Measurement of Angular Position of a Mobile Robot Using Ultrasonic Sensors

Ultrasonic sensors are commonly used in robotics for range measurement in obstacle detection and avoidance systems. They have also been used for localization by map matching techniques. This paper presents a novel use of ultrasonic sensors for the measurement of angular position of a mobile robot relative to a known ultrasonic source. The method is based on measurement of the phase difference of an ultrasonic wave by two receivers. The receivers are positioned on-board a mobile robot, and the phase difference therefore represents the angular position of the robot. The paper presents an experimental set up, in which the technique was tested. Experimental results show the accuracy and operational limitations of the technique.