Path Tracking Control Method of a Modular Omnidirectional Vehicle.

Abstract

This paper proposes a control method for moving a non-holonomic omnidirectional vehicle along a reference path. We modularize wheel units assembled in the vehicle to easily tailor the vehicle to individual transfer applications. A path-tracking control system 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 motion of the vehicle based on the Ackerman geomery to track its reference path, while each wheel-module controller controls wheels to produce the desired motion of the vehicle. To reduce wheel slip caused by control errors in wheel modules, we constitute two types of wheel modules : active wheel modules and passive wheel modules. The active wheel modules produce the desired vehicle motion, and the passive wheel modules correct their own velocities to mimic caster behavior. Simulation and experiment confirmed the effectiveness of the proposed control.