Optimal Reentry Guidance For Hypersonic Vehicles

In this paper, it chooses the X-33 aircraft as the research object. Firstly, according to the characteristics of the reentry process, it creates the reentry equations of motion in the half-speed coordinate system. It gives the objective function that makes the errors of the height, longitude and latitude minimum at the end of time. Meanwhile it analyses the constraints of the overload, dynamic pressure and heating rate. Finally it establishes the reentry corridor of the height-speed profile.This paper introduces the basic principles of the Gaussian pseudo-spectral method (GPM) and transforms the optimal control problems into solving the parametric problem of state variables and control variables. Ultimately it analyses the convergence speed and accuracy of the Gaussian pseudo-spectral method (GPM) when solving optimal control problems.During the design of aircraft trajectory optimization, it draws the curves of the flight path angle, longitude, latitude and other state variables and gives the errors at the terminal time through the simulation analysis. Meanwhile it analyses the effects of the initial estimates of the value, the number of collocation points on the trajectory optimization.This paper analyzes the errors at the end point in the presence of aerodynamic coefficients errors and initial errors through the simulation analysis. At the same time it gives the curves of the actual trajectory and the reference trajectory. Ultimately it uses the linear quadratic regulator (LQR) to track the reference trajectory and analyses its robust characteristics.