Research On Travelling Environment Simulation And Ruts Of Lunar Rover

“Jade Rabbit” lunar rover patroled and surveyed on lunar terrain was one of the mainscientific goals in the stage Ⅱ of "Chang’ E project" lunar exploration missions. As thetrafficability of lunar terrain was low, rover sank deeply and slipped seriously when movingon lunar terrain. For evaluating the mobility of lunar rover, estimating the trafficability oflunar surface, then guiding path planning for rover, keeping rover patrol and survey safety,the main content of this paper are shown as followed:Builded lunar terrain in order to test the lunar rover in the infield, mainly includedpreparation for the morphology of terrain, the physical and mechanical characteristics of lunarsoil simulant. In the respect of the morphology of terrain, developed a3-D Positioning andmeasurement system based on the electronic total station, measured the geometric parametersof the terrain in the infield, positioned the lunar craters and lunar rocks when prepared theinfield of rover. In the respect of the physical and mechanical characteristics of lunar soilsimulant, made the formulation processes to prepared different conditions of lunar soilsimulant, evaluated the result simplify by using SC-900soil penetrometer to measure theCone index of lunar soil simulant. Designed a multi-segment soil sampler apply to soft soil,which can get3soil samples of different depths, and the depths are at0to50mm,50to100mm,100to150mm, respectively. Comparing with the experiment that using cutting ringmethod to measure the bulk density of soft lunar soil, the multi-segment soil sampler canensure the original status of soil samples effectively, improve the accuracy, and improve the efficiency of sampling the soil in2to3times. The multi-segment soil sampler is suitable formeasuring the bulk density of the lunar soil simulant after serviced.A laser scanner that consisted of a laser sensor and a2-dimensional traversing frame wasdeveloped to measure the digit parameters of ruts in the soil bin which were produced by therigid wheel on loose soil. The maximum scanning area was650mm×400mm, measurementrange was0.05to65m and scanning resolution was0.1mm. A laser scanner with1-dimensional traversing frame which might be more appropriate for the measurements of rutdeformation in the infield of rover was also discussed. The experimental results showed thatthe scanners could obtain the sections and the3-D graphics of the surface of ruts by usingcontactless measuring method without disturbing the ruts.Developed a soil bin test system under light-load conditions according to the principle ofequivalent load, and the soil bin was used for researching the soil-wheel interactions betweenthe wire mesh wheel of rover and the lunar soil simulant. The soil bin could obtain the3-Dgraphics of ruts’ surface of wire mesh wheel with a laser scanner. According to the dualquadratic regression orthogonal composite design experiments of sinkage characters of wiremesh wheel under low slip rate, the sinkage regression equations about loads and speeds withthe lunar soil simulant under three different prepared conditions were presented as follows:(1)Soft condition, y=7.275-0.189x1+0.131x2-0.003x1x2+0.008x12;(2) Natural condition,y=4.507+0.189x1;(3) Compact condition, y=3.566+0.115x1. Regression equations showedthat: The sinkage of wire mesh wheel was decided by loads and speeds when lunar soilsimulant was soft; The sinkage of wire mesh wheel was linearly related to loads when lunarsoil simulant was natural or compact; Speeds influenced the sinkage of wire mesh wheelfuther with the lunar soil simulant changed from compact to soft. Results of the experimentsof sinkage characters of wire mesh wheel under different slip rate showed that: The sinkage increased with slip rate, the height of ruts decreased with the increase of slip rate, while lunarsoil simulant was under different prepared conditions; The sinkage and the height of ruts bothincreased, when lunar soil simulant changed from compact to soft. Experiments of rutssurface scan of wire mesh wheel showed that, the max sinkage of rut increased firstly andthen decreased, the max negative sinkage of rut increased, the shearing action of terrainincreased, the surface of rut was destroyed gradually, with the increase of slip rate. The resultsprovided basic experimental data for evaluating the sinkage of lunar rover and the physicaland mechanical characteristics of lunar soil simulant through ruts of wire mesh wheel.A INP file of lunar soil simulant was created in ABAQUS by meshing the stem, thendefined the physical and mechanical parameters in the INP file, translated the INP file to amodal neutral file by the ABAQUS interface for MSC.ADAMS. The flexible body of soil wascreated by importing the modal neutral file of lunar soil simulant into ADAMS, and therigid-flexible coupling simulation system of soil-wheel interactions between the rigid wheeland the lunar soil simulant was formed. Compared the simulation of the sink characteristics ofthe griddle net wheel with the soil bin experiments, that could provide methods to furtherresearch about the sinkage of lunar rover.