Research On Trajectory Design And Guidance Technology For Lifting Re-entry Vehicle

Due to the broad flight envelops spaning of the reentry process and the specific characteristics of the lifting reentry vehicles, it has already became the focus studies and front field among countries. This paper aims to solve the crucial problems in the trajectory optimization and reentry guidance technology, and mainly contain the following two parts:Firstly, Researches on the multiple constraints trajectory optimization have been studied as the foundation.To meet the task requirement in 3-dimensional space, the six degree of freedom motion equation of the vehicle is established in the half-speed coordinate system. To determine the safety reentry corridor of vehicle and finish the mission requirements of the gliding phase, the constraints of the trajectory design is considered, including dynamic pressure, overload, heat flow and the quasi equilibrium glide, the terminal and the control variable constraint. Under the above analysis, the mathematical model of the trajectory optimization problem of the lifting reentry vehicles is established, and the optimal trajectory is obtained by the Gauss pseudo spectral method. The optimal trajectory is obtained, which satisfies the maximum range and the equilibrium glide constraint condition respectively, and the flight performance of the vehicle is analyzed.In order to improve the efficiency of trajectory optimization, the idea of the trajectory planning is integrated into the trajectory optimization. In view of the trajectory optimization problem under the condition of the fixed end speed, The Bezier curve nominal path is used to form the constraints of the starting and the terminal position and angle. By the inverse dynamic method, the path information of the vehicle is used to influence the control input and velocity, thus the trajectory optimization problem of the infinite dimensional is transformed into the curve modeling parameter optimization problem. The rate of the trajectory optimization is improved. Furthermore, by utilize optimized parameters and the state feedback of the vehicle, and the real-time control is obtained to complete the glide guidance, and the expected end point and end speed can be guaranteed.Second, to ensure the safety flight and reduce the pressure of the guidance mission, the trajectory tracking guidance is designed.To improve the dynamic response characteristics of the system, the novel Riccati tracking guidance law is designed with the utilization of the conventional SDRE equation(SDRE). The transient and steady state performance of the system are obtained in the same time. Furthermore, the integral sliding mode theory is applied to the system with parameter variations or external disturbances. By combining the integral sliding mode theory with the novel SDRE, the optimal integral sliding mode tracking guidance law is designed, and the robustness of the system is improved.In order to improve the robustness and tracking precision of the system, a time varying sliding mode tracking guidance law is designed. Firstly, an exponential time-varying sliding mode is designed to track the nominal trajectory, and the global robustness is obtained. Furthermore, the adaptive algorithm is used to adjust the gain parameters. Finally, to ensure that the error of the system is converge to zero in finite time, adaptive polynomial finite time sliding mode is designed, and the global sliding mode dynamics is established.