Volume 21 Issue 05/06 - Publication Date: 1 May 2002
Nonholonomy on Purpose
Mechanism, Control and Design Methodology of the Nonholonomic Quasi-Omnidirectional Vehicle 'ODV9'
Yoshikazu Mori Graduate School of Engineering Tokyo Metropolitan University 1-1 Minami-Osawa, Hachioji Tokyo 192-0397, Japan , Eiji Nakano and Takayuki Takahashi Graduate School of Information Sciences Tohoku University, 01 Aoba, Aramaki-aza, Aoba-ku Sendai 980-8579, Japan
The purpose of this paper is to discuss the design of ODV9, a nonholonomic quasi-omnidirectional vehicle to be used as a general platform for mobile robots. Omnidirectional mobility is a desirable property for such a platform because indoor mobile robots are often requested to move in a narrow space. ODV9 has four wheel modules, and each module incorporates one motor, one steering brake, and one conventional wheel equipped with a rubber tire. The use of caster wheels means that ODV9 can be operated with just two motors. Compared with other omnidirectional vehicles, the advantages of ODV9 are not limited to the simplicity of its mechanism. Benefiting from being able to use pneumatic tires, ODV9 is capable of moving on somewhat bumpy road surfaces. The disadvantage of ODV9 is inferiority in its maneuverability. The quasi-omnidirectionality means that an arbitrary x, y and yaw motion cannot be achieved. The disadvantage is, however, compensated by proper use of many possible running modes according to the situation. Experimental results and simulations verify the effectiveness of the design. The ability of ODV9 to get over a step and change its width is also discussed.
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