Design And Optimization Of Low-Thrust Interplanetary Transfer Trajectory

The new high tide of technology research and plan execution for deep space exploration has arrived in the 21st century. The outer planet exploration, re-entry Moon and small celestial body exploration missions have been implemented or listed in the timetable. In interplanetary exploration missions, especially in outer planet exploration missions, the tremendous increment of velocity is needed to finish the transfers; hence, the application of low-thrust propulsion system, which has high specific impulse, has been widely concerned. The application of low-thrust propulsion system increases the mass percentage of payloads, and economizes the cost of mission, however, the application of low-thrust propulsion system brought up a new challenge for the technology of trajectory design.With the supports of the Tenth Five-Year 863 Program'Autonomy Technology of Deep Space Exploration and Its Simulation and Demonstration System','Investigation on Entry Orbit Design and Optimization of Interplanetary Surperhighway', National Natural Science Foundation of China'Investigation on Mechanism and Optimal Method of transfer Trajectory for Deep Space Exploration', this dissertation studies the design and optimization methods of low-thrust trajectory, throughly. The main contents of this dissertation are as follows:For the design and optimization of low-thrust interplanetary cruise segment, two types of design method are presented. There are"nominal trajectory method", which is used for initial design and performance index estimate, and"GA-hybrid method", which is utilized for the optimization of precise trajectory. By introducing the concept of nominal trajectory, and transforming the optimal models with the characters of Kepler orbit, nominal trajectory method increases the speed of computing, avoids the bad convergence, and this method could be used for initial design and performance estimate. Based on the analysis of the sensitivity of costate equations, GA-hybrid method utilizes the global optimal character of GA and the effect of random annealing punishment function in the treatment of constraints to optimize the complicated low-thrust interplanetary cruise segment.For the design of planetary transfer trajectory with low-thrust propulsion system, after analyzing the dynamical character and combining the concept of Lyapunov feedback control, a novel design mothed of planetary transfer trajectory based Lyapunov local optimal feedback control law has been presented. First, the utility which is caused when the thrust changes the single element has been analysied. Second, Lyapunov function has been set based on the forecited analysis, then the semi-analytical expressions of local optimal thrust angles has been derived. Finally, weights of Lyapunov function have been adjusted by parameter optimization. Numeral example has shown that if the weights are choosen appropriately, the sub-optimal solution will close to the optimal solution. This method could solve low-thrust trajectory under constraint of switch function without any priori information, and low-thrust escape and capture trajectory.For the concept of interplanetary superhighway (IPS) in recent year, low-thrust IPS scenario has been presented by combining IPS technology and low-thrust propulsion technology. By utilizing dynamical system theory, the invariant manifold connected with libration points and periodic orbit has been analysed, and its surface structure has been studied by Poincarémap, then ubiety between manifold associated with libration point and manifold associated with periodic orbit has been educed, thus potential IPS channels between celestial bodies in solar system has been analysed. A searching method of exploration opportunity of IPS transfer trajectory has been given combining with nominal trajectory method, then based on this method, Crusie segment of low-thrust IPS trajectory could be optimized. For the design of escape and capture trajectory in low-thrust IPS transfer, namely the design of low-thrust trajectory between parking orbit and periodic orbit, the thrust arc could be patched to coast arc by drawing Position-velocity Poincarésection, then by combining the method of Lyapunov feedback control law, the design and optimization of low-thrut IPS escape and capture trajectory have been realized, thus the design of whole low-thrust IPS trajectory from parking orbit to target orbit has been completed.In this dissertation, based on GA-hybrid method in the design of interplanetary cruise segment, the Lyapunov local optimal feedback control law in the design of planetary trajectory and the optimization method in low-thrust IPS transfer trajectory, taking the earth-venus exploration mission as an example, the scenarios of various interplanetary low-thrust missions have been listed and analysed, thoroughly. First, 6 kinds of basic trajectory scenario have been given, and 3 new trajectory scenario of these 6 have been entirely designed and optimized, data of cruise segment, escape and capture segment, strategy of control, time of flight and the consumption of propellant have been obtained. Second, Analysing the distance and included angle informations from the views of payload, structure of Probe, constraint of instruments and measure and control system, respectively. Based on these design and analysis, the effectiveness of design and optimization methods, which are given in this dissertation, is validated.