Exploring Tractive Performance of Planetary Rover's Rigid Wheels on Mixed Terrain

Guanglong Zhai,Tieqiu Huang

doi:10.1051/jnwpu/20203861240

Guanglong Zhai, Tieqiu Huang

Open Access

https://doi.org/10.1051/jnwpu/20203861240

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Abstract

Based on insufficient studies of the tractive performance of a planetary rover's rigid wheels in soft soil and hard mixed soil terrains, a method for studying the tractive performance is presented. The Wong-Reece' interaction model was used as the dynamic model for wheel-soil contact. The sinkage model and the drawbar pull force model were modified and then verified with experimental results. Based on the Hertz contact theory, a nonlinear friction spring damping model was adopted as the wheel-bedrock contact model. An additional terrain hardness array was introduced for setting and recognizing the mixed terrain with ground mechanics parameters. With the platform for co-simulating the navigation and dynamics of a planetary rover, the simulation program was developed to dynamically simulate the whole planetary rover with two wheel-ground contact models. Taking the Mars rover as an example, its whole model was established with the MSC.Adams software. The dynamic simulation of the Mars rover on the soft terrain and mixed terrain was carried out respectively. The simulation results show that the Mars rover's velocity fluctuates greatly on the mixed terrain, and that the Mars rover gains greater drawbar pull force when traveling on the mixed terrain than on the only soil terrain.

Highlights

使土壤发生沉陷,在地面力学中,轮下土壤的应力特性分为承压特性和剪切特性,承压特性的模型采用 Wong⁃Reece 正应力模型[5] , 剪切特性的模型采用 Janosi 剪切模型[6] 。在软土地形中,车轮受力如图 1 所示。其中: W,T 和 FDP 分别为车轮所受载荷、驱动力矩和挂钩牵引力;r 为车轮半径;Z1,Z2 分别为车轮的最大沉陷和土壤回弹高度;θ1,θ2 和 θm 分别为进入角、离去角和最大应力角;ω 和 v 为车轮角速度和前进速度;σ 为正应力;τ 为剪应力。
The Wong⁃Reece′ inter⁃ action model was used as the dynamic model for wheel⁃soil contact
Based on the Hertz contact theory, a nonlinear friction spring damping model was adopted as the wheel⁃bedrock contact model

Summary

Introduction

使土壤发生沉陷,在地面力学中,轮下土壤的应力特性分为承压特性和剪切特性,承压特性的模型采用 Wong⁃Reece 正应力模型[5] , 剪切特性的模型采用 Janosi 剪切模型[6] 。在软土地形中,车轮受力如图 1 所示。其中: W,T 和 FDP 分别为车轮所受载荷、驱动力矩和挂钩牵引力;r 为车轮半径;Z1,Z2 分别为车轮的最大沉陷和土壤回弹高度;θ1,θ2 和 θm 分别为进入角、离去角和最大应力角;ω 和 v 为车轮角速度和前进速度;σ 为正应力;τ 为剪应力。根据 Wong⁃Reece 正应力模型,承压模型中正应力 σ( θ) 分布如(1) 式所示[5] 单轮实验结果与仿真结果对比如图 3 所示。从图 3a)中可知:未修正的沉陷模型随滑转率变化较小,这是因为模型中未考虑车轮由于滑转所导致的车轮下陷,滑转率越大,滑转沉陷量越大,修正后的沉陷量模型与实验结果趋于一致;从图 3b) 中可知: 未修正的挂钩牵引力模型在滑转率处于 0 ~ 0.2 之间时与实验结果基本符合,当滑转率大于 0.2 时,未修正的挂钩牵引力模型与实验结果相差较大,出现偏差是因为车轮在滑转率较大时,车轮滑转会带来附加的阻力,修正后的挂钩牵引力的变化趋势与实验结果基本一致;从图 3c) 可知,Wong⁃Reece 模型驱动阻力矩与实验结果趋势上一致。航天器环境工程, 2003, 20(2) : 5⁃14 XIAO Fugen, PANG Hewei.

Results

Conclusion