Towards a Real-Time Capable Realistic Soil Contact Model Using a Particle System

Abstract :

Soil contact dynamics is a key figure in simulations of multi-body dynamics such as ground vehicles and walking robots. Since most 3-dimensional rigid body simulators provide only simple contact models using stiffness and friction properties, they are unsuitable for modeling complex soil contacts with legs and blades. Some finite element approaches have been introduced to model complex soil dynamics in the last decade. However, it is still difficult for finite element approaches to provide real-time capability. Meanwhile, in many previous researches of planetary exploration and extraterrestrial systems, analytical approaches such as Bekker’s mobility model [1] and Terzaghi’s soil deformation model [2] have been widely used to simulate soil contact behaviors of wheel vehicle systems and excavation systems. However, the main drawbacks of such analytical models are that 1) a lot of soil parameters such as angle of internal friction, soil stiffness, soil cohesion, shear deformation modulus, soil density, etc., are necessary to describe soil contact models, 2) the accuracy of measured soil parameters cannot be guaranteed in all test environments because the parameters can change depending on the states of temperature or humidity, 3) mathematical formulas of contact models strongly depend on the body-shape of contact objects, and 4) it is difficult to describe a contact model for a heterogeneous soil because of the complex soil parameters.