Rapid and accurate inter-robot position determination in robot teams

We describe a rapid and accurate method to measure robot-to-robot separations and headings. The method, which uses narrow bandwidth signals that are well suited for ultrasonic transducers and for dispersive acoustic environments, detects the difference in phase delay of an optical and an ultrasonic signal. A prototype system based on microcontrollers for signal generation and phase delay measurement determined the location of another robot with sub-centimeter accuracy over a 2.5 m range with a 53 ms measurement time. We also describe simple modifications that can be made to increase the range without loss of accuracy and to coordinate measurements among many robots.