Tracking Control of Omni-Directional Vehicles Using Two Wheels Caster Type Odometer

This paper proposes a tracking control method for Omni-Directional Vehicles (ODVs) along desired trajectories using a new type of odometer, called a Two Wheels Caster Type (TWCT) odometer, specially designed for ODV dead-reckoning. Driving wheels of conventional ODVs slip easily. When an odometer is connected directly to a driving wheel shaft, such a slip causes large dead-reckoning error. The TWCT odometer we proposed is attached independently to the driving wheel of the ODV to avoid the influence of the slip. The TWCT odometer passively follows the omni-directional motion of the ODV. The current position and orientation of the ODV are estimated accurately by dead-reckoning from TWCT odometer measurement. The proposed control method uses the estimated current position and orientation that allow accurate tracking control of the ODV along a desired trajectory. Tracking control is improved by the TWCT odometer. Experimental results show effectiveness of the proposed control method using the TWCT odometer.