Research On Trajectory Optimization And Guidance Method For The Booster Of Launching Vehicle

With the rapid development of aerospace technology and because of high military and civilian value,small launch vehicles have become a hot spot in international researc h in recent years.In order to ensure launch vehicles can arrive their destination successfully in the complex and variable environment to complete the designated delivery mission,researches on trajectory optimization and guidance methods is particularly important.This thesis focuses on the optimization and guidance of the trajectory of the launch vehicle's booster segment,and has completed the following works:Firstly,the research background of small launch vehicle and the research significance of online trajectory planning are introduced.The principle characteristics and application examples of various trajectory optimization and guidance methods existing at home and abroad are reviewed and compiled,which provides reference for the research method and application analysis.For this subject,the flight process of the boosting segment is modeled according to the dynamics principle while the corresponding three-degree-of-freedom nonlinear mathematical equations are obtained,which provides the model basis for the application simulation of the subsequent methods.Secondly,the optimization of the trajectory of the climber segment of the aircraft based on particle swarm optimization is studied.The high-speed aircraft trajectory optimization problem is firstly transformed into a nonlinear programming problem by Chebyshev's direct shooting method.Then,by introducing the "variation" and "multi-strategy" ideas to improve the particle swarm optimization algorithm,a multi-strategy co-evolutionary particle swarm optimization algorithm based on differential future algorithm is proposed.The rocket boosting segment is simulated and analyzed to verify this improved algorithm.The result shows that the improved group algorithm optimization displays better.Then,using the optimized trajectory as the nominal trajectory and based on the idea of rolling time domain,the tracking guidance of the boosting segment is transformed into the one-dimensional variable rolling time domain suboptimal problem in the finite time domain.In each guidance cycle,a chaotic optimization search is performed near the nominal value for the guidance command in the finite time domain.In the mean time,dynamic pressure,heat flow and angle of attack constraints existing during the flight are taking into consideration to obtain a feasible control sequence.The numerical simulation results in the rocket boosting section show that the tracking guidance method based on rolling chaos optimization has higher precision and speed.Simultaneously,it has certain anti-interference ability to the uncertainty occurs during the flight process.In order to adapt to the uncertainty of the environment and provide more maneuverability and flexibility during the flight,an improved SQP trajectory rapid planning method based on the surrogate model is designed.Also,to meet the high requirements of trajectory online planning speed,this thesis improves the traditional SQP algorithm on its sensitivity to the initial values.Instead,the initial value near the optimal solution will be provided by the surrogate model,which can reduce the iteration and accelerate the algorithm convergence.At the same time,to ensure that the algorithm has certain adjustment ability to the environmental uncertainty,the deviation correc tion of the model is performed on the surrogate model.By numerical simulation and comparison with the traditional SQP method and the tracking guidance method proposed in this thesis,the effectiveness,rapidity and anti-interference ability of the algorithm are verified.Finally,there is a summary of this thesis.Analysis of the lack of current research work is proposed.Also,the direction of further research in high-speed aircraft trajectory optimization and tracking has been advised in the end of the thesis.