Research On 3D Calibration Echnology Of Nondestructive Detection Image Based On Ultrasonic Phased Array

In industrial non-destructive testing,compared with traditional two-dimensional ultrasound imaging technology,three-dimensional ultrasound imaging can more intuitively and accurately obtain the spatial position,size and shape of defects of the tested material,providing a reliable way to further repair and diagnose defects.in accordance with.In aircraft skin defect detection,three-dimensional ultrasonic calibration is an indispensable step for defect detection and is the basis for subsequent spatial three-dimensional reconstruction.This paper focuses on the three-dimensional ultrasonic phased array calibration technology for non-destructive testing of aircraft skins.The related principles and basic theories of ultrasonic phased array imaging are described.Then the three-dimensional ultrasonic calibration technology is discussed and discussed.Experiments and analysis and comparison of accuracy.The main content and results of this article include the following aspects:First,based on the imaging principle of ultrasonic phased array non-destructive testing,theoretical analysis and method demonstration and selection of three-dimensional ultrasonic calibration technology were performed.According to the familiarity and mastery of the ultrasonic phased array non-destructive flaw detector detection principle,the current thinking of various calibration methods and the phantom used are studied,and the ultrasonic calibration operation process,calculation methods,and accuracy evaluation are carried out.Analyze and compare various calibration methods and applicable scopes,adopt Euler angle as the coordinate conversion method,select NDI optical locator to assist in positioning,obtain the target position from the probe tip point and apply the improved 3D LM algorithm to the phantom calibration.Second,based on the research and comparison of various calibration phantoms and corresponding calibration methods,a simplified point-based multi-target phantom and its ultrasonic calibration method without calculating the phantom position in advance are designed.The calibration makes full use of the advantages of the optical positioning system and the point phantom,and obtains its true coordinate position by positioning the probe directly contacting each point target without additional calibration to obtain the phantom position.This reduces the introduction of errors,and also simplifies the calibration operation process and calculation formulas.Fewer images need to be collected,the phantom structure is simple,and the calculation efficiency is high.At the same time,the existing double-layer N-line phantom operation process has been improved.The characteristics of the N-line are used for scanning and calibration through unidirectional moving ultrasonic non-destructive testing,which is convenient and fast.Third,the ultrasonic calibration system for ultrasonic phased array non-destructive testing images performed calibration experiments on the new multi-point simplified phantom and the traditional N-line phantom,compared and analyzed the calibration accuracy,and performed 3D reconstruction and error analysis of the experimental results.The overall framework of a three-dimensional ultrasonic phased array calibration system was constructed.Ultrasonic images were acquired by driving a six-degree-of-freedom robotic arm to hold an ultrasonic non-destructive flaw detector to scan and realize automatic image acquisition.Defect segmentation technology is used to implement dynamic image tracking,and ROI region extraction technology is used to extract pixel coordinates of the image to achieve dynamic processing of the image.The three-dimensional ultrasonic calibration system established on the MATLAB platform was used to perform experiments on the double-layer N-line phantom and the new simplified multi-target phantom.The calibration accuracy of the two phantoms was analyzed and compared respectively,and three-dimensional reconstruction was performed.The experimental results show that the calibration error of the N line is less than 2mm,and the reconstruction accuracy is 1.38 mm,which meets the current detection requirements.The reconstruction accuracy obtained by the new multi-point simplified phantom is 0.29 mm,and the calibration reproducibility in all directions is less than 0.19 mm.Compared with the traditional phantom calibration method,the accuracy has been greatly improved.Strong superiority.