This work presents a Physics-Informed Indirect Method (PIIM) that propagates the dynamics of both states and co-states backward in time for trajectory optimization problems. In the case of a Time-Optimal Soft Landing Problem (TOSLP), based on the initial co-state vector normalization technique, we show that the initial guess of the mass co-state and the numerical factor can be eliminated from the shooting procedure. As a result, the initial guess of the unknown co-states can be constrained to lie on a unit 3-D hypersphere. Then, using the PIIM allows one to exploit the physical significance of the optimal control law, which further narrows down the solution space to a unit 3-D octant sphere. Meanwhile, the analytical estimations of the fuel consumption and final time are provided. Additionally, a usually overlooked issue that results in an infeasible solution with a negative final time, is fixed by a simple remedy strategy. Consequently, the reduced solution space becomes sufficiently small to ensure fast, robust, and guaranteed convergence for the TOSLP. Then, we extend the PIIM to solve the Fuel-Optimal Soft Landing Problem (FOSLP) with a homotopy approach. The numerical simulations show that compared with the conventional indirect method with a success rate of 89.35%, it takes a shorter time for the proposed method to find the feasible solution to the FOSLP with a success rate of 100%.
Global Search for Optimal Low Thrust Spacecraft Trajectories using Diffusion Models and the Indirect Method
PhD Student, Department of Mechanical and Aerospace Engineering, Princeton University, NJ, USA（普林斯顿大学机械与航空航天工程系博士生）；Assistant Professor, Department of Mechanical and Aerospace Engineering, Princeton University, NJ, USA（普林斯顿大学机械与航空航天工程系助理教授）
Learning-Accelerated Optimization-based Trajectory Planning for Cooperative Aerial-Ground Handover Missions
Institute of Engineering and Computational Mechanics, University of Stuttgart, 70569 Stuttgart, Germany（工程与计算力学研究所，斯图加特大学，德国斯图加特70569）；Mechanical Engineering, LUT University, 53850 Lappeenranta, Finland（机械工程，卢蒂大学，芬兰拉佩恩兰塔53850）
