Design Of Lunar Soft Landing Cushion Foot And Simulation Study On Landing Cushioning Performance

In 2004,China launched the Chang’e Project,a lunar detection project in which soft landing is the basis for lunar detection.The buffer foot,as a component that interacts directly with the lunar soil,is the key to the successful soft landing of the probe.The probe absorbs the landing impact energy through the buffer mechanism in the buffer foot,thereby protecting the precision instruments in the probe.This paper proposes a cushioned foot that can be adapted to the lunar environment,is reusable and can be attitude adjusted after lunar landing,and investigates the dynamics of the cushioned foot.This paper compares and analyses the airbag,damped and variable form cushioning mechanisms in the probe and selects a mechanical spring damped cushion as the cushioning mechanism according to the requirements to design an open and lightweight spring damped cushion.The maximum working load and stiffness of the spring-damped buffer are calculated as the theoretical basis for the simulation,and then the dynamics of the spring-damped buffer is analyzed using ANSYS to ensure that the spring-damped buffer will not generate self-oscillation during soft landing of the probe,thus affecting the buffering effect.The hemispherical foot was chosen as the foot end configuration of the cushion foot,and the structure of the hemispherical foot end was designed to provide shock absorption during soft landing.The structure of the hemispherical foot is simplified and a Bekker stress model of the foot and the lunar soil is developed.The normal force required for the foot to be completely sunk into the lunar soil and the normal force required for the foot to be incompletely sunk into the lunar soil are calculated by combining the mechanical parameters of the lunar soil.A reliability analysis of the key components of the hemispherical foot end was carried out to determine the factors affecting the structural reliability of the hemispherical foot end.The Six Sigma module in ANSYS was used to solve for the reliability of the hemispherical foot end.The overall simulation model of the probe and the flexible lunar soil model were established in ADAMS to analyse the landing attitude and landing conditions of the probe during the soft landing process,and to determine the influence of different spring damping coefficients,horizontal velocity,lunar surface slope,pitch angle,yaw angle and other factors on the landing stability.The best value of spring damping coefficient,the lower the horizontal velocity,the better the stability of the probe,the best stability of the buffer foot 2-2 landing(yaw angle 22.5°),the lower the slope of the lunar surface,the better the stability of the landing,and the best possible soft landing in a flat landing area.The stability performance of the cushioned foot during soft landing studied in this paper will provide some theoretical basis for subsequent research on probe walking.