Bionic Optimization And Endurance Experiments Of Wheels For Mars Rovers

The surface of Mars is covered with gravels and stones besides soft soil,which poses a severe test for the endurance of the metallic Mars rover wheels.Therefore,in the premise of limiting mass,structure and material,the optimization of wheel's surface and the improvement of endurance is necessary to explore Mars.The main research contents are as follows:The selection of bionic prototypes and the design of bionic wheel surfaces.Four kinds of creatures(clam shell,dung beetle,Manis Pentadactyla and chlamys farreri)which are good at wear resistance were selected,then the convexes,concaves,ridges and scale-like forms on the surfaces of these four creatures were applied to the design of Mars rover wheels.The endurance experiments study of bionic wheels.A test bed was established to study the durability of these four kinds of bionic wheels.The test was separated to 3 steps,and the results showed that the forms of concave and ridge have no wear resistance characteristics compared with original wheel.Convex forms exhibited the greatest wear resistance and drag reduction during abrasion with quartz sand.The wear mass and energy consumption were reduced by 46% and 26%,respectively,compared with those of the original wheel.On bedrock and course quartz sand,the scale-like form reduced the wear mass per hour by 67.5% compared with that of original wheel.The discrete element analysis of bionic wheels.In order to optimize the structure and seek the best forms of elements,the discrete element simulation(DEM)system of wheel-soil was developed,and 3D DEM analysis and soil bin tests were conducted.The result showed that the mass of convex and scale-like forms increased by 5.4% and 17%,and tangential cumulative force reduced by 40% and 70% on average respectively.Simulations showed the significant increase of durability.On the other hand,tangential cumulative force of concave and ridges increased by over50% on average and the results were not prospective.Orthogonal optimization of scale like structure.Considering the integrity of scale-like forms,the proportion and height were regarded as the factors to be optimize and nine kinds of structures were designed.According to comparing cumulative force and cloud maps,the simulation indicated that the scale-like forms had the best durability characteristics when the scale was 1.4 times of the original scale and the height was 1mm.Endurance study and DEM simulation show that the durability of wheels can be improved through bionic optimization method under the condition of constraining mass.The results can provide basis and reference for design and optimization of Mars rover's wheel surface.