Overview of Trajectory Optimization Techniques

This chapter aims to broadly review the state-of-the-art development in spacecraft trajectory optimization problems and optimal control methods. Specifically, the main focus will be on the recently proposed optimization methods that have been utilized in constrained trajectory optimization problems and multi-objective trajectory optimization problems. An overview regarding the development of optimal control methods is first introduced. Following that, various optimization methods that can be effective for solving spacecraft trajectory planning problems are reviewed, including the gradient-based methods, the convexification-based methods, the evolutionary/metaheuristic methods, and the dynamic programming-based methods. In addition, a special focus will be given on the recent applications of the optimized trajectory. Finally, the multi-objective spacecraft trajectory optimization problem, together with different classes of multi-objective optimization algorithms, is briefly outlined at the end of the chapter.