Research On Mars Landing Guidance Design For Powered Descent Phase

With the development of the human universal detection,many countries have completed diverse deep space exploration activities.Among them,Mars exploration has been developed in a massive duty and deep layers phase.For a Mars landing mission,unknown Martian atmosphere,complex Martian terrain and valuable space for the fuel lead to a high demand for the guidance design.In the final stage of the whole landing mission,the engine should provide reverse thrusts to slow down the lander,and this phase is called powered descent phase.As the final stage,the powered decent phase plays an extraordinarily important role in the landing performance.This paper takes the disturbance caused by the Martian atmosphere and dust storms and the fast landing demand into consideration,as well as the complex terrain and the significant communicational del ay caused by the long distance between the earth and the Mars.This paper focuses on the Mars landing guidance design problem for the powered descent phase,and conains the following contents:This dissertation aims at the problem of the massive calculational amount of the fuel optimal guidance and proposes two reaching law based guidance schemes.The proposed guidance can make the lander track the desired trajectory rapidly and reduce the computional amount as well as guarantee the fuel efficiency.This pa per also provides the upper bound of the whole convergence time and the theoretical proof of the stabilization,and the analysis of the robustness.This dissertation amis at the disturbance caused by Martian atmosphere and dust storm,etc.,which damage the landing accuracy and even lead the whole landing mission to a failure result.This dissertation proposes three guidance schemes based on the fixed time stabilization method to endure the fast landing.This dissertation also gives a new theorem called practical fixed time stabilization and proposes Mars landing guidance based on this theorem,which gives the upper bound of the final landing errors based on the upper bound of the disturbance.This dissertation aims at the complex terrain and the collision problem caused by the classical guidance,and proposes a position-based ZEM/ZEV optimal feedback guidance and a position-velocity-based ZEM/ZEV optimal feedback guidance,which can avoid collisions with the Martian surface and in the meantime,the fuel effiency can be ensured.This dissertation provides the way to design the performance index and the way to get the guidance,and analyzes the strategy of the proposed guidance.This dissertation aims at the multiple constraints during the powered descent phase,including the position constraint,the velocity constraints and the maximum thrust output,etc.,and design the landing guidance based on model predictive control method.This dissertation designs velocity-free guidance and disturbance information free method.The proposed guidance can satisfy multiple constraints and be robust against disturbances.