An omnidirectional mobile robot: Concept and analysis

This paper presents a novel omnidirectional wheel mechanism, referred to as MY wheel-II, based on a sliced ball structure. The wheel consists of two balls of equal diameter on a common shaft and both balls are sliced into four spherical crowns. The two sets of spherical crowns are mounted at 45° from each other to produce a combined circular profile. Compared with previous MY wheel mechanism, this improved wheel mechanism not only is more insensitive to fragments and irregularities on the floor but also has a higher payload capacity. A kinematic model of a three-wheeled prototype platform is also derived, and the problem of wheel angular velocity fluctuations caused by the specific mechanical structure is studied. The optimal scale factor (OSF) leading to a minimum of trajectory error is adopted to solve this problem. The factors influencing the OSF are investigated through simulation. In addition, the methods used for determining the OSF are discussed briefly.