Study And Design On γ-ray Measuring Thickness Instrument With Nios II

Along with industrial automation changing with each new day,γ-ray thickness gauge taken as a branch of the isotope measuring appliance also more and more plays the vital role in the industry on-line production survey.γ-ray thickness gauge is composed ofγ-ray sources, detector andγ-ray measuring instrument .γ-ray measuring instrument is the emphases of study.At present, the majority of domesticγ-ray thickness gauge uses SCM control systems, but this traditional method has some flaws: because of limited electronics circuit, one kind of model instrument usually only can measure some kind of material, also the calibration is complex, therefore its application is limited; As a result of clock frequency of SCM is not high, it causes limited data gathering and processing speed. In order to overcome these questions, the design adopts large-scale programmable logical component FPGA and Nios II soft kernel processor in stead of SCM to realize the data acquisition and processing control. This kind of structure has very many merits: First, because of inserting the C language in the Nios II soft kernel processor system, the measuring appliance can directly realize arithmetic of thickness measure, thus it could avoid the complex calibration and realize thickness measure of many kinds of the matter (steel plate, aluminum sheet and so on), and its generality is enhanced heavily; Second, all modules of FPGA is completed by the hardware, its reliability is higher than the SCM system, and the system stability is improved.Topic content includes two aspects: First, hardware design ofγ-ray measuring instrument system, which completes the overall structure designation (FPGA+SRAM + Nios II soft kernel processor), the design of periphery circuit and manufacture of circuit board; Second, software design ofγ-ray measuring instrument system. In the software design, the paper builds the Nios II soft kernel processor system through Qaurtus II and Nios II development software, and uses C language to complete the user program development.The system debugging and the experimental result indicates that in the thickness measurement of many measured material, the most relative error don't exceed 4% in the measuring scope of 1mm-12mm(millimeter), moreover in the long time,γ-ray measuring instrument system works stably. This kind of new measuring instrument not only reduces the cost, but also improves the data acquisition speed, the stability and the versatility.