Design And Implementation Of Shield Tail Voids Measurement System Based On Computer Vision

In recent years, the shield machine is widely used in the underground construction. Full name of shield machine, shield tunnel, is a kind of tunnel as special engineering machinery, tunneling modern shield tunnelling machine and optical-mechanic-electric fluid, sensing, information technology at an organic whole, with soil, conveying soil excavation cutting ballastleas, assembles tunnel lining, measuring orientation deviation, and other functions, involving geology, civil, machinery, mechanical and hydraulic, electric, control, measurements, and multi-discipline technology according to different geological undertake "tailors" type design and manufacturing, high reliability requirements. Shield tunnelling machine widely used in the subway, railway, highway, municipal, utilities and other tunnel project. The gap of the shield tail is one of the important parameters used to be controlled in the construction. The gap of the shield tail is the gap between the internal diameter of the steel ring of the shield tail and the external diameter of the segment, because of the difference of the push Jack'push length and the earth strength or other factors, the gap of the shield machine varies in the construction. When the gap exceeds the allowable limit, the brush of the shield tail will be worn quickly and the segments will be fractured and so on. So the gap of the shield tail needs to be measured real-time in order to adjust the pushing posture of the shield machine. In current shield constructions, the gap is mainly measured by manual, but the manual measurement can bring bigger error and some construction safety questions. For the backward of measurement issue, this paper researches a non-constant measuring system which is based on image processing technology to measure the gap of the shield machine. This measuring system only needs the operator click the'measure'button, it can automatically measure the gap and have a simple analysis of the measurement. The research of this system can help to improve the safety and accuracy of the shield construction, and promote the automation of the construction.This measuring system of the gap of the shield tail, mainly composed by hardware and software, regards the technology of image processing as basic principle. The hardware is used to collect the images of the shield tail; The software is used to detect the edge of the shield tail'segment and the shield tail calibration points by a variety of image processing algorithms and calculate the gap of the shield tail.Hardware is mainly composed by CCD camera, light, laser, acquisition card and computer. Based on the basic principles of optical imaging, the system used light to provide sufficient brightness in the shield tail, the CCD camera collect images of shield tail. Acquisition card is mainly in charge of changing the analog signals which is transferred by the CCD camera into digital signals, then provides them to the computer to process. Meanwhile, it is needed to provide the calibrated points by setting the laser at the end of the shield tail.The software component is mainly including the research of algorithms and procedures. By the Matlab experiments and the analysis of the images of the gap of the shield tail the reasonable algorithm process of the processing of the images is determined, which is mainly composed by median filtering, thresholding, Canny edge detection and Hough transform and so on. In order to extract laser calibrated points, a new method of colorful image processing based on RGB model is discovered. The experiments indicate that this method can better extract the focus of the laser calibrated points. The development platform of the program is based on VS2008, and call OpenCV image processing library to complete. It is mainly composed by the parameter settings, image acquisition, image processing, calculate and check modules and so on. This program can basically realize the required functions such as acquisition, processing and query.Shield the realization of the tail voids measurement system from artificially measurement shield tail voids brings the method behind and may have big error, and construction safe hidden trouble, so as to realize the real-time automatic measurement shield tail voids, adjust the shield machine development direction. In actual application of application of the system achieved good effect.Finally, the measurement system is analyzed and summarized by the end of this paper. The direction and methods of further improvement are also raised.