Researchers from Beihang University have developed an innovative powered descent guidance method for reusable rockets, named Endo-PDG-DR, which effectively combines disturbance rejection with optimal control. Unlike traditional systems for lunar or planetary landings, Endo-PDG-DR addresses the complexities of endoatmospheric conditions, which include nonlinear dynamics, engine thrust fluctuations, and wind disturbances. The proposed method integrates real-time nominal trajectory generation with robust feedback control to achieve adaptive optimal steering and disturbance attenuation.
By categorizing disturbances into modeled and unmodeled types, the researchers devised two distinct strategies for addressing them. Modeled disturbances are systematically incorporated into the dynamics model, while unmodeled disturbances are countered using an innovative Pseudospectral Differential Dynamic Programming method, which solves the Hamilton-Jacobi-Bellman equation to derive an optimal feedback control law. This law allows the system to adaptively optimize the trajectory while minimizing performance metrics like propellant consumption.
The research highlights the need for advancements in guidance strategies to enhance robustness, with suggested future directions including online model identification and optimal trajectory generation under constraints. This significant work was published in the Chinese Journal of Aeronautics on December 14, 2024.
