We postulate that multi-wheel statically-stable mobile robots for operation in human environments are an evolutionary dead end. Robots of this class tall enough to interact meaningfully with people must have low centers of gravity, overly wide bases of support, and very low accelerations to avoid tipping over. Accordingly, we are developing an inverse of this type of mobile robot that is the height, width, and weight of a person, having a high center of gravity, that balances dynamically on a

more »

... ngle spherical wheel. Unlike balancing 2-wheel platforms which must turn before driving in some direction, the single-wheel robot can move directly in any direction. We present the overall design, actuator mechanism based on an inverse mouse-ball drive, control system, and initial results including dynamic balancing, station keeping, and point-to-point motion.