The Research On The Focus Technology Of Industrial Inspection Ultrasonic Phased Array

Ultrasonic phased array system receives ultrasonic echoes and realizes beam deflection,focusing by controlling the array element excitation sequence of the phased array probe,thereby realizing rapid and efficient detection of the measured workpiece.The key technology in the ultrasonic phased array system is to control the timing of transmission,reception and synthesis to obtain a high-quality sound field.Phased array synthesis focusing techniques include dynamic focusing,dynamic apodization,dynamic aperture,and so on.This paper focuses on the principle of ultrasonic phased array synthesis focusing technology,proposes a method to improve the resolution of conventional focused beam and FPGA-based synthetic focusing algorithm design,and finally verifies that dynamic focusing and dynamic apodization techniques improve spatial resolution on the superiority.Main work and achievements in the dissertation are as follows:1.Discussion of the basic principle of ultrasonic phased array.Ultrasonic sound field theory and detection principle,phased array detection principle are studied,including the calculation of the deflection and focus delay parameters.Furthermore,the sound field is simulated based on the algebraic calculation of the focused sound field.Meanwhile,a variety of algorithm principles and methods for improving the sound field of ultrasonic phased array focusing are discussed.2.Simulation-aided design for focusing algorithm.The sound field simulation is established by analyzing sound pressure distribution.The resolution of different focusing algorithms in defect scanning imaging is studied by simulation.An imaging algorithm suitable for ultrasonic phased array digital system is selected based on the simulation results.3.FPGA-based design for a synthetic focusing algorithm.A beamforming method based on FIR filter that can achieve 2.5ns accuracy is designed by analyzing the characteristics of ultrasonic phased array digital system.This paper designs a method of beam synthesis that requires less buffer,and inserts the real-time focusing algorithm into the synthesis module.Dynamic focusing and dynamic apodization are implemented with a small amount of logic resources.4.Test of the synthetic focusing algorithm.The designed focusing algorithm module are spliced into the ultrasonic phased array digital system for debugging analysis.The improvement of the resolution of the system by the synthetic focusing algorithm is verified.