Online Trajectory Optimization Method for Large Attitude Flip Vertical Landing of Starship-like Vehicles

An online trajectory optimization method based on convex optimization is proposed for the trajectory planning problem of large attitude flip vertical landing flight segment of a starship-like vehicle. Considering that the aerodynamic force and aerodynamic moment in the Earth landing have a large influence on the rocket flight and cannot be neglected, a planar landing motion model of a starship-like vehicle with pitching motion considering the aerodynamic influence is developed. By analyzing the constraints on its power landing process, a model of the fuel-optimal trajectory optimization problem in the landing point coordinate system is formed, and the nonconvex characteristics of the optimization model are analyzed and discussed, and a suitable sequential convexification algorithm is designed. Finally, the trajectory optimization program based on Matlab GPOPS solver is implemented for the above trajectory optimization problem, and the numerical results are analyzed and studied.