Fast and Accurate Simulation of Mecanum Wheels with Passive Rollers Emulated by Fixed Joints and Anisotropic Friction*

Simulating mecanum wheels, ubiquitous in robotics and industry, is a critical tool for advancing research and development on robots equipped with these wheels. This study proposes a fast and accurate simulation model for mecanum wheels, where passive rotating rollers attached to the wheel's outer circumference are represented with fixed joints and anisotropic friction links. The simulation is fast because the constraints on the rotation axis of the roller do not need to be explicitly considered in the physics calculation. The barrel shape of the roller is approximated using multiple spherical links placed along the axis of the roller. As this approach replicates the shape with fewer polygons, simulation accuracy is maintained, and collision detection during the physics calculation can be accelerated. Comparison experiments with conventional models and an actual vehicle confirm that a simulation accuracy close to that of the actual vehicle can be achieved at a calculation speed more than three times those of conventional models. The proposed simulation model may aid in the development of transportation vehicles for factory applications, and it may replace labor-intensive experiments on swarm vehicles to expedite research and development therein.