Modelling Of Flexible Metal Wheels For Planetary Rover On Deformable Terrain

The planetary rover is one of the most important detectors for performing planetary exploration missions.The wheel is in direct contact with the deformable terrain,and it plays the role of bearing,driving,steering,towing and adapting to the ground.It is one of the most critical components of the planetary mobile system.The flexible wheel is the main direction of the development of China's future planetary rover wheels with its excellent performance,but it is the main form of the planetary rover wheel due to the constraints of material,environment,rigidity and quality.Therefore,establishing a model of the relationship between the flexible metal wheel and the deformable terrain interaction and analyzing it is essential to improve the maneuverability,stability and smoothness of the planetary rover.In this paper,a thin-walled ring flexible metal wheel is designed and processed,and the subsidence,drawbar pull,torque and traction efficiency of the smooth flexible wheel and the flexible wheel and rigid wheel with wheel thorn are compared and analyzed by soil test.The soil test results show that the amount of subsidence of the smooth flexible wheel and the pulley flexible wheel is reduced by 39.95 % and 41.47 % compared with the rigid wheel.The traction force of the smooth elastic wheel and the wheeled flexible wheel hook increased by 47.53 % and 102.11 % compared with the rigid wheel.The smooth flexible wheel and the wheeled flexible wheel torque increased by 4.20 % and 27.66 % compared with the rigid wheel.The traction efficiency of the smooth flexible wheel and the wheeled flexible wheel increased by 28.06% and 49.13% compared with the rigid wheel.The test results show that the flexible wheel has good traction performance compared with the rigid wheel.The deformation characteristics of flexible wheel are analyzed,and the geometric model of flexible wheel deformation is established.On this basis,a static model of the interaction between flexible wheel and the deformable terrain is established,and the average relative error of the subsidence model is 6.30 %.This paper focuses on the interaction between flexible wheel and the deformable terrain,and deduces the interaction model between flexible wheel and the deformable terrain,which are flexible wheel drawbar pull model,flexible wheel load model,flexible wheel torque model and flexible wheel dynamic subsidence model.The established model is validated by experimental data.The test results show that the mean square root error of load model is 17.61 %,9.51 % and 28.27 % respectively under the conditions of load 40 N,80 N and 120 N.Under the conditions of load 40 N,80 N and 120 N,the mean square root error of the drawbar pull model is 23.32 %,13.99 % and 17.55 %,respectively.Under the conditions of load 40 N,80 N and 120 N,the mean square root errors of the torque model are 10.87 %,6.50 % and 4.76 %,respectively.Finally,Matlab software is used to compile the simulation analysis software to calculate the interaction between flexible wheel and the deformable terrain.On this basis,the influence of the variation of the mechanical parameters,the friction modulus,the deformation index,the cohesion,the internal friction angle,the shear deformation modulus,the width of the flexible wheel parameters,the wheel diameter,the load and the flexible deformation coefficient on the traction performance of the deformable terrain is analyzed by simulation.The above research can lay a foundation for the evaluation of the flexible wheel design,the interaction of the wheel-terrain and the traction passability of the planet rover.