Controlling lunar lander in powered descending phase

The requirement for controlling lunar lander in the powered descending phase is analyzed in the paper. With suboptimal minimum fuel considered first, the expected non-iterative calculation formulas of the attitude angles are acquired. The explicit guidance project in relevance with the state variables and terminal restrict are deduced. According to deflection between the real attitude angles and the desired attitude angles, the attitude tracking system is designed by adopting the method of exponent reaching law and chattering reducing of boundary layers based on variable structure control with sliding mode. The simulation results show that the control system can complete flying mission in the powered descending phase, and has good robustness and adaptability as well.