A low sample rate 3D sonar sensor for mobile robots

This paper describes an ultrasonic sensor which uses the times of flight from three Polaroid ultrasonic transducers arranged in an equilateral triangle to identify and localise planes, 2D and 3D corners. The sensor employs a maximum likelihood estimator and a data acquisition system with a low sampling rate of about 59 kHz. The hardware and processing requirements are modest and fast due to the simple identification algorithms and sensor structure. Localisation of the objects can be achieved with range error of about 2 mm and bearing error of less than 1/spl deg/. The sensor has been applied to localising a robot in a known indoor environment using 3D natural features and has achieved accuracies of 1 cm in position and 2/spl deg/ in bearing.