Applications of homotopic approach in variable-specific-impulse low-thrust trajectory optimization

Homotopic approach can greatly reduce the difficulty of solving optimal control problems. Although the technology of solving fuel-optimal problem by starting from the related energy-optimal one is widely used in constant-specific-impulse low-thrust trajectory optimization, it is no longer applicable for variable-specific-impulse problems. For the variable-specific-impulse low-thrust trajectory optimization, the homotopic variable-specific-impulse thrust model is established by proposing a cubic function of thrust as homotopic function, and then the problem can be efficiently solved by homotopic alternate algorithm. The results demonstrate that this technique can improve the probability and efficiency of finding optimal solution.