A Fast and Accurate Reflecting Points Measurable Sonar-ring System

A sonar-ring is one of the most popular sensor for indoor mobile robots, because it is simple and gives omnidirectional distance information directly. However, it is difficult to measure accurate bearing of reflecting points by a conventional sonar-ring sensor. And also, it is slow to get omni-directional information due to sequential driving of transducers for avoiding interference of ultrasound. In this paper, we propose a new sonar-ring sensor system for a mobile robot which can measure the accurate bearing angles of reflecting objects. The proposed system employs both simultaneous transmission/receive of all directions and accurate bearing angle measurement using differences of time-of-flight, and consequently archived fast and accurate measurement. We implemented a prototype of the proposed sonar-ring on a mobile robot, and experimental data show the effectiveness of the proposed method.