A multifrequency FM-based ultrasonic system for accuracy 3D measurement

This paper introduces an ultrasonic 3D position measurement system that will estimate the location of a wave source by triangulating its position based on a multiple-frequency continuous wave (MFcw) to three receivers fixed to an inertial frame of reference. The typical application of this system is finding the location of the transmitter that may be fixed on a CNC machine or robot. The receivers have to be fixed in specific locations, the major source of the problems are at the installation/calibration stage since the receivers are usually distributed in space and finding their exact location entails using a separate 3D calibrating device which may not be as accurate as the location system itself. This paper presents a method to use the system itself to set up an inertial frame of reference and find out the locations of the receivers.