An omnidirectional wheel based on Reuleaux-triangles

This paper discusses the mechanical design and simulation of a novel omnidirectional wheel based on Reuleaux-triangles. The main feature of our omniwheel is that the point of contact of the wheel with the floor is always at the same distance from the center of rotation. This produces smooth translational movement on a flat surface, even when the profile of the complete wheel assembly has gaps between the passive rollers. The grip of the wheel with the floor is also improved. The design described in this paper is ideal for hard surfaces, and can be scaled to fit small or large vehicles. 1 Omnidirectional wheels Omnidirectional wheels have been used in robotics, in industry, and in logistics for many years. The main source for omnidirectional wheels are companies which produce them for omnidirectional transportation tables, such as those used by postal or package handling companies. Omnidirectional wheels have been used to build omnidirectional robots, specially in the RoboCup setting. An omnidirectional robot can drive along a straight line from point to point, while rotating along this line in order to arrive with the correct orientation. Omnidrectional wheels have also been used for wheel chairs, for service vehicles in airports, and many other applications. The first omnidirectional wheels were developed by the Swedish inventor Bengt Ilon around 1973 [1]. Fig. 1 shows the design of the wheel and a fork lift built using them. The profile of the wheel is more or less round. The wheel is omnidirectional but transversal forces produce excessive friction in the axes of the small rollers. A clever alternative are “Killough rollers” [2], which are usually built using two truncated spheres. Such rollers were used by the Cornell RoboCup team in 2000, and were still in use until 2004 in RoboCup competitions. Many RoboCup teams use now self-built wheels or a variation of commercial wheels built for transport platforms, such as those shown in Fig. 2. Geometrically, such