Measurement of 3-D Position and Orientation of a Robot Using Ultrasonic Waves (2nd Report)

Abstract

Nowadays precise estimation of performance characteristics of a robot is being necessary. An ultrasonic measuring system of 3-D position and orientation of a robot for this purpose has been already proposed, of which principie is a triangulation using distances between transmitters attached to a robot arm and receivers placed around the work space of the robot. An electric spark which works as a non-directional point source of ultrasound is used as a transmitter. In this paper the development of this transmitter is dealt with. By inserting a condenser of a few hundred picofarads to the secondary side of an ignition coil in the electric circuit of the transmitter, the sound pressure of the radiated ultrasonic pulse becomes about ten times as stron3 as the case in which the condenser is not inserted. The directivity of this transmitter was investigated experimentally. An ultrasonic ranging system which uses this transmitter was also developed and causes of the ranging error were discussed.