We propose here an ultrasonic range sensor based docking system for a mobile robots. Our method makes the robot to dock to a target at a specific location and orientation. Two active IR beacons are placed in such a way that the location of the docking target lies on the Voronoi Partition of the beacons. These beacons transmit infrared signal in all directions. The robot detects the beacons and successfully reaches the docking target with the required orientation.