A 4WD Omnidirectional Wheelchair with Enhanced Step Climbing Capability

Masayoshi Wada

doi:10.20965/jrm.2008.p0846

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JRM Vol.20 No.6 pp. 846-853

doi: 10.20965/jrm.2008.p0846

(2008)

Paper:

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A 4WD Omnidirectional Wheelchair with Enhanced Step Climbing Capability

Masayoshi Wada

Department Human-Robotics, Faculty of Engineering Saitama Institute of Technology, 1690 Fusaiji, Fukaya, Saitama 369-0293, Japan

Received:

April 8, 2008

Accepted:

June 30, 2008

Published:

December 20, 2008

Keywords:

omnidirectional robot, four-wheel-drive, electric wheelchair, step climbing

Abstract

In developing an omnidirectional wheelchair tilted to climb single high steps, we enhanced standard step climbing by introducing a four-wheel drive (4WD). One pair of front and back wheels is connected by transmission belts to rotate in unison with a drive motor, i.e., synchrodrive transmission. To avoid wheel slippage as the mechanism turns, two omniwheels are installed in front and two regular tires in back, enabling the front wheels to slide freely sideways while the two back wheels continuously contact the ground. A third motor on the 4WD platform rotates the chair at the center of the mobile base around the vertical axis. The 4WD enhances step climbing over that of standard wheelchairs, but back wheels limit the step height climbed, meaning that front wheels climb higher steps than back wheels. We analyzed 4WD statics to clarify differences in front and back wheel step climbing, finding that drive torque caused the difference and that this influence depends on the wheelbase and vehicle weight distribution ratio of the front and back wheel axes. We varied the load distribution ratio among wheels to maximize back wheel step climbing. To do so, we developed chair tilting with a linear drive and an inclination sensor. The linear drive changes the chair's tilt angle for keeping the wheelchair statics and to vary positioning of the center of gravity (COG) to enable back wheels to climb steps more efficiently. To confirm the effectiveness of chair tilting in this scheme, we tested step climbing in experiments in which a prototype wheelchair carrying a user climbed a 90 mm step, but the back wheels failed when chair tilting was disabled.

Cite this article as:

M. Wada, “A 4WD Omnidirectional Wheelchair with Enhanced Step Climbing Capability,” J. Robot. Mechatron., Vol.20 No.6, pp. 846-853, 2008.

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References

[1] “Population Statistics Japan 2006,” the National Institute of Population and Social Security Research, Japan.
[2] “I-Bot wheelchair,” Independence Technology,
http://www.ibotnow.com/
[3] “Patrafour” Kanto Automobile Corp.,
http://www.kanto-aw.co.jp/jp/products/wheelchair/
[4] Jefferey Farnam, “Four-wheel Drive Wheel-chair with Compound Wheels,” US patent 4,823,900, 1989.
[5] http://mars.jpl.nasa.gov/MPF/mpf/rover.html
[6] Asama, et al, “Mutual Transportation of Cooperative Mobile Robots Using Forklift Mechanisms,” Proc. of the 1996 IEEE Int. Conf. on Robotics and Automation, pp. 1754-1759, 1996.
[7] H. Ikeda et al, “Step climbing and descending method by tandem wheelchairs and analysis of the influence of changes of the operator’s posture,” Journal of Society of Biomechanisms Japan, pp. 134-143, 2003.
[8] M. Wada and S. Mori, “Holonomic and Omnidirectional Vehicle with Conventional Tires,” Proc. of the 1996 IEEE Int. Conf. on Robotics and Automation (ICRA96), pp. 3671-3676, 1996.
[9] M. Wada, A. Takagi, and S.Mori, “Caster Drive Mechanisms for Holonomic and Omnidirectional Mobile Platforms with no Over Constraint,” Proc. of the 2000 IEEE Int. Conf. on Robotics and Automation (ICRA2000), pp. 1531-1538, 2000.
[10] M. Wada, “Holonomic and Omnidirectional Wheelchairs with synchronized 4WD Mechanism,” Proc. of the 2007 IEEE/RSJ Int. Conf. on Intelligent Robots and Systems (IROS2007), pp. 1196-1202, Dec 2007.
[11] M. Wada, “Omnidirectional and Holonomic Mobile Platform with Four-Wheel-Drive Mechanism for Wheelchairs,” Journal of Robotics and Mechatronics”, Vol.19, No.3, pp. 264-271, 2007.
[12] M. Wada, “4WD Omni-Directional Mobile Platform and its Application to Wheelchairs., Climbing and Walking Robots,” Houxiang Zhang (Ed.), Chapter 15, pp. 313-334, Advanced Robotic Systems Int., October, 2007.

This article is published under a Creative Commons Attribution-NoDerivatives 4.0 Internationa License.

[1] [1] “Population Statistics Japan 2006,” the National Institute of Population and Social Security Research, Japan.

[2] [2] “I-Bot wheelchair,” Independence Technology,
http://www.ibotnow.com/

[3] [3] “Patrafour” Kanto Automobile Corp.,
http://www.kanto-aw.co.jp/jp/products/wheelchair/

[4] [4] Jefferey Farnam, “Four-wheel Drive Wheel-chair with Compound Wheels,” US patent 4,823,900, 1989.

[5] [5] http://mars.jpl.nasa.gov/MPF/mpf/rover.html

[6] [6] Asama, et al, “Mutual Transportation of Cooperative Mobile Robots Using Forklift Mechanisms,” Proc. of the 1996 IEEE Int. Conf. on Robotics and Automation, pp. 1754-1759, 1996.

[7] [7] H. Ikeda et al, “Step climbing and descending method by tandem wheelchairs and analysis of the influence of changes of the operator’s posture,” Journal of Society of Biomechanisms Japan, pp. 134-143, 2003.

[8] [8] M. Wada and S. Mori, “Holonomic and Omnidirectional Vehicle with Conventional Tires,” Proc. of the 1996 IEEE Int. Conf. on Robotics and Automation (ICRA96), pp. 3671-3676, 1996.

[9] [9] M. Wada, A. Takagi, and S.Mori, “Caster Drive Mechanisms for Holonomic and Omnidirectional Mobile Platforms with no Over Constraint,” Proc. of the 2000 IEEE Int. Conf. on Robotics and Automation (ICRA2000), pp. 1531-1538, 2000.

[10] [10] M. Wada, “Holonomic and Omnidirectional Wheelchairs with synchronized 4WD Mechanism,” Proc. of the 2007 IEEE/RSJ Int. Conf. on Intelligent Robots and Systems (IROS2007), pp. 1196-1202, Dec 2007.

[11] [11] M. Wada, “Omnidirectional and Holonomic Mobile Platform with Four-Wheel-Drive Mechanism for Wheelchairs,” Journal of Robotics and Mechatronics”, Vol.19, No.3, pp. 264-271, 2007.

[12] [12] M. Wada, “4WD Omni-Directional Mobile Platform and its Application to Wheelchairs., Climbing and Walking Robots,” Houxiang Zhang (Ed.), Chapter 15, pp. 313-334, Advanced Robotic Systems Int., October, 2007.