A 4WD omnidirectional wheelchair with a chair tilting system

This paper presents a development of a 4WD omnidirectional wheelchair with a chair tilting system for climbing single high step. For enhancing the step climb capability of standard wheelchairs, a Four-wheel-drive(4WD) mechanism is introduced. The mobile platform equips four wheels. A pair of front-rear wheels which mounted on the same side of the mechanism, are interconnected by belt transmissions to rotate in unison with a drive motor, i.e. a synchro-drive transmission. To avoid slippage of wheels on the ground, two omni-wheels are installed in front while two normal tires are equipped in rear, which configuration enables the free sliding of the front side of the mobile mechanism while the rear two wheels are guaranteed confirmed contacting to the ground at all times. Additionally, to rotate a chair at the center of the mobile base about vertical axis, the third motor is installed on the 4WD platform.