Trajectory Planning Technology for Lunar Launch Window Expansion Based on Improved PSO

A guidance method based on particle swarm optimization (PSO), suitable for expanding the launch window of lunar ascent phase, is developed. Firstly, the dynamic model of Lunar lander is constructed. Then, a PSO, whose inertia and acceleration coefficient have been improved, is established to solve the problem of accurate ascent guidance. Finally, the improved algorithm is compared with a traditional one. The results show that the improved PSO can effectively meet the requirement for accuracy: the error of semi major axis is in the order of 10 meters, the error of inclination and right ascension of the ascending node (RAAN) is in the order of 0.01°. For the problem of expanding launch window of lunar ascent phase, RAAN can be transformed from coplanar launch by 10° when using improved method, which is equal to 20 hours of launch delay or advance. Compared with the traditional PSO, improved PSO has significant advantages in solving the problem of accurate lunar liftoff, its convergence is stronger and the accuracy is significantly higher.