Nonlinear optimal control for the soft landing of lunar lander

This paper deals with the soft landing of the lunar lander. The design of the controller and guidance law has been completed in two steps. At first, utilizing a differential homeomorphic transformation and a nonlinear input compensation, we transform the dynamics description of the lunar lander into a linear system. Then, based on the Yula equation of the classic optimal control method, a designing procedure and the general explicit solution of the normal guidance law is given. In the second steps, making use of H_infincontrol approach, we design a feedback controller for the uncertainties and disturbance such that the real system can track the normal orbit. At last, simulation results illustrate the feasibility and advantage of our approach