Influences of lug motion on lug-soil reaction forces in sandy soil

Wheeled mobile robots working on sandy soil (e.g. planetary surface, desert, etc.) are commonly equipped with lugs (i.e. grousers) on wheels to improve travelling performance. It has been verified that presence of these lugs significantly affects on the traction performance of the locomotion mechanisms on soft terrains. However, the influences of movable lugs on traction performance are unclear, since the motion behavior of the conventional fixed lugs are interfered by wheel´s motion. To quantitatively confirm the influences of lug´s motion, we measured the soil reaction forces acting on a single actively actuated lug without wheel in various motion scenarios. Based on experimental results, we mathematically established relationships between the lug-soil interaction forces and parameters of lug´s motion, such as inclination angle, moving velocity, and sinkage length of the lug.