【摘要】：由于指針式儀表結(jié)構(gòu)簡(jiǎn)單,而且還具有防水、防塵、防電磁干擾等優(yōu)點(diǎn),所以在石油工業(yè)領(lǐng)域中,指針式壓力表有著很廣泛的應(yīng)用。在指針式儀表讀數(shù)識(shí)別中目前主要還是以人眼觀測(cè)為主,為了提高檢測(cè)的快速性、準(zhǔn)確性和高效性,本文針對(duì)石油工業(yè)中常用的指針式壓力表,設(shè)計(jì)了一個(gè)自動(dòng)識(shí)別壓力值的系統(tǒng)。該系統(tǒng)主要是通過機(jī)器視覺,利用圖像處理技術(shù)自動(dòng)得出壓力表示值。本系統(tǒng)采用500萬像素的CCD相機(jī),先將采集到的儀表圖像預(yù)處理,主要包括三個(gè)步驟:首先通過中值濾波來去除表盤圖像中的椒鹽噪聲,同時(shí)也能很好地保存圖像邊緣部分;然后采用分段線性變換來增強(qiáng)指針和刻度線等重要感興趣部分的信息;最后利用Canny邊緣檢測(cè)儀表圖像的邊緣,根據(jù)表盤的形狀和位置等特征提取出儀表表盤的邊緣,并通過該邊緣擬合出的圓分割出含有指針和刻度線的表盤輪廓。通過預(yù)處理得到了感興趣的表盤圖像,然后就只需確定指針和刻度線的位置關(guān)系即可確定壓力表示值。由于本文研究的耐震壓力表的刻度線前后分布是不均勻的,并且儀表里面的阻尼液遮擋了部分刻度線,傳統(tǒng)的角度法或者是距離法不適用本系統(tǒng)。本文提出了圖像歸一化算法,通過改進(jìn)的平面二維插補(bǔ)算法,限制插補(bǔ)搜索的起始和終點(diǎn)角度,去除表盤圖像中的文字標(biāo)識(shí)并將圓形表盤圖像轉(zhuǎn)化成矩形圖像。然后通過指針處于不同位置處的兩幅儀表圖像制作出無指針的刻度線表盤模板,并將其拼接處融合并平滑,將該表盤模板利用zhang細(xì)化算法處理得到單像素的刻度線模板,以便刻度線精確定位。將單像素表盤模板通過改進(jìn)的霍夫直線變換檢測(cè)出刻度線,并根據(jù)刻度線位置關(guān)系補(bǔ)全出被遮擋的刻度線,這樣即得到了完整的刻度線模板,同時(shí)將每個(gè)刻度線的橫坐標(biāo)值記錄并保存到數(shù)組中。最后將采集到的儀表圖像與刻度線模板圖像通過差影法得出指針的位置,依據(jù)前后段刻度的不同分度值與指針和刻度線之間相對(duì)應(yīng)的位置關(guān)系,利用距離法最終得出指針式儀表的讀數(shù)。本系統(tǒng)最終將所有識(shí)別算法集成到MFC應(yīng)用程序,并根據(jù)指針式儀表校驗(yàn)規(guī)則,該程序采用模塊化設(shè)計(jì),主要包括三個(gè)模塊:注冊(cè)模塊、識(shí)別模塊和分析記錄模塊。通過圖像處理算法識(shí)別的壓力表示值與數(shù)字精密儀表讀數(shù)的比較分析,生成壓力表的校驗(yàn)報(bào)告。
[Abstract]:Because of its simple structure and advantages of waterproof, dustproof and electromagnetic interference, it is widely used in the field of petroleum industry. In order to improve the speed, accuracy and efficiency of the detection, this paper aims at the pressure gauge commonly used in the petroleum industry, which is mainly based on the human eye observation in the recognition of the reading of the needle meter, in order to improve the speed, accuracy and efficiency of the detection. An automatic pressure recognition system is designed. The system is mainly through machine vision, using image processing technology to automatically get the pressure gauge value. In this system, 5 million pixel CCD camera is used to preprocess the collected instrument image, which includes three steps: first, the salt and pepper noise in the dial image is removed by median filter, and the edge part of the image can be saved well; Then we use piecewise linear transformation to enhance the information of important parts of interest, such as pointer and scale line. Finally, we use Canny edge detection to detect the edge of the instrument image, and extract the edge of the meter dial according to the shape and position of the dial. The contour of dial with pointer and scale line is segmented by the circle fitted by the edge. The interested dial image is obtained by preprocessing, and then the pressure gauge value can be determined only by determining the position relationship between the pointer and the dial line. Because the distribution of the scale line of the seismic pressure gauge studied in this paper is not uniform, and the damping liquid in the instrument blocks part of the scale line, the traditional angle method or the distance method is not suitable for this system. An image normalization algorithm is proposed in this paper. The improved planar two-dimensional interpolation algorithm limits the starting and ending angles of interpolation search, removes the character marks in the dial image and converts the circular dial image into a rectangular image. Then, the dial template without pointer is made by two instrument images at different positions, and the splicing place is fused and smoothed. The dial template is processed by zhang thinning algorithm to get the scale line template of single pixel. So that the precise positioning of the dial line. The single pixel dial template is detected by improved Hoff line transformation, and the occluded scale is completed according to the position relation of the scale line, thus the complete scale template is obtained. At the same time, the horizontal coordinate values of each scale are recorded and saved to the array. Finally, the position of the pointer is obtained by using the difference shadow method between the collected instrument image and the scale template image, and the corresponding position relationship between the pointer and the scale line is obtained according to the different indexing values of the front and rear segments of the scale. The distance method is used to get the reading of the pointer meter. Finally, the system integrates all the recognition algorithms into the MFC application program, and according to the verification rules of the exponential instrument, the program is designed by modularization, which includes three modules: registration module, identification module and analysis record module. The calibration report of the pressure gauge is generated through the comparison and analysis of the pressure representation value recognized by the image processing algorithm and the digital precision meter reading.
【學(xué)位授予單位】：湖北工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TP391.41

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本文編號(hào)：2203011