Analysis of the Effect of Soft Soil’s Parameters Change on Planetary Vehicles’ Dynamic Response

摘要

The mobility of a planetary vehicle has numerous constraintsimposed by the types of terrain. Navigation isdifficult through uneven and rocky terrain, and becomesworse due to abrupt changes of ground level which maycause a fall to a lower ground level. This article examinesthe effect of the soil’s parameters change due to repetitivefalls on the vehicle’s dynamic behavior. After eachfree fall of the vehicle there is a collision of the vehicle’swheel with the ground. If the ground is made up of softsoil there is an increase in the soil compactness after eachcollision. The increase in the soil compactness causes achange in the soil parameters. These changes modify thealgorithm’s parameters of the vehicle’s dynamic model.The dynamic model is a quarter vehicle model with singlerigid wheel which falls on soft soil. Simplified formsof the Pressure-Sinkage models of Bekker and Reece forthe sinkage of a rigid body into soft soil are incorporatedin the numerical solution of the governing equations ofmotion. The dynamic interaction of a rigid wheel and softsoil has three stages: sinkage stage, wheel dwell stage,and wheel pullout from soil stage. By comparing thesimulations results when the soil’s parameters are keptconstant and when their changes are incorporated in thedynamic model showed that the difference in the dynamicresponse are not significant and can be neglected. Thereis a gradual change in the dynamic mechanical quantitieswhen the soil’s parameters are kept constant, while thechanges in the dynamic mechanical quantities betweenthe second fall and the successive falls are small.