East-Bearing Measurement With A Single Ultrasonic Transducer

In conventional ultrasonic sensing, accurate ultrasonic target-bearing measurement is often regarded as difficult, due to the wide-beam angle of ultrasonic transducers. However; the accurate measurement of distances and angles is useful for many robot tasks such as obstacle avoidance and wall following. In this paper; we propose a method for extracting bearing information by using a single transducer in ultrasonic pulse-echo sensing, which basically exploits the dependency of the echo spectrum on bearing angle. The method employs a simple approach using a zero-crossing time interval of the reflected echo, and consequently is a fast measurement technique This paper also presents experimental results on a real mobile robot and illustrates the usefulness of the ultrasonic bearing-measurement approach.