A Mecanum wheel model based on orthotropic friction with experimental validation

Abstract

Mecanum wheels are commonly used in mobile robotics applications as they enable a platform with three or more individually controlled wheels to move in arbitrary directions without turning. However, compared to the well-studied models for pneumatic and railroad wheels, modeling of Mecanum wheels remains mostly unexplored. In this research a novel, efficient Mecanum wheel model, based on orthotropic friction to model roller-ground contact, is presented together with experimental data. The equations are derived and the Mecanum wheel model is implemented in an open source multibody simulation code and shown to run faster than real-time with time steps in the order of milliseconds, enabling the model to be utilized for control tasks. Extensive experiments are performed with a real robot and statistical evaluation is presented. Both different robot velocities and changes in the center of mass, representing different payloads of the robot, are showcased. The simulation model captures the deviations from the idealized kinematics realistically and can reproduce the measurements.