2013 Volume 56 Issue 3 Pages 113-120
The lunar landing stage can be divided into three phases: de-orbit, powered descent and terminal approach. Most fuel is consumed during the powered descent phase. Therefore, the optimization problem of minimum energy is typically focused on this phase. In this paper, a highly precise three-dimensional descent dynamics model is derived, and the main constraints for a manned lunar mission are presented. To solve this complex optimization problem with strict constraints, a hybrid optimization method which combines the collocation method-Gauss pseudospectral method (GPM) and shooting method is proposed. In this approach the GPM is used to provide an initial guess for the shooting method, which is then used to obtain the final optimal solution. The simulation results show that the proposed method can solve the lunar powered descent optimization problem effectively with the solution obtained satisfying all the input constraints and having high precision.