Ultrasonic Sensors

This paper reviews the field of ultrasonic sensors for use in robotics with emphasis on sensors based on piezoelectric materials for use in air and in water. A detailed discussion is given of demands to sensors used for range and proximity measurements as well as of factors influencing the accuracy of these measurements. The structure of the ultrasonic field of a piston source is emphasized and the influence of sensor backing and load as well as bond lines on characteristic features of the ultrasonic field is discussed. The use of focused sources and aperture shading is evaluated and ultrasonic sensor calibration methods are presented. Finally, several ultrasonic sensor types for use in air and in water are presented including bimorph sensors and their characteristics.