Kinematics Modeling And Steering Performance Analysis Of Four-wheel Independently Driven Manned Lunar Rover

In recent years,with the continuous development of science and technology in China,the space industry has made breakthroughs.At present,our country has realized the soft landing of the unmanned lunar rover on the lunar surface.Great achievements have been made in the first phase of the Chinese lunar exploration project,and manned lunar landing is planned in the near future.Manned exploration of the moon requires manned mobile tools with high safety and maneuverability.The independently driven wheeled skid steering vehicles have important research value in the field of manned spaceflight due to its advantages of simple structure,light weight,small steering radius and easy folding.At present,the researches on wheeled skid steering vehicles mainly focuses on the contact relationship analysis between wheels and ground,controlling steering trajectory,steering dynamics.There are relatively few studies focus on the analysis of calculating the steering trajectory of wheeled skid steering vehicles.In view of the fact that there are few studies on the calculation and prediction of steering trajectory of wheeled skid steering vehicles,a three-degree-of-freedom steering kinematic model of four-wheel skid steering vehicles is established.The correctness of the kinematic model is verified by comparing the results of simulation and calculation.The main research content of this paper are:1)Based on the design concepts of light weight,folding and high reliability in the space exploring field,a 3d model of four-wheel independently driven skid steering manned lunar rover was established.According to the feasibility analysis of steering and the analysis about stress of the key parts,the structural optimization and its rationality analysis of the vehicle was made.2)The relationship between the direction of friction and the rotation speed of each wheel was analyzed,a mathematical model was established to describe the relationship between them.The resultant force of each wheel is simplified to the geometric center of the vehicle,and a three-degree-of-freedom steering kinematic model is established to describe the steering process of the vehicle.The correctness of the steering kinematics model is verified by comparing theoretical calculation with simulation analysis.3)Based on the established steering kinematics model,the control-variable method is used to analyze the influence of many key parameters on four-wheel skid steering vehicles.The key parameters includes lateral wheelbase,longitudinal wheelbase,wheel radius and so on.4)In order to compare the results of kinematic response obtained by simulation and calculation,many series of data from simulation and calculation was exported based on ADAMS/SIMULINK Co-simulation platform.The differences between the theoretical results and the simulation results were analyzed in many conditions.The comparison results show that the kinematic model used to describe the vehicle steering process in this paper has a small error compared to simulation and the established kinematic model can correctly analyze process of four-wheel skid steering vehicles.