Stress and Sinking Property Analysis of Legged Robot Foot with Toe Structure in Soft Soil

Sinking problem limits the walking performer of legged robot working in soft soil. The shape of robot's foot is very important to its sinking property. In order to study the influence of foot geometric shape on its sinking property in soil, Multi-Material Arbitrary Langrange-Euler (MM-ALE) method are used in the numerical simulation of sinking process of robot foot with different shape in soil. The results of soil's flow trend and stress distribution, and foot sinkage are analyzed, which show that multi-toe structure influences the direction of soil's flow and the direction of principal stress, and helps to form a low velocity area at the corner of multi-toe foot, and leads to the decreasing of the sinkage of robot foot. The rib and groove structures are added to the cross-shaped of foot, and the results show that the groove changes the principal stress direction of soil under robot foot, which influences soil's flowing tread, and make soil compact locally, so sinkage is decreased. This research provides a valuable reference for the shape design of legged robot foot walking in soil.