The Study Of Image Capture And Pre-processing System Applied On Narrow Gap SAW

It is required that the welding arc must be kept in the center during narrow-gap SAW, In order to meet this demand , the automatic welding beam tracking system is introduced . Currently, there are various types of automatic welding beam tracking system based on different sensors , but one type of them is highly superior ,which is the optical sensor based automatic welding tracking system . Image capture system is a important component of optical sensor based automatic welding tracking system, which function is to receive the image data from the camera, after pre-processing these data, transfer them to the computer ultimately. After the computer does the post-image-processing and feedbacks the magnitude of welding arc deviation to the mechanical control system, the automatic tracking achieves. so correspondingly we can say that the accuracy, definition and speed of the image capture system is crucial to the welding beam tracking .The image capture system mainly consists of two parts, which are optical structure and the image capture card. The optical structure is taking shape by installing the light source and optical sensor in a specific way. The image capture card is designed according to the particular applying circumstance. The key design of the whole image capture system is on image capture, because the image capture card is specifically for narrow gap SAW, the design mainly relies on the characteristics of narrow gap welding beam and welding circumstance . The image capture card choses FPGA to be the core processor for logic control and image pre-processing materialization, which not only makes the design highly flexible, but makes the circuit efficiently brief. For connecting the digital camera, adopts the extensively used camera link to be input of the image capture card, which improves the commonality, data transport speed and anti-interference ability. Adopts the PCI bus to be the output of the image capture card, to connect the card and the computer, which obtain the high speed and accuracy of data transportation. First section is the optical structure design of image capture system. This section explicitly illustrates the way of choosing and installing the light source, and the way of how it can implement the welding beam image capture with optical sensors. The second section is the design of image capture card, and it is the key work of this paper, which includes the hardware and the software design of each. At last we illustrate the testing of the image capture card on computer, and according to the characteristic of welding beam, we study the method of image pre-processing. Due to the impact of welding arc,welding splash,welding fume in the welding process, we use the image enhancement,smoothing filtering, thresholding to process the image, finally acquired the welding beam image with conspicuous characteristics and small data volume.