Modelling and Simulation of Mobile Six-Legged Robot with Leg-Soil Contact

Abstract :

A nontrivial difference between wheel-soil contact and leg-soil contact is the normal stress at the contact area. The normal stress of wheel-soil contact can be easily expressed by a static function because the direction of load force is not changed, whereas the normal stress of leg-soil contact is dynamically changed by leg behaviours. In this paper, a footsoil contact model for an extraterrestrial six-legged robot simulation is presented. In this contact model, the Bekker mobility model is integrated into the penalty-based approach. The normal and shear stress of dynamical foot-soil contact behaviours can be calculated by using this contact model. A modelling and simulation of the extraterrestrial sixlegged robot system with the foot-soil contact model is implemented in a high-fidelity co-simulation framework based on Adams/View and Matlab/Simulink. The six-legged robot kinematics is modelled on Adams/View, the control algorithms are modelled on Matlab/Simulink, and the connections between robot kinematics and control algorithms are defined. Contact functions written by C++ are added to the co-simulation framework in order to implement the proposed model of the foot-soil contact dynamics. In this implementation, the normal and shear stresses from foot-soil contacts with walking locomotion behaviours are simulated.