Nonlinear optimal control for the soft landing of lunar landers

This paper deal with the soft landing of the lunar lander. The design of the controller and guidance law had been completed in two steps. At first, having utilized a differential homeomorphic transformation and a nonlinear input compensation, we transformed 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 were given. In the second steps, making use of the H_∞control approach, we designed 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.