Ascent Phase Trajectory Optimization for Near Space Vehicle Based on Gauss Pseudospectral Method

Considering the impacts of the changes,such as the density of atmospheric,the speed of sound,the thrust and the earth gravity on flight trajectory,a more realistic near space vehicle ascent minimum fuel-consumption trajectory optimization problem is studied. Aiming at the difficulties of the problem in processing of aerodynamic data as well as optimization solving,a strategy based on the Gauss pseudospectral method is proposed in the paper. Firstly,high-accuracy fitting of aerodynamic parameters is achieved by designing a fitting model according to the characteristics of aerodynamic data. Secondly,to avoid the drawback of indirect methods and traditional direct methods,the combination of Gauss pseudospectral method and the sequential quadratic programming is proposed to solve the trajectory optimization problem with boundary and acceleration constraints. Finally,simulation results illustrate that the optimal trajectory with the accuracy of 10-4～10-6 can be generated within 5.83 s in more realistic environment.