Measurement of 3-D position and orientation of a robot using ultrasonic waves

A system for measuring the 3-D position and orientation of a robot hand using ultrasonic waves is proposed. The principle is a triangulation using distances between transmitters attached to a robot and receivers placed around the robot´s work space. An electric spark discharge which works as a nondirectional point source of ultrasound is used as a transmitter. This system is simple and economical compared with that using laser beams or light-emitting diodes. The accuracy is good because it measures distances directly from the transit time of an ultrasonic pulse. The relationship between the accuracy and the number of receivers is discussed, and the possibilities of automatic tracking of a moving transmitter are examined