Direction-sensitive ultrasonic distance sensor using multimode stimulation of a single transducer

A novel ultrasonic sensor is presented which has the ability to determine the angle of incidence of sound waves by evaluating simultaneously different vibration modes of a single transducer. Since signals from the main lobe and sidelobes are discernible, side reflections can be identified and suppressed. Combining angle and distance measurement allows a detailed characterization of object scenes. The signal evaluation is performed by an adaptive algorithm incorporating Wiener filtering to improve the angular and axial resolution. The principle of the sensor is described and results for different object scenes are presented. Investigations on level measurements in silos proved the practical applicability of the method.