Autonomous docking of miniature spherical robots with an external 2D laser rangefinder

This paper presents an autonomous docking strategy for miniature spherical rolling robots. Due to their small physical size, these robots do not have onboard depth sensing capabilities, and have difficulty docking autonomously to a charging station. This docking/charging station has been augmented with a 2D LiDAR, which is used to scan the immediate area to detect the position of the robot; a waypoint is then calculated and transmitted via a low power wireless network. This forms a closed-loop position control system, eliminating any accumulated position errors due to odometry or heading drift. This novel system is able to detect a spherical robot, which is devoid of any distinct features, and more importantly does not require any depth or vision sensors to be installed on the miniature robot for the docking procedure. The described strategy is implemented and practical test results are illustrated.