<title>Experimental characterization of Polaroid ultrasonic sensors in single and phased array configuration</title>

Abstract

Many mobile robots use Polaroid ultrasonic sensors for obstacle avoidance. This paper describes the experimental characterization of these sensors using a unique, fully automated testbed system. Using this testbed, we gathered large data sets of 5,000-16,000 data points in every experiment for characterization purposes; in a repeatable fashion and without human supervision. In the experimental characterization reported in this paper we focused on a comparison of the beamwidth of a single sonar with that of a dual sonar phased array. For the single sonar we found that flat walls trigger echo signals up to an angle of +/- 42 degree(s), which is well beyond the traditional assumed beamwidth of +/- 15 degree(s). We determined that these echoes result from the secondary and tertiary lobe of the well known multi-lobed propagation patterns of Polaroid ultrasonic sensors. In contrast, with the dual sonar phased array echo signals were triggered only up to beamwidths of 4-6 degree(s). The results in this paper were obtained for two test targets: a specular surface and a cylindrical object.