Abstract
Abstract
Accurate prediction of locomotion on deformable terrain requires models that resolve the mutual coupling between robot motion and the evolving granular support, rather than assuming a prescribed contact condition. This study presents a coupled discrete-element–multibody-dynamics framework for a twelve-legged radial-skeleton spherical robot moving on granular terrain. The model represents the terrain with spherical particles governed by the discrete element method and the robot as a constrained multibody system with triangulated foot surfaces, and it introduces a particle–facet contact formulation that includes normal, tangential, rolling, and torsional resistance while transferring contact forces and moments consistently to the rigid bodies. Combined with grid-based contact search, synchronized explicit integration, and graphics-processing-unit-based parallel computation, the framework enables efficient simulation of intermittent foot contact, load redistribution, local penetration, and terrain disturbance during rolling locomotion. Verification against classical discrete-element and multibody-dynamics benchmark cases, together with a full locomotion simulation, shows that the proposed method captures both the robot trajectory and the granular support evolution that governs its motion.