High Speed Detection Method Of Cylinder Block Surface Defects Based On Images

There will always be a need to detect certain objects in many industries, especially those involving people’s life and safety. Thus a variety of detection techniques suitable for all industries were derived. A variety of detection methods had emerged in the detection of surface defects of metal parts. Here, parts surface defect detection method based on machine vision and digital image processing technology were studied systematically by combining with the project which was detecting the main hole of automobile brake master cylinder. In recent years, there was much research on this method, and it had promoted its application in various fields. A method making the collected images of the parts surface as the medium and achieving the goal of detection by corresponding image processing has the advantages which other detection technologies have not such as non-contact, real-time online, the appropriate speed, precision and the scene has strong anti-jamming capability. Therefore, it is very necessary to study and further research. The main research contents of this paper include the following aspects:First, the article expounded the background and significance of the research, introduced the various detection methods of the surface defects of the parts, and summarized the research results and the status quo of the domestic and foreign digital image defect detection technology.Second, this paper introduced the various instruments and equipments in the experiment of image acquisition in detail, and put forward an image acquisition method. In the experiment of image acquisition, many kinds of technical difficulties, such as the mobile speed control, the determination of the position of the camera, the choice of the size of the acquisition window, and so on, were met. The corresponding solutions were given in this paper.Third, a variety of image preprocessing methods were introduced and compared, which mainly included histogram equalization, median filtering, mean filtering, wavelet transform. And the best method of image processing was selected by using the classical differential operator method for the same image edge extraction and comparing the complete and continuity degree of the edge extracted by each operator. This paper determined choose Canny operator for edge detection eventually.Fourth, this paper described the application of mathematical morphology in image processing, introduces the expansion, corrosion, opening and closing operation, used these algorithms to optimize the edge of the edge extraction image, improved the edge features, and proposed a method of using the point of the object to carry on the edge.Finally, the defect characteristics were extracted from the processed image. The defect feature judgment standard was given. The perimeter and area of the defects were calculated. Then the circular degree was obtained. This paper made quantitative analysis of the defects based on these parameters and completed detecting the parts surface defect. The experiment and actual results showed that this method could detect the parts whether there was defect and the specific characteristics of the defect and its position on the surface of the parts quickly.