A fast and accurate sonar-ring sensor for a mobile robot

A sonar-ring is one of the most popular sensors for indoor mobile robots, because it is simple and gives omni-directional distance information directly. However, it is difficult to measure the accurate direction of reflecting points by a conventional sonar-ring sensor. Further more, conventional sonar-ring sensors are slow to get full 360 degrees information due to sequential driving of transducers for avoiding interference. We propose a new sonar-ring sensor system for a mobile robot which can measure the accurate bearing angles of reflecting objects in a single measurement. The proposed system employs measurement by using differences of time-of-flight and by simultaneous transmit/receive of all directions, and consequently achieve fast measurement. We implemented a prototype of the proposed sonar-ring on a mobile robot. Experimental data show the effectiveness of the proposed system