Study On Automatic Monitoring System Of Bridge Based On Machine Vision

With the sustained and rapid development of national economy,bridge construction has entered a glorious period,the bridge health monitoring has gradually been in a hot research.Fast-developing of machine vision and wireless communication technology bring opportunity for development of bridge monitoring.So this paper puts forward and designs a wireless and automatic monitoring system based on machine vision,implementing long-term monitoring of strain,crack width,displacement and cable force.The followingtasks have beencompleted:1.By designing hardware of monitoring system,the system achieves the functions of wireless and collection of hardware;OPENWRT and MJPG-streamer are installed into wireless router,according to the working principle of MJPG – streamer,theory of accessing Web and mapping theory,the system realizes real-time acquisition and wireless beaming through programming on OPENWRT.2.LABVIEW is used as synthesis management software platform by the monitoring client,as LABVIEW can invoke hardware device and software and has all kinds of function,the system achieve the following modules through programming on LABVIEW,the login module contains monitoring direction,previewing image,selecting the calculation area manually,cycle timing collecting figure camera,keeping data in real time,automatic alarm,etc.various function of the monitoring client come true.3.The paper describes image correlation method and includes sub-pixel interpolation and least squares fit programmed in MATLAB,and visualization of data is also programmed in MATLAB,import these program into computation module of system,so design of monitoring subsystem which measures full strain is completed;In view of actual monitoring of bridges,the paper proposes the program of monitoring;The system is used for testing of model,the system has the data of full strain.4.The crack width is obtained by image processing techniques.After the algorithm is programmed in MATLAB,import the program into computation module of system,so design of monitoring subsystem which measures crack width is completed;In view of actual monitoring of bridges,the paper puts forward I-shaped and combining linear type and roundness the scheme of dynamoelectric guide,the problem that monitoring of the area are inconvenient,labor-intensive,incomplete and short-lived are solved;The system is used for testing of part of bridge model,the system has the data of crack width.5.The paper proposes how to calculate the center place of many laser speckle and calibration formula which can eliminate the effect of vibration and zoom lens,the paper also introduces how to calculate cable force based on frequency,after the algorithm is programmed in MATLAB,import the program into computation module of system,so design of monitoring subsystem which measures vibration displacement is completed;what’s more,for vibration displacement of the pylon,cable force,deflection of beam and deformation of bridge pier,the paper proposes the monitoring program which solves the problem how to place collecting device.Finally,the system is used for vibration test which three different diameter steel wire are stretched by different pull;the monitor effect of system is validated.