Fast-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.