Two wheels caster type odometer for omni-directional vehicles

This paper proposes a new type of two wheels caster type odometer to estimate the current position and orientation of omni-directional vehicles. The proposed odometer is composed of two passive wheels and one passive rotational axis. The two wheels rotate independently, and the rotational axis changes the odometer´s orientation as the omni-directional vehicle moves. Three rotary encoders using a gear train measure angular velocities of the two wheels and rotational axis. A mechanism of the gear train is proposed to prevent the encoder from being entangled with it. Using measured values of the three encoders, the current velocity vector of an omni-directional vehicle is calculated by kinematics of the odometer. Using the velocity vector, the current position and orientation of the omni-directional vehicle are estimated by dead reckoning. Results of localization experiments by the developed odometer are shown.