Study on the optimal trajectories of lunar soft-landing with fixed-thrust using SQP method

The Lunar Soft-landing will be the significant technique of lunar exploration mission in the future. To this technique, an optimization approach of lunar soft-landing with fixed-thrust using SQP method is presented. It made the lunar soft-landing trajectories with fixed-thrust to the discrete. At the discrete point, the continuity of motion states was regarded as the constraint conditions, then the problem of the lunar soft-landing trajectories with fixed-thrust could be translated into a nonlinear program problem. During solving this problem, all of the initial values, including the motion states and control value, had the physical meanings. So the guessing the initial values, which had no physical meanings, was avoided. Finally, it solved this problem using Sequential Quadratic Programming (SQP) method. The results of calculation and simulation indicate that application of the discrete method for problem of trajectory optimization can avoid the problem of initial value sensitivity.