Predictor-Corrector Reentry Guidance For Hypersonic Vehicles

The lifting hypersonic vehicle has a high maneuverablity for the long-range precise strike mission. Due to the reentry environmental complexity and the trajectory's nonlinearity and hard constraints, it is difficult to design a guidance law with high accuracy and robustness. In order to develop reentry guidance technology of the lifting hypersonic vehicle, based on the Common Aero Vehicle(CAV-H), this dissertation designs a guidance law using the predictor-corrector algorithm.First, according to the character of reentry process, this dissertation builds the 3DOF equations of motion and analyzes the path constrains.In order to make the simulation close to reality, an improved aerodynamic model as a function of velocity and angle of attack is identified based on aero database. To illustrate the accuracy, the comparison with the commen model is made.By using the improved aerodynamic model, the reentry corridor and the trajectory in initial descent are simulated. The changes of them under different models are also analyzed. To enforce the path contrains on designing the guidance law, an indirect inforcement method is utilized to convert the path constraints into control variables'constraints.The process of designing the guidance law is divided into two phases in order to seek for high impact point precision. In phase I, the predictor-corrector using downrange is applied in longitudinal guidance, and in lateral guidance, the crossrange threshold is designed to constrain the vehicle to fly to the destination approximately. In phase II, the height is used in the predictor-corrector for longitudinal guidance, and the lateral crossrange threshold is designed to make the vehicle reach the destination. Finally, the simulations confirm that the vehicle can reach the same destination with different initial conditions and meet the intended accuracy.