A mobile robot for sensing and decoding a surface coding pattern on a surface includes a housing, A platform is in the housing. An on-board controller is mounted on the platform and configured for wireless communication with a host computer system. A differential drive system is mounted on the platform and connected to the controller so that the controller can steer the platform relative to the surface. An image sensor is mounted on the platform, arranged to sense the surface coding pattern and connected to the controller to communicate data representing the surface coding pattern to the host computer via the controller.