The Research Of Bomb Surface Flaws Detection System Basing On The Digital Image Processing Technique

The nondestructive detection is a kind of special measuring technique. The objects'physical variables can be changed by the physical character which exists the flaws or the difference in the organization structure. On the condition of without destroying the object's usability and the formation, with measuring these physical variables can we know and value the feature, state or inner structure of the material, product and equipment part. At present, there are many nondestructive detection methods in the industry, such as: ultrasonic test (UT),magnetism dust test (MT),electron test (ET),acoustic emission test(AE),leakage test (LT),percolation test (PT),ray test (RT),neutron ray test (NRT),visual test (VT etc. With the development of the image processing technique and computer technique, more and more people use the measuring methods which base on the image processing. The paper introduces the application of image processing and image analysis techniques in MT system. Practice also, process that MT is one of all the effective methods that is widely utilized to detect bomb surface flaws. But MT is usually practiced through the eyes of the operators by identifying the test results and pointing out the defects, which is quite low in the automation level and productivity. Meanwhile it's impossible to recall the test results. Moreover, there is a great deal of unsafe factors existing. As a result , it is of great importance to introduce and utilize the computer techniques ,communications techniques, data image processing and analysis techniques in order to serve the functions ,such as obtaining information ,transferring information, processing information, controlling information and so on ,which can realize the automation of bomb surface flaws detection. The system is constructed of the cameras, corresponding sense organ, image sampling cards, computer, display device, printer, annunciator and control system etc. According to the detection demands of the examined objects and the technical requirement, we can choose the cameras (including the resolution, amount, linear camera, frame camera etc). The image signals acquisitioned by camera transmit to the computer to be processed through suited image sampling card. Simultaneously, the signals of object rotate speed acquisitioned by the sensors are sent to computer to be processed, then the computer controls the parameters of sampling speed etc according to the result .On the hand, according to the actual demands, computer may be connected to the display device, printer, memory storage etc. After the computer processes and analyzes the image signals acquisitioned by the image sampling card, it can get useful information which can control the annunciator, and transfers correlative controlling signals to the external controlling equipment (programming logic controller (PLC) etc). The system chooses DS-44-04M30 standard digital camera, which is produced by Canadian DALSA Company. The camera can satisfy the minimum accuracy (0.5mm) demands of the system, and high-sensitivity ,four-channel data outputting can make the data transfer rate reach 160MB/s,which also satisfy the real-time demand of the system . The data sampling card is produced by Canadian CORECO Company. The Viper-Digital card, which can cooperate well with the camera and receive all kinds of digital image signal in common data mode through four channels, which can be transfer to the host computer or other special image processing card. We can also embed a pixel processor to make a high-speed and real-time process of the image. We choose CPM1A-40CDR-1 PLC produced by Japanese OMRON Company as the CPU of the Magnetism-particle machine, which can satisfy the demand of the system .It also has a lot of advantages such as compact structure and convenience in operating. The paper discuses abut the principles of digital image processing which is a the processing mode we choose in the auto detection system of the flaws on the surface of the bomb .it also mentions MATLAB emulation and analysis. The principle mainly includes: image smoothing, image sharpening etc. In the introduction of the processing modes of image smoothing ,we illustrate the different modes such as : histogram equalization,smoothing linear filtering and order-statistics filtering,while in the section of image sharpening we expound gradient and Iaplacian operator. Moreover ,the author also elaborate target identification principle and the modes we choose in the nondestructive detection system .The principle of target identification mainly introduce edge detection and threshold processing etc. In the part of processing the author explains first derivative gradient and second derivative laplacian operator, in addition to the advantage and the disadvantage of that. In the threshold processing modes, the principle of global threshold, optimal threshold etc is discussed .In the explanation of image edge detection techniques, MATLAB emulation program, results and analysis has been elaborated in details.