Design of cluster geometries for clusterwheel IP robots: Obstacle size and controllability

In this paper we discuss issues related to the design of clusterwheel inverted pendulum balancing machines, with a particular focus on the choice of the number of wheels in the cluster. This class of vehicles holds the promise of incorporating the inherent compliance of a two-wheeled balancing vehicle, the stability of a four-wheeled vehicle when desired, and the capability of legs to overcome obstacles such as stairs and indoor terrain. In order to arrive at a design compromise that can retain the advantages of each mode while minimizing disadvantages, we examine the dynamics and control of various cluster geometries and give analytical arguments in support of a three wheel cluster design while verifying our hypothesis using simulations of various cluster architectures. We then present the design and the construction of “Charlie,” a prototype clusterwheel vehicle, and demonstrate basic stable obstacle traversal.