基于应力分布的月球车轮地相互作用地面力学模型

Terramechanics Model for Wheel-terrain Interaction of Lunar Rover Based on Stress Distribution

轮地相互作用地面力学在月球车的设计、性能评价、控制和仿真等方面具有重要作用,是目前基于动力学进行月球车相关研究的瓶颈。基于此,利用针对月球车开发的车轮—土壤相互作用测试系统进行试验,结合试验数据对传统车辆轮地相互作用正应力和切应力分布模型进行修正,并分析月球车轮刺高度对应力分布的影响,从而提出随滑转率变化改变沉陷指数的经验公式,以反映土壤侧向流动等引起的滑转沉陷。对应力分布公式积分得到集中力/力矩计算模型,并结合试验数据进行验证。在载荷为80N,滑转率从0.05增加到0.6时,模型对于车轮垂直载荷、挂钩牵引力和驱动力矩的计算值与试验数据相比,相对误差不超过10%。模型能够反映滑转沉陷和轮刺效应,可以有效地用于月球车轮地相互作用力学的计算。

Terramechanics for wheel-terrain interaction of lunar exploring rover, which is the bottleneck of dynamics-based research at present, can play an important role in mechanical design, performance evaluation, control, simulation, etc. Experiments are done by using the wheel-terrain interaction testing system developed for lunar rover. The conventional normal and shear stress distribution models are improved according to the experimental data. And the effect caused by the wheel lugs is also analyzed. To retie ct the slip-sinkage caused by lateral flow of deformable soil, the concept that the sinkage exponent should vary according to the slip ratio is proposed and an empirical formula is given. Mathematic model for calculating concentrated force/torque is deduce d by integrating the distributed stresses, which is verified by experimental data. With a load of 80 N, while the slip ratio increases from 0.05 to 0.6, the relative error of calculated value and experimental data for normal load, drawbar pull and driving torque is less than 10%. The model can reflect slip-sinkage and the effect of wheel lugs, and can be used effectively for the calculation of wheel-terrain interaction mechanics.