Trajectory Optimization and Guidance Strategy for TBCC Powered Vehicles Considering Mode Transition Point

To address the challenges of complex propulsion mode transition, strong nonlinearity, and stringent path constraints during the ascent phase of Turbine-Based Combined Cycle (TBCC) powered vehicles, this paper presents an integrated trajectory optimization and guidance method that takes into account the optimization of propulsion mode transition points. During the trajectory optimization phase, a nonlinear optimal control problem is formulated where the altitude and velocity at the mode transition point are introduced as optimization variables. These are jointly optimized along with dynamic pressure, overload, and heat flux constraints to obtain a globally feasible solution. Simulation results demonstrate that, in comparison with traditional fixed mode transition strategies, the proposed method achieves approximately 2%–5% fuel savings and shortens the ascent duration while satisfying all path constraints. Furthermore, a Linear Quadratic Regulator (LQR) is designed to achieve real-time feedback control of the optimal trajectory. Further Monte Carlo simulations confirm that the proposed guidance strategy maintains robust performance under uncertain environments.