Trajectory Design And Optimization Of Aerospace Vehicle Based On Multi-task And Multi-objective

As the combination of aviation technology and space technology, aerospace vehicle has the advantages of fast flight speed, high reuse rate, strong mobility and complete functions, such that it not only has many civilian uses, but also has high military, and may cause a new round of military revolution. Therefore, this paper focuses on the trajectory design and optimization of aerospace vehicle.In essence, trajectory optimization is regarded as an optimal control problem. For this problem, the solving ideas of model transformation and optimization calculation are proposed in this paper. And the advantages and disadvantages of different methods in each step are discussed, then further the solution procedure is given.The 3DOF motion model of aerospace vehicle is established, and they are analyzed accurately to environment model, atmospheric model, sound velocity model and gravity model affecting the the optimal trajectory precision.In this paper, the dodge-flying trajectory optimization problem for an air-based aerospace vehicle is studied. According to mission requirements, the whole flight is divided into two segments: ascent phase and cruise phase, and the ideas of modeling and optimization by step are proposed. For the traditional indirect methods, whose optimal conditions derive cumbersome and whose optimal trajectory are sensitive to the initial values, firstly the direct collocation methods are used totransfer the infinite dimensional dynamic optimal problem into finite dimensional static optimal problem, namely nonlinear programming problem (NLP). Secendly considering that the constraints of the NLP problem are complex and the feasible region is narrow, a sequential-division optimization strategy is proposed to solve the optimal problem using sequential quadratic programming (SQP), finally then the simulation and error analysis are done.The glide trajectory optimization problems for aerospace vehicle are studied, and the new model transforming method based on the Legendre pseudospectral method is developed, then further a serial hybrid optimization strategy combined genetic algorithm with SQP is designed. By calculating the safe corridors, the initial reference trajectory is obtained, which can speed up the convergence. Finally, the simulation results based on the performance of maximum range demonstrate that the Legendre pseudo-spectral method can also deal with trajectory optimization problems well, and the serial hybrid optimization strategy is efficient and feasible.