System Design Of Digital Ultrasonic Thickness Measurement

Ultrasonic thickness measurement is widely applied to machinery manufacturing, powerindustry, agriculture, national defense, petrochemical industry and other fields for itsadvantages of a wide range of thickness detection, high sensitivity, high efficiency, low costand no harm to human body. The minimum resolution of the existing ultrasonic thicknessmeasurement system can reach0.001mm, however, the existing system is very expensive.Besides, its accuracy of measurement will be reduced and its measurement error will increasewhen the detected object has a rough surface resulting in bad echo signals which the systemreceives with a lot of noise. This article introduces a new design for thickness measurement.This design controls a high speed A/D sampling chip with FPGA and uses a new thicknessmeasurement algorithm to ensure that such a system can achieve a high precision in ultrasonicthickness measurement with minor errors even in a noisy environment.The hard design of the system this article introduces uses high-precision, low-noisecomponents to ensure high accuracy and low noise when the ultrasonic is transmitted andreceived and when the data is acquired. A excitation signal with a certain repetition frequencyis generated with the control of FPGA. This signal excites the ultrasonic transducer togenerate an ultrasonic signal applied to thickness measurement. And the echo signal will beconditioned including limiting, amplification, selecting control and adapts to A/D sampling.This design is based on digital filtering, using a spectrum zoom algorithm to extract the phaseof the transmitted signal and the echo signal.The design acquires some test datum from different objects, and analyses these datum toverify the new system’s accuracy. In general, this system runs stably and can detect thicknessreliably. It is a valuable design which will be applied to ultrasonic thickness measurement.