指针式压力表自动读数系统设计

为了降低人工读数带来的误差，设计了一个用于指针式压力表自动检定的自动读数系统，该系统主要由CMOS彩色摄像机、DOME光源和计算机三部分构成。DOME光源主要用来降低外界对摄像机拍摄的指针式压力表图像的影响。摄像机获得压力表图像后经USB数据线传输到计算机，计算机首先对图像进行二值化处理，其次，利用Hough变换提取表盘的中心点，再次，利用连通区域标记提取指针和刻度线，最后根据指针和相邻的两条刻度线位置关系并根据刻度线所对应的示值计算出表盘指针对应的刻度值，从而完成自动读数。经实际压力表测试，该系统能够在较短时间内准确读出压力表的示值，极大地解放了劳动力，同时提高了压力表的检定效率。

Design of automatic reading system for pointer pressure gauge

In order to reduce the error brought by human reading, an automatic reading system for pointer pressure gauge was designed, which was used for automatic verification of gauge. The system consisted of CMOS color camera, DOME light source and a computer. This system used DOME light source to reduce the interference of environment for the images of the gauge. Gauge images were transferred via USB data cable to a computer. Firstly, binarization was used to the images. Secondly, hough transformation was used to extract the centroid of the gauge. Thirdly, the pointer and tick marks were extracted by connected region labeling method. Finally, according to the position relationship between the pointer and the two neighbor tick marks and their values, the value of pointer indicated was computed. Through the evaluation of actual gauges, the system can figure out the value of gauges in a short time, and it greatly liberates the labor force, while it has improved the efficiency of gauge verification.