Study Of Universal Ultrosonic Testing Instrument Based On The FPGA And PCI

As one of the five major non-destructive testing techniques,ultrasonic testing technology has been widely used in industrial non-destructive testing.For different application,the ultrasonic testing system needs to meet different requirements.There are demands such as identificate defection intelligently,automatic testing by usingmovement mechanism,especially in the ultrasonic rapid scanning testing,high repetition rate,high-speed sampling and data transmission are required.High sensitivity and accuracy are also required.Therefore,this project developed a board-type universal ultrasonic testing instrument to meet the requirements of users to quickly build an ultrasonic testing instrument and constitute an automated ultrasonic testing system,based on the investigation of domestic and foreign ultrasound testing system.The instrument development takes FPGA as the core and adopts the modular structure design.The instrument has the following functions: the flexible pulse emission,with adjustable pulse width,pulse number and pulse repetition frequency;two working mode,which support the T/R,T/T and free to switch between internal trigger and external trigger;synchronous dynamic digital filter whose cofficients can be reload and high-speed data transmission,improve residual sensitivity and pulse repetition frequency;large gain range,with optional front 20 dB attenuation and continuously adjustable 80 dB dynamic gain;synchronous control of multi-path movement mechanism can simultaneously control the running direction,speed,and time of 3-way motion mechanism in real time.The design of the hardware circuit of the instrument includes the design of a launch circuit,a receiving circuit,a motor control circuit,and a digital control circuit.FPGA logic design using Verilog HDL hardware description language,and in accordance with the modular idea is divided into timing module,pulse transmitter module,PCI communication module,A / D,D / A module,FIR filter with dynamic coefficient module,CIC interpolation Filter module,high-speed cache module,motion mechanism control module,etc.The software uses QT programming to realize human-computer interaction,and can send ultrasonic testing parameters,motion mechanism control parameters,digital filter parameters,etc.in real time;can display,store and export of waveforms at the same time;can calculate waveform spectrum,can sweep frequency to get the best emission parameters etc.The performance testing of instrument shows that each module of the universal ultrasonic testing instrument achieves the goal and the performance meets the requirements of the design task book.The residual sensitivity before digital filtering can reach 52 dB,and the pulse repetition frequency can be increased to 14 KHz when the sampling length is 1024 words.The ultrasonic water-immersed scanning inspection system for gears with narrow seam defects using this instrument can detect flat-bottomed holes with lower gain,and meets the requirements for narrow welds and high penetration depth of gears.Instruments have become goods and been sold successfuly.