Abstract: Motion system with Mecanum wheels can move in omni-direction on flat floor without needing steering wheels. When it moves on uneven floor, because of the variety of touch state and the coupling between wheels and uneven floor, the system has an additional attitude angle motion besides the plane motion, so the system motion characteristics cannot be described by three-dimensional kinematics model. In order to study the kinematics model which can be applied on uneven floor, the touch state is cataloged and the system motion characteristics are analyzed, then six-dimensional kinematics model is presented according to vector and coordinate transform method and the necessary motion conditions of the Mecanum wheel system are elucidated. It is proved that the six-dimensional kinematics model is suitable not only for plane floor but also for uneven floor, so it is the general kinematics model.

Key words: General kinematics model, Mecanum wheel, Omni-directional motion, Uneven floor