Research On Real-time Measurent Of Steel Pipe's Strghtness Based On Machine Version

Steel pipe does play a imprortant role in industry, it's applied extensively to chemical industry, metallurgy, mechanics and so on. Straightness is one of the most important technology index for steel pipe. Lots of research is made on the straightness of axis and guidway in given plane between national and foreign, but there's little research on steel pipe's 3-D straightness. It has industry value and science significance to do research into straightness measurment with high precision.The displacement sensor and guy wire are often used to measure steel pipe's straightness, which are used to evaluate steel pipe's 3-D straightness by surface busbar. So it has low accuracy and could't be realized non-contact measurement of steel pipe's straightness, only can be applied for sampling the steel pipe's straightness detection. Machine version is applied to realize non-contact measurment of the steel pipe's straightness. It has made a breakthrough in measurment method. There's no deep research on optical imaging sytem, edge detection algorithm or design of hardware circuit which are the modules of straightness real-time measurment. Based on others'research, machine version is adopted to measure steel pipe's 3-D straightness in this paper. Firstly, optical imaging system is designed for steel pipe's 3-D straightness measurment. Then, a new method of image edge detection is adopted to detect the steel pipe's edge, which is associated with steel pipe's special shape and illumination manner. Algorithm of the steel pipe's 3-D straightness calculation is also designed, which is compared with traditional method by experiment. Finally,FPGA and DSP are adopted to design the hardware circuit of straightness measurment. The main contents of this paper are as follws.In the first chapter, the research status of steel pipe's straightness measurment between national and foreign is analysed. The intention and significaion of this disseration are expatiated, and the main research work in this dissertation is introduced.In the second chapter, the optical imaging system which is applied to steel pipe's straigtness measurment is designed. Firstly, technology index of the imaging system is designed. A structure of double-Gauss lens is adopted to design the basic structure of the optical imaging system. Then, ZEMAX is used to analyze image quality and also be used to simulate the optical system. The structure parameters of imaging lens are optimally designed. It is assured that the designed system can be applied to measure steel pipe's straightness.In the third chapter, edge detection algorithm which is used for steel pipe's straightness measurment have been designed. Principles of the traditional method edge detection operato and mathematical method are analysed, and also the status of them is analysed. A new method of image edge detection named judgment of different adjacent row's gray is adopted to detect the steel pipe's edge, which is associated with steel pipe's sspecial shape and illumination manner. Finally, algorithm of edge detection is evaluated by quality and computation power.In the fourth chapter, algorithm of steel pipe's straightness measurment has been designed with experiment. Firstly, algorithm of steel pipe's pixel axis coordinate is designed. Then, Least-squares is adopted to evaluate straigtness error, and also the measurment system is calibrated. Finally, the method adopted in this paper is compared with the traditional method which is used dial indicator to measure steel pipe's straightness. And also the measurment system's error is analysed.In the fifth chapter, hardware circuit of steel pipe's straightness real-time measurment is designed. Firstly, the overall design of the measurment system has been done. Then, FPGA is adopted to realize the algorithm named judgment of different adjacent row's gray, and also the principle of the algorithm's realization is analysed with experiment. Finally, algorithms of steel pipe's pixel axis coordinate and straightness error evaluation are designed based on DSP, and also some experiments have been done.In the sixth chapter, the whole research work in this dissertation is summarized, and the issues of steel pipe's straightness measurment for further research are pointed out and the suggestions are put forward .