The objective of the research is to increase ground passing ability and ecological compatibility of legged locomotion mover (LLM) at water-saturated grounds. For the study a method of mathematical simulation of mechanics of foot contact with ground was used by means of the package of finite-element simulation software ANSYS (ANSYS Inc.). The process of interaction of LLM with ground can be divided on the phase of foot change and the phase of traction power. For dynamics of foot change as a calculation scheme was assumed a scheme for two-legged locomotion machine with vertical translational body movement. The simulation has shown that during leg change there are vibrations of legs in the ground. Wherein support reactions can significantly (in 2 times and more) exceed the static ones. However, vibrations at water-saturated tough grounds provided by leg change occupy a small part of cycle (about 5 %). Therefore, an interaction of the foot with ground in support phase can be considered as quasi-static. The impact of foot shape as well as average pressure on the ground on its stress state was found out. The least impact on soil at the same equal conditions was made by ski-shaped foot. It was proved that for ski-shaped foot the impact rate on soil according to the standard (GOST 26955–86) is required an average pressure of the foot on the ground about 0.08 MPa. At water-saturated grounds with low elastic properties the pressure of the foot on the ground should be decreased to 0.03–0.04 MPa. Otherwise, inadmissibly high ground deformations occur. The results obtained can be used either in design of elementary legged locomotion machines, for example for new soil-protected technologies in irrigated agriculture, or for complex robotics systems intended for operation in extreme conditions.
Keywords: legged locomotion machine, interaction of mover and ground, soft ground, dynamic simulation, stress state of the ground.
