Trajectory Optimization Method For A Booster Vehicle

The motion model of the booster rocket and other aircraft ca n be regarded as a trajectory model of the vehicle with a boost. The optimization design of the ascent trajectory is to satisfy the constraints such as velocity and altitude of the aircraft in the scheduled orbit. In order to meet the mission with a range or fuel consumption indicators for planning at the same time, it needs to find a reasonable and more superior flight trajectory. And the boost phase often has a variety of perturbation factors. So how to modify the impact of the perturbation is also a pro blem we need to consider. In this paper, we will focus on the two problems of the ascent trajectory optimization method and the perturbation correction method.First, the aircraft model in the boost phase is established. The definition of several kinds of coordinate system and the transformations between them are introduced. The various forces during the flight are analyzed. The kinematics and dynamics equations of the three degree of freedom of the vehicle are derived. Based on the characteristics of the problem, the change of mass and thrust in the multistage boost process is presented. The establishment of the boost phase model provides the basis and foundation for the following research.Then the optimization method of ascending trajectory is mainly stud ied. First, the numerical method of Gauss Pseudospectral Method is selected as the optimization strategy. Gauss Pseudospectral Method is introduced and the method is used to deal with this problem for discretization. Second, the angle of attack flight program is designed based on the angle of attack design rules and the selection principle and combined with the model aircraft flight characteristics. Thirdly, Gauss Pseudospectral Method is used for finding the optimization solution vector which satisfies the constraints. The solution is the angle of attack curve. The obtained results are brought into the motion model of the differential equation s, and the rationality and optimality of the solution are analyzed. Fourthly, an optimization strategy based on pitch angle of program is also given. The results are compared with the angle of attack strategy. It shows that the strategy also has the validity and the rationality.At last, it is researched that how to make the actual trajectory closer to the standard trajectory in order to satisfy the constraints under the condition of several kinds of perturbations. In this paper, a method for real-time calculation of guidance coefficients is adopted. The expression of the guidance coefficient is derived. The modified result of the deviation caused by perturbation is given. By comparing the state variables before and after the modification, the rationality of the perturbation guidance is explained and the error analysis is given.