Study On Off-surface Displacement Measurement Of Single Camera Based On Digital Image Processing Technology

Since the reform and opening up,with the continuous development of infrastructure construction in China,more and more Bridges have been designed and built continuously.However,behind this brilliant achievement,more and more Bridges have been damaged after long-term operation and use,which requires safety detection,maintenance and reinforcement management.The traditional bridge detection method is mainly to install wired and wireless sensors on the structure to be measured,but it can't be easily measured in some large structures that are hard to access,and it is also limited by the number of hardware interfaces.Digital image processing technology has many advantages such as full scale of surface,non-contact,high density,less-time,low cost and easy to operate,as well as the characteristics of high precision.In this paper,study on off-surface displacement measurement of single camera based on digital image processing technology,describe the principle and flow of digital image edge detection technology in detail,do the static and dynamic load test of four-point simple-supported steel plate model by using three methods of finite element modeling calculation,traditional detection method and digital image processing technology to verify the accuracy and feasibility of the method.The main research contents and results of this paper are as follows:(1)Introduces the research background and significance of this paper,refer to relevant literature and materials at home and abroad,and summarizes the development of digital image processing technology,research status at home and abroad,structural modal analysis and application.(2)Introduces the main process of the experiment,and describes in detail the basic principles of digital image edge detection technology used in the experiment,including mathematical representation and characteristics of digital images,digital image acquisition and processing,digital image preprocessing,digital image target tracking and displacement calibration,etc.(3)Adopts symmetrical graded loading of four-point simple-supported steel plate as the model,with the basic principle of digital image edge detection technology as a theoretical basis for experimental analysis,introduces the off-surface displacement measurement process of single camera based on digital image processing technology,measures the deformation of the model nine measuring point data,the data compared with the finite element modeling calculation and dial indicator measurement data,proved that the data is reliable,measurement precision is enough to meet the needs of the general engineering.(4)With four simply supported plate as a model for the vibration test and research,the first calculation of finite element modeling,in order to get the model before the frequency and vibration mode,and as a reference by finite element calculation results,the traditional modal analysis based on the acceleration sensor test to carry on the design,through analyzing model was measured in three working conditions,and data integration,acceleration sensor measurement of the first five frequencies and mode shapes.The off-surface displacement measurement of single camera based on digital image processing technology is applied to the modal analysis test of the model,and the obtained results are in good agreement with the measured results of the acceleration sensor.(5)Summarizes the work and research results of this paper,and look forward to the future research work.