A low-cost ultrasonic 3D measurement device for calibration of Cartesian and non-Cartesian machines

The major obstacles to the widespread adoption of 3D measurement systems are accuracy, speed of process and the cost. At present, high accuracy for measuring 3D position has been achieved, and there have been real advances in reducing measurement time, but the cost of such systems remains high.
A high-accuracy and high-resolution ultrasonic distance measurement system has been achieved in this project by creating multi-frequency continuous wave frequency modulation (MFCWFM) system. The low-cost system measures dynamic distance (displacements of an ultrasound transmitter) and fixed distance (distances between receivers). The instantaneous distance between the transmitter and each receiver can be precisely determined.
New geometric algorithms for transmitter 3D position and receiver positing have also been developed in the current research to improve the measurement system‟s practicability. These algorithms allow the ultrasound receivers to be arbitrarily placed and located by self-calibration following a simple procedure.
After the development and testing of the new 3D measurement system, further studies have also been carried out on the system, considering the two major external disturbances: air temperature drifting and ultrasound echo interference. Novel methods have been successfully developed and tested to minimize measurement errors and evaluation of speed of sound.
All the enabling research described in the thesis means that it is now possible to build and implement a measurement system at reasonable cost for industrial exploitation. This will have the necessary performance to provide ultrasonic 3D position measurements in real time for monitoring position.