Path tracking control of a non-holonomic modular omnidirectional vehicle

This paper proposes a method for controlling a non-holonomic omnidirectional vehicle. We modularize wheel units assembled in the vehicle to easily tailor the vehicle to individual transfer applications. A controller consisting of deck-module and wheel-module controllers is designed to coordinate wheel modules and to ensure correct vehicle motion. The deck-module controller decides the desired vehicle motion based on the Ackerman geometry to track the reference path of the vehicle, while each wheel-module controller controlling the wheel motion to produce the desired vehicle motion defined by the deck-module controller. To reduce wheel slip caused by control errors in wheel modules, we design two types of wheel modules: active and passive. The active wheel module produces the desired vehicle motion, and the passive wheel module corrects its own velocity to mimic caster behavior. Simulation and experiments confirmed the effectiveness of the proposed path tracking control