Overview of the hottest machine vision system

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Overview of machine vision system

· machine vision principles and concepts

in modern industrial automation production, it involves a variety of inspection, production monitoring, and parts recognition applications, such as dimensional inspection and automatic assembly integrity inspection of auto parts batch processing, automatic component positioning of electronic assembly lines, character recognition on IC, etc. Usually, this kind of work with high repeatability and intelligence can only be completed by the human eye. Sometimes, such as accurate and rapid measurement of small size, shape matching, color recognition, etc., it can not be carried out continuously and stably with the human eye, and other physical quantity sensors are also difficult to use. At this time, people began to consider capturing the image with CCD camera and sending it to the computer or special image processing module. Through digital processing, according to the pixel distribution, brightness, color and other information, we can judge the size, shape, color and so on. In this way, the rapidity and repeatability of computer are combined with the highly intelligent and abstract ability of human vision, which leads to the concept of machine vision. Compared with general image processing systems such as multimedia systems, machine vision emphasizes accuracy and speed, as well as reliability in the industrial field environment

· system composition, classification, development means and main suppliers of machine vision

the typical "Fuxing" EMU took the lead in realizing the global 350 km/h commercial operation on the Beijing Shanghai high speed railway. The vision system generally includes the following parts: light source, lens, CCD camera, image processing sheet b1.41 yuan (or image capture card), image processing software, monitor, communication/input and output unit, etc. The output of the vision system is not the image and video signal, but the detection result after calculation and processing, such as size data. After the upper computer such as PC and PLC obtains the detection results in real time, it commands the motion system or i/o system to perform corresponding control actions, such as positioning and classification

according to the operating environment of vision system, it can be divided into PC-based system and PLC-based system. The PC based system makes use of its openness, high programming flexibility and good windows interface. At the same time, the overall cost of the system is low. PC based system contains a high-performance image capture card, which can generally connect multiple shots and provide library function support. At present, the world's leading PC based vision system manufacturer is the American data translation company. Its Mach series (such as dt3155) and MV series PCI industrial vision cards have become industry standards. In terms of supporting software, the 32-bit SDK for windows95/98/nt provides c/c++ programming DLLs, and the DT active open layer visual control provides a graphical programming environment under VB and vc++, DT vision foundry is an object-oriented machine vision configuration software under windows. Users can use it to quickly develop complex and advanced applications. Similar companies include American NI company, which is outstanding in combining machine vision and motion control functions with the widely used LabVIEW virtual operation impact testing machine instrument software

compared with American companies' vigorous development of PC structure, Japanese and German companies are at the forefront of the PLC based system. In the PLC system, the role of vision is more like an intelligent sensor. The image processing unit is independent of the system and exchanges data with PLC through serial bus and i/o. Panasonic's image checker m100/m200 system can be said to be a representative in this regard. The system uses high-speed ASIC for 256 level gray detection, with logic conditions and mathematical operation functions. The system software is solidified in the image processor, and the menu displayed in the monitor is configured through a simple device similar to the game keyboard. In particular, the product 110/a210 embodies the characteristics of integration, miniaturization, high speed and low cost. Omron, KEYENCE and other companies also have similar systems, but the technical performance is relatively simple, which is more suitable for whether there is discrimination, shape matching and so on. Siemens' intelligent PROFIBUS industrial vision system SIMATIC vs ensures high transmission efficiency. 710 provides an integrated and distributed high-end image processing scheme, which integrates the processor, CCD and i/o into a chassis and provides PROFIBUS connection mode or integrated i/o and RS232 interfaces. More importantly, through the configuration of Pro vision software under PC Windows, vs 710 combines the flexibility of PC, the reliability of PLC, distributed network technology and integrated design for the first time, making Siemens find a perfect balance between PC and PLC systems

· typical application fields and market status of machine vision

machine vision is extremely suitable for quality inspection in the process of mass production, such as: assembly integrity of parts, assembly dimensional accuracy, machining accuracy of parts, position/angle measurement, part recognition, feature/character recognition, etc. Its largest application industries are: automotive, pharmaceutical, electronic and electrical, manufacturing, packaging/food/beverage, medicine. Such as the inspection of the processing accuracy of the automobile dashboard, the rapid positioning of electronic components on the high-speed mounter, the inspection of the number of pins, the identification of the characters printed on the IC surface, the inspection of the capsule wall thickness and appearance defects in the capsule production, the inspection of the number and damage of the balls in the bearing production, the identification of the production date on the food packaging, and the inspection of the label placement position. As well as medical judgment on the number and nature of cells. At present, the application of vision system is in the ascendant in the world, with the market size of 4.6 billion US dollars in 1998. In China, industrial vision system is still in the concept introduction period. After solving the problem of production automation, leading enterprises in various industries have begun to turn their attention to vision measurement automation

· the combination of machine vision and motion control, networking and other technologies

the vision system involves optics and image processing algorithms, and itself is a highly specialized product. However, in the whole measurement control system, it must cooperate with the motion control system to complete position correction and feed control. For example, in the high-speed chip mounter, it must cooperate with the 4-axis servo control system; In addition, the vision system must have the ability of distributed connection when carrying out synchronous and continuous detection of multiple processes on the production line. At present, the combination of machine vision, motion control, network communication and other advanced technologies is changing the face of industrial automation production, and enterprises with the technical background of motion control, machine vision and network communication will undoubtedly be in the forefront. (end)

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