The Design And Implementation Of Laser Spot Tracking System Based On Camera

With the development of railway in our country, especially the emergence of high-speed railway in the recent ten years, higher request of track quality has been put forward, among which the track height and smooth degree is highly related to the safety of train tracffic. However the current low efficiency of the detection of height and smooth degree cannot meet the practical needs and the accuracy of existing detection system are mostly low. The rate of maintenance of the system equipment is higher and expensive. So the method of laser non-contact measuring combined with computer vision has been designed to test the orbit height and smooth degree, which based on the serious analysis of the existing detection methods and massive references.The design philosophy of the thesis is as follows:Using the image processing technology to get pixel coordinates of laser spot center, and then through mathematical formula derivation, the variation of the center pixel coordinates are transformed to actual displacement, which camera needed. The system uses embedded motion controller to control stepping motor to realize the position of the adjustment of the camera and guarantee the spot center is always in the camera center field of view, so the function of real-time tracking of laser speckle can be realized. In the system, the data passed to the stepper motor is exactly the detection information of track level. And subsequent analysis can be stretched depended on these information.The design, based on the embedded system, can reduce the man-made interference and improve the efficiency of the system. In a word, the system has certain value not only in theory but also in practice. The main research work of this thesis is as follows.(1) Aiming at the disadvantages of existing track height and smooth degree testing system, the method of laser non-contact measuring combined with computer vision to test the orbit height and smooth degree has been designed. Based on consulting a large number of thesises and analysis, the overall structure of this system has been planned:it can be described like that OpenCV libraries have been used to process the image of laser facular and ARM development board and57BYGH7610stepping motor have been used in the control system.(2) On hardware platform, the Linux operating system (?)ransplantation work which includes the bootloader transplantation, Linux kernel transplantation and root file system has been done. And debugging work was done to find and solve the corresponding problems. (3) Platform based on USB camera that is used to collect image has been set up, and the OpenCV library has been used to process the collected light spot image. Then a relation between image pixels coordinates and camera coordinates has been deduced by the study of mathematics, on this basis, through the analysis and calculation, the corresponding relations between image pixel unit and the actual displacement of the object can be found.(4) In terms of camera motion control, drive circuit for driving a stepping motor has been analyzed. The principle diagram of the circuit and the corresponding PCB figure have been designed, welding corresponding chips and components on it, through debugging, it can ensure that the designed circuit works smoothly.Finally, the system has been debugged, and the existence questions and the resulting errors of this system has been analyzed. At the same time, the further research work which can improve the condition of system has been prospected.