Active Hearing For External Imaging Based On An Ultrasonic Transducer Array

A bstract-Ultrasonic ranging systems are widely used for mobile robot navigation; despite their simplicity and low cost, such systems suffer from a few shortcomings, mainly due to some unfavourable characteristics of sound propagation in air. Methodologies for emending the typical errors arising in the processing of sparse wide-angle sonar data are needed for obtaining meaningful maps of the environment: we are investigating a transducer array configuration that extracts features such as walls or edges in a specular 2D robot world by processing time-of-flights. Accurate target localization data, both in range and azimuth, are provided as well. Purposeful active sensing techniques are introduced, aiming at gathering sensorial data in less d ifficult operating conditions: given the azimuth estimates, a tracking procedure is issued that may significantly improve the Signal-to-Noise ratio at the receiver site by pointing the transducers directly toward the target. The proposed array configuration can efficiently map objects in the environment up to several meters: experimental results closely agree with the predictions provided by theoretical models of sound propagation and noise phenomena.