Study on Mechanics Model of Leg Lift Retardation for Hexapod Robot in Clay Environment

doi:10.3969/j.issn.1004-132X.2025.09.011

Abstract

Abstract:

Hexapod robots often sinked and got stuck when walking in clay environment， which had a negative impact on the walking stability and energy consumption. The adhesion and shear resistance properties of clay were considered. A mechanics model of leg lifting block for a hexapod robot during foot sinking was established. The correlation between foot subsidence and leg lifting resistance was revealed， and the foot-ground mechanics experimental platform was designed and constructed. Based on this platform， foot-ground mechanics experiments were conducted on hexapod robots under three gaits. Data on sinking and blocking forces were obtained. The accuracy of the mechanics model was verified by comparing with the calculated results of theoretical model. Finally， EDEM software was used to simulate the clay environment and perform foot-ground contact simulations. The variation law of the internal mechanics behavior of clay was revealed. The comparisons of the results from simulation， mechanics model prediction and experiments show that the data change trends are basically the same.

Key words: hexapod robot, clay environment, foot-ground contact mechanics model, foot-ground mechanics experiment

摘要：

六足机器人在黏土环境下行走时常发生沉陷且脱困受阻，对其行走稳定性及能耗等方面均产生了负面影响。考虑黏土的黏附特性及抗剪特性，建立了六足机器人在发生沉陷时的抬腿阻滞力学模型，揭示了足端沉陷量与抬腿阻滞力之间的相关性。设计并搭建了足地力学实验平台，基于该平台进行了六足机器人在3种步态下的足地力学实验，获得沉陷量与阻滞力数据，并与理论模型计算结果对比，验证了力学模型的准确性。采用EDEM软件模拟黏土环境，进行足地接触仿真，揭示了黏土内部力学行为变化规律。对比仿真结果、力学模型预测结果和实验结果发现数据变化趋势基本一致。

关键词: 六足机器人, 黏土环境, 足地接触力学模型, 足地力学实验

CLC Number:

TP242

Haoxi ZHANG, Jie JIANG, Gang JIANG, Yue LI, Xing'an HAO. Study on Mechanics Model of Leg Lift Retardation for Hexapod Robot in Clay Environment[J]. China Mechanical Engineering, 2025, 36(9): 1996-2002.

张颢曦, 姜杰, 蒋刚, 李月, 郝兴安. 黏土环境下六足机器人抬腿阻滞力学模型研究[J]. 中国机械工程, 2025, 36(9): 1996-2002.

Figures/Tables 10

Fig.1 Model of leg lift block

Fig.2 Foot-ground mechanics experiment platform

Fig.3 Vertical actuator of experimental platform

Tab.1 Comparison of parameters of target soil and simulated soil

参数	黏聚力/kPa	内摩擦角/（°）	容重/（kN·m^-3）
目标黏土	5	16.4	18.6
模拟黏土	5	15.7	16.2
粉土^［14］	15	25	17.3
砂土^［15］	0	36	15.1

Fig.4 The relationship between resistance and time

Fig.5 The relationship between subsidence and settlement（errors of experiments and theories）

Tab.2 Contact model characteristics and applicable scenarios

接触模型	黏性	压缩性	适用场景
Hertz-Mindlin	无	无	常规颗粒接触
Edinburgh Elasto-Plastic Adhesion	有	有	黏弹塑性颗粒接触
Hysteretic Spring	无	有	受压后塑性形变颗粒接触
Hertz-Mindlin with JKR	有	无	粉体或湿颗粒接触
Bonding	有	有	破碎颗粒接触
Electrostatics	有	无	静电颗粒接触

Tab.3 Soil particle parameter

参数	数值
颗粒粒径/mm	2
颗粒密度/（ $k g$ ·m³）	2600
泊松比	0.25
剪切模量/Pa	$1 × 107$
恢复系数	0.75
静摩擦因数	1.16
滚动摩擦因数	0.29
表面能/（ $J$ ·m^-2）	0.6

Tab.3 Soil particle parameter

参数	数值
颗粒粒径/mm	2
颗粒密度/（ $k g$ ·m³）	2600
泊松比	0.25
剪切模量/Pa	$1 × 107$
恢复系数	0.75
静摩擦因数	1.16
滚动摩擦因数	0.29
表面能/（ $J$ ·m^-2）	0.6

Fig.6 Soil particle stress vector distribution

Fig.7 The relationship between subsidence and settlement（errors of simulations and theories）

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