Abstract: The reusable launch vehicle has an aerodynamic shape with a high lift-drag ratio. The entry trajectory planning based on the 3-D profile can take full advantage of the inherent maneuvering ability of the vehicle. However, the heavy computational burden restricts the application of the 3-D profile planning method. To improve the computational efficiency, this paper proposes an entry trajectory planning method based on 3-D profile via convex optimization. The characteristics of dynamic equations are first analyzed, and the original non-convex trajectory planning problem is transformed into a convex optimization problem using convexification techniques such as the definition of new controls, constraint relaxation, and successive linearization. The command solution step is then inserted into the sequential convex optimization algorithm proposed in this paper. A feasible solution is obtained by solving iteratively the convex sub-problem. In the simulation experiments, the high solution accuracy and the determined convergence of the proposed method are demonstrated, and fully utilizing the maneuvering ability. Compared with the pseudospectral method, the proposed method has a significant advantage in computational efficiency.

Key words: convex optimization, 3-D profile, trajectory planning, command solution, reusable launch vehicles