Study on the sinkage behaviour of legged robot's rigid foot in soft soil based on MM-ALE method

Abstract

In order to analyze the influence of rigid foot's geometry shape of legged robot on the sinking process in soft soil, MAT 147 material is used as the constitutive model of soil and the dynamic simulation of rigid foot's sinking process is carried out with Multi Material Arbitrary Lagrangian Eulerian(MM-ALE) method. The plate sinking test is simulated with MM-ALE method and the results are compared with the results from empirical formula proposed by Bekker. The results show that the maximum effective stress of soil concentrates at the bottom of the rigid foot near the edge and increases with the sinking of rigid foot, while the overall stress distributions are similar. The sinking depth has great influence on the range of the disturbed soil. The relationship between rigid foot's fillet radius and the stress distribution in the horizontal and vertical direction are studied and the soft soil flow trend are also analyzed. The results indicate that the bigger the fillet radius is, the more uniform the soil stress distribution at the bottom, but it has little influence on the side. Another finding is that the sinking depth has a positive correlation with fillet radius under the same pressure, while the maximum effective stress is opposite.