On-board High Reliable Reentry Trajectory Design And Real-time Guidance

Reentry trajectory design and guidance law design are two critical technologies of reentry guidance for aero vehicles. Under the background of reentry mission requirements of lifting vehicles, high reliable trajectory on board planning and real-time guidance law design for Common Aero Vehicle (CAV) are presented in this project. In reentry trajectory design, the angle of attack and bank angle are designed respectively:To solve the problem of the lack of quantitative basis for the angle of attack, firstly, a new function of velocity and angle of attack is presented considering with the experience in the space shuttle reentry angle of attack and the angle of attack date related to the maximum lift-drag ratio, and the optimal parameters are determined. Then design a Parallel Genetic Algorithm (PGA) in two levels of population grouping and repeating the same population evolution independently to improve the computational efficiency. Finally, offline optimal design the angle of attack with the objective functions of longest range and farthest lateral range respectively; To slove the problems that the planning trajectory is seriously ups and downs and the bank angle boundary is inaccurate in the application of the on-board fast bank angle planning method with the core of Quasi Equilibrium Gliding Conditions (QEGC), a method is presented that using the bank angle which makes the rate of flight angle zero as the initial value of each on-board bank angle planning in the early quasi equilibrium gliding stage to avoid the QEGC being destroyed, and to ensure the high reliability of reentry trajectory and suppress the ups and downs. In reentry guidance law design, longitudinal and lateral guidance laws are designed respectively:Using nominal trajectory guidance method, LQR guidance law is designed to tracking longitudinal reentry trajectory; Using bank angle reversing method to realize lateral reentry guidance. In consideration of the conditions of uncertainty, multi-target reentry mission and changed-target reentry mission are simulated. The simulation results show that the high reliable reentry trajectory on board planning and real-time guidance program meet the reentry mission requirements. The research results can provide valuable theoretical guidance for the general design of reentry mission and reentry guidance scheme of lifting vehicle.