An Online Trajectory‐Planning Guidance Method for Reentry Vehicles With Bézier Curve–Based Shaping Approach

To improve the real‐time capability and adaptability of online trajectory‐planning guidance for reentry vehicles, a guidance method based on a Bézier curve shaping approach is proposed. Leveraging the inherent boundary condition satisfaction and smoothness characteristics of Bézier curves, both longitudinal and lateral guidance are designed. For lateral guidance, after nondimensionalizing the dynamic model, the ground track of the vehicle is described by Bézier curves with the help of their ability to satisfy the terminal constraints to avoid integral operations inherently. The functions of heading angle, bank angle, and aerodynamic forces about the Bézier curve parameters are derived, and according to the prescribed boundary conditions, the number of Bézier curve parameters to be determined is further reduced. Thus, the lateral guidance problem is transformed into a planning problem with a limited number of Bézier curve parameters as control variables. For longitudinal guidance, leveraging a predesigned angle‐of‐attack profile, the longitudinal dynamics model taking the Bézier curve parameters characterizing the lateral motion as the control variable is derived. Considering multiple constraints, the reentry guidance problems are transformed into optimization problems with the Bézier curve parameters characterizing the lateral motion as the control variable. The above optimization problem is then solved efficiently employing optimization algorithms. The results of simulations demonstrate that the guidance method developed in this paper significantly enhances the guidance accuracy and real‐time performance, while enhancing the smoothness of the flight trajectory and control variables.