large amounts of coordinate transformations during the multipleshooting. Secondly, based on the characteristics of quasi-periodic orbits about thetranslunar libration point, instead of massive calculations, simple coordinatetransformations can provide necessary information for patch points of multipleshooting. Simulation results show that the proposed method can be used effectivelyto design quasi-periodic orbits about the translunar libration point.Subsequently, this dissertation studies the autonomous navigation andstationkeeping problem, which are mutual coupling problems. An initial error couldtrigger a fast divergence of the unstable state and drift a probe far away from thenominal orbit. The station-keeping system must be started soon after the probe isinjected, while the navigation system should provide convergent results within ashort period and the results need to be accurate enough for the station-keepingsystem.Therefore, the constraints from the stationkeeping system must be consideredduring the design of autonomous navigation. Sun-Earth-Moon (i.e., SEM)autonomous navigation problem is investigated for the quasi-lissajous orbit and theQuasi-periodic Halo orbit about the translunar libration point. Generally, SEMnavigation method can offer a convergent estimation by using orientationinformation. However, due to the unstable nature of the translunar libration orbit, itis still indispensable to further prove that only orientation information canguarantee the convergence. Therefore, three sensor configurations are studied tofind an appropriate sensor configuration for translunar libration probe. The observability analysis and experiences from Genesis probe, ARTEMIS probe areused to evaluate the feasibility of each sensor configuration. Autonomousnavigation is obtained by extended Kalman Filtering.In addition, the constraints from the autonomous navigation system must beconsidered during the design of stationkeeping. Several stationkeeping strategiesare analysed based on the constraints from dynamical environment, actuator andautonomous navigation system. Then, an impoved control-point strategy isproposed which can provide converged results when initial injection error,navigation error and execution error are considered.Finally, a closed-loop simulation of autonomous navigation and stationkeepingstrategy is performed to verify the feasibility.