Research On Measuring System For Automotive Products Based On Vision Measurement Technology

With the rapid development of science technology, people's demands for qualityare higher and higher than before. For automotive industry, the quality of automotiveproducts will affect the performance of vehicle directly. So, it is very important tomeasure the parts precisely. Normally, manual measuring will not only affect theefficiency of production, but also bring in some factors which are not reliable, and itwill be related to the quality and the cost finally. However, most procedure not onlyneed measuring the extrinsic feature of products, also need some precision data, suchas the width of products, the dimension of the hole, the coordinate of the base pointand so on. And these data need to be tracked. But, these work can not been donequickly by workers'eyes, besides, it will be injured if using the method of contactmeasuring, and it will be useless for real-time measurement. But, these problems canbe solved by using a technology of vision measurement. And more important is that itcan be realized the system automation to streamline production by using visionmeasurement. Nowadays, during the procedure of modern automotive industry, thevision measuring technology has become one of key technologies in the productionprocess. This application of vision measurement system can eliminate the substandardproducts in production line, and the function of qualitytracking will be realized.In this paper, the author select spark plug measurement as research entity, andextend the measure method which based on vision measuring technology. As is knowto all, spark plug is one important parts of the engine, which mainly includemechanical holder, insulator parts, center electrode and grounding electrode. Thedimension between center electrode and grounding electrode of spark plug is animportant index to weight its ignition effect. So, it must be measured precisely before be delivered to the market, to ensure the quality, and keep the dimension in thestandard range. And these data must be tracked. That's the reason why manualmeasurement could not follow up the steps of modern industry. This vision systemcan not only realize the function of noncontact and online measuring to get the detailparameter information, but the quality of the spark plug can be tracked. And thissystem is built to improve the accuracy and speed for measuring and reduce the laborintensity.In terms of the paper structure, the author deeply researched the scheme of visionmeasurement system and its hardware and software design. Meanwhile, have adetailed analysis on the platform of image processing, the algorithm of edge detectionand the communication between image processing platform and field device. Andfinally, it realized the application of vision measuring system in spark plugmeasurement system.The keypoints are:1. Research the measuring principle and the measuring flow of this vision system,and build up the mathematic model, to establish the theoretical foundation of thevision system.And guide the design of scheme which behind.2. Research the system scheme. First, this paper will have a brief overview on thesystem, and then raised three hot issues for this study, they are: How to choose thetypes of image processing platform? How to choose the edge detection algorithm?How to deal with the data communication between the platform and PLC device?Finally, make a right decision though comparative analysis.3. Research the system hardware. First, this paper will present a systemframework which based on TMS320DM642 DSP chip, and then divided this systeminto several parts, such as: power part, memory part, video encoder and decoder partand communication part. At last, deeply research on interface circuit of these partsanddetail information about the pin distribution of these chip.4. Research the system software. This paper will study the main program flowchart and other interruption subroutine flow chart according to the measuring flow ofthis vision system, combine the system scheme, such as: the image acquisition, theimage processing, the communication with other external device and self-bootingsystem.