METHOD OF ULTRASONIC PHASE TWO-COORDINATE INFORMATION REGISTRATION FOR AUTOMATED NON-DESTRUCTIVE TESTING SYSTEMS

Abstract

The article is devoted to the issue of improving the coordinate registration of information in means of automated non-destructive testing. Existing systems of non-contact registration of spatial position sensors of non-destructive testing are mostly focused on the use of signal fields of different physical nature, for example, acoustic or optical, which are created around the position of these sensors and amplitude methods of signal processing. These methods do not provide the necessary accuracy of determining the coordinates in the case of using small-aperture sensors of non-destructive testing.
 The basis of the proposed technical solution is the trilateration method. The distance between the emitter of ultrasonic vibration, which is structurally connected to the sensor, and the two receivers is determined by the phase method. This method provides increased accuracy in determining the coordinates of the sensor. Eliminating the ambiguity of phase measurements is based on the combination of the multi-frequency method and the numerical system of residual classes. This makes it possible to minimize the probability of incorrect resolution of the ambiguity of the results of phase distance measurements and to ensure high accuracy of coordinate determination (with an absolute error of the order of mm). The idea of the method and the main calculation formulas that make it possible to determine the modules of the numerical system of residual classes and the values of the operating frequencies of ultrasonic oscillations are presented. Matching the discretes for determining the phase shifts of signals with the modules of the numerical system of residual classes at different operating frequencies makes it possible to reduce the resolution of the ambiguity of the results of phase measurements to the task of restoring integers in the positional counting system from their representation by residuals in the numerical system of residual classes. The mechanism of occurrence of gross errors in the recovery of whole numbers is considered. An algorithm for eliminating this error is proposed. In general, the correctness of the algorithm for determining the sensor coordinates is confirmed by the simulation results. The considered method of two-coordinate information registration can be used both in the development of new automated means of non-destructive testing, and for the improvement of existing ones, which involve a manual method of scanning the surface of testing objects.