Reusable Rocket Reentry Trajectory Optimization And Fault Tolerant Guidance

Reusable launch vehicle is the main means of transportation to and from space in the future because of its economy and timeliness.The environment of reentry process of reusable launch vehicle is complex,the flight conditions are bad,and the actuator is prone to failure.So in this paper,trajectory optimization and fault-tolerant guidance are studied for each flight segment of reusable launch vehicle.Specific research contents includeFirstly,the background and significance of the research are summarized,and the development status of reusable launch vehicle at home and abroad is introduced.The research status of trajectory optimization method and fault-tolerant guidance method is summarized.Secondly,based on the analysis of the characteristics and specific flight stages of reusable launch vehicle,the dynamic model of reusable launch vehicle is established,which provides the basis for the following research work.Thirdly,two trajectory optimization methods are used to optimize the trajectory of the reentry stage: The first method is the Gauss pseudospectral method in the direct method.In this paper,the Gauss pseudospectral method is used to transform the dynamic optimization problem into the nonlinear programming problem,and the reentry trajectory of reusable launch vehicle is optimized with the fuel optimization as the performance index.The second method is Newton iterative method,which is an on-line trajectory optimization method.In this paper,the reentry trajectory of reusable launch vehicle is optimized with the same performance index of fuel optimization.The feasibility of the two methods is verified.Finally,the advantages and disadvantages of the two trajectory optimization methods are given.Fourth,based on the optimal trajectory given by Newton iteration method,different guidance methods are used in different flight stages,limited thrust guidance is used in braking deceleration stage,and iterative guidance is used in pneumatic deceleration stage.Finally,the effectiveness of these two methods for trajectory tracking is verified by simulation.Fifthly,aiming at the fault of reusable launch vehicle's reentry engine and grid rudder,the Newton iterative method and iterative guidance are improved.The fault-tolerant online trajectory optimization algorithm and fau lt-tolerant iterative guidance algorithm are designed to improve the reusable launch vehicle's ability to deal with the fault during the reentry process.To sum up,this paper will study the dynamic model,trajectory optimization and fault-tolerant guidance of reusable launch vehicle reentry phase,and put forward relevant trajectory optimization and fault-tolerant guidance methods,providing theoretical reference for engineering application.