The Design Of Acquisition System For Nondestructive Testing Device And The Research On Data Preprocessing

As one of the top five transportation industry,Oil and gas pipeline transportation,regarded as country's energy blood,have been playing a quite important role in Chinese national economy.With economic development,our country's demand of oil and gas energy is increasing,leading to the pipeline has been constrcted more and more long.However,pipeline prones to leakage and explosion with the increase of in-service time and a variety of quality problem,corrosion,or exogenic action,which can cause environmental pollution,life-threatening and heavy economic loss.In order to ensure the safe operation of oil and gas transportation,oil and gas research nondestructive testing device is of great significance.Two important research of the nondestructive testing are nondestructive testing device development and data processing studying,which are the important prerequisite and foundation of pipeline accurate damage assessment and life prediction,having important practical significance.The paper designs a data acquisition system of nondestructive testing device and studies the data processing algorithm.The paper contains the following four main parts.Firstly,putting forward a complete set of hardware design for the data acquisition system of nondestructive testing device,from data collection,transmission to the processing and storage.This design of the system's master controler uses FPGA as the core.The master controler was designed by using abundant FPGA's resources of logic,programmable I/O ports and compositive IP cores.Acquisition circuit chooses DSP as the core and was designed basing on DSP's high performance and rich integrated peripherals.Secondly,for the data acquisiton from long pipelines appearing baseline wandering,the paper designed a variable scale structural element suitable for acquisiton data and useed a multi-scale morphology filter to separate the baseline from the row signal,which can also achieve normalization between different channels.Finally,in the paper,the lifting wavelet transform,the second generation wavelet transform,was used to data deniosing.Furthermore,the acquicition data processed by the treditional wavelet threshold function causes defects signal distortion.The paper improves the threshold function by adding morphology to retain the whole coefficients of the defect signal,which can reduce the damage degree of the defect signal.