Study On Space Optimal Rendezvous Trajectory Planning Approach

Rendezvous and docking technology is essential in space-assembly, space-succor, outer space-exploration etc., and is a key technology for the second step of China manned spaceflight project. Rendezvous trajectory planning is a critical problem in rendezvous and docking technology. For the purpose of solving the critical engineering application problems and further developing the new theory and methods, this dissertation studies the optimal rendezvous trajectory with perturbations and path constraints planning problem, the multiobjective rendezvous trajectory planning problem, the robust optimal rendezvous trajectory planning problem and the real-time trajectory planning problem with considering uncertainties. The main results achieved in this dissertation are summarized as follows.The optimal planning approaches for rendezvous trajectory with trajectory perturbations and path constraints are developed. 1) A hybrid approach combining the global search ability of genetic algorithm and the high convergence rate of SQP, together with the simplified analytical propagator and the high-fidelity mathematical propagator is proposed to solve the perturbed and path-constrained multi-impulse fuel-optimal rendezvous problem. 2) An interactive optimization approach using the evolutionary algorithm, the Lambert rendezvous algorithm and the Primer vector theory is proposed to optimize a rendezvous trajectory with the optimal number of impulses. 3) The design of a rendezvous phasing strategy with special-point maneuvers is formulated as a mixed integer and continuous nonlinear programming problem. A hybrid approach combining an integer-coded genetic algorithm with Newton's method is proposed for solving this problem. Three improvements including the infeasible solution return, the memory database and renewing the initial guess are imposed on the hybrid approach to make it more efficient and robust. 4) A new multiple-revolution Lambert algorithm is proposed, and an optimization model is formulated for the design of a rendezvous phasing strategy with combined maneuvers, and a global optimization approach based on a parallel simulated annealing using simplex method is proposed. The global convergence ability, high efficience and robustness of these four proposed optimization approaches are testified by solving the analytical problems and the practical problems.The optimal multiple-objective rendezous trajectory planning theory, methods and approaches are studied and proposed. 1) A performance index related to rendezvous trajectory passive safety is defined and a semi-theoretical model for calculating this safety performance index is provided. 2) Based on the Clohessy-Wiltshire linearized rendezouvs equations and two-body Lambert rendezvous equations, the three-objective optimization models including the minimum characteristic velocity, the minimum time of flight and the maximum safety performance index are respectively formualted, the nondominated sorting genetic algorithm(NSGA-â…¡) is employed to obtain the Pareto solution set. The optimizaiton results can quickly demonstrate the tradeoffs between the whole performace indexes of a rendezvous trajectory. 3) The optimization approach using the physical programming, the Lambert rendezvous algorithm and the simulated annealing for the multi-objective optimization design of nonlinear perturbed rendezvous is proposed, the designer preferred solution which can be directly applied to mission plan is obtained.The robust optimal rendezous trajectory with uncertainties planning theory, methods and approaches are studied and proposed. 1) One robustness performance index of a rendezvous trajectory with uncertainty is defined, and one covariance analysis method for nonlinear rendezvous uncertainty analysis is proposed. 2) Based on the Clohessy-Wiltshire linearized rendezouvs equations and the two-body rendezvous equations, a two-objective optimization model including the minimum characteristic velocity and the minimum robustness performance index are formuated, the NSGA-â…¡is employed to obtain the Pareto solution set. The Pareto optimality of the obtained solutions is testified by comparing with the fuel-optimal and robustness-optimal solutions. 3) The robustness performance index is introduced into the multi-objecitve rendezvous trajectory planning. The results can quickly demonstrate the tradeoffs between the whole performance indexes of a rendezvous trajectory with uncertainty.The realtime rendezous trajectory planning approaches are studied and provided. 1) The trajectory guidance algorithm which considers trajectory perturbations for autonomous rendezvous is proposed based on the Lambert algorithm. 2) The real-time planning approach for phasing rendezvous trajectory maneuvers, including the special-point maneuvers real-time planning approach and the combined maneuvers real-time planning approach using the near circular deviation equations, are developed. 3) A rendezvous trajectory planning software which integrates the theoretical achievements of this dissertation is developed for engineering application.This dissertation expands the research domain of the current rendezvous trajectory planning by developing the optimal multiple-objective and robust optimal rendezous trajectory planning theory, methods and approaches, which have some theoretical significance and also provide new design tools for comprehensive performace index optimization design of a rendezvous trajectory. The proposed complex rendezvous trajectory planning approach, the real-time rendezvous planning approach and the developed rendezvous trajectory planning software solve the ctritical engineering problems, which have high application value in China manned spaceflight project and other space application projects.