Research On Wireless Positioning And IMU Integrated Sensor For Bridge Deformation Monitoring

In order to meet the requirements of constructing expressways and high-speed railways in complex terrain areas such as river-sea,canyons and buildings,a large number of bridges have been built in China.Bridges play an increasingly important role in road traffic.Because of high cost,complex construction and high maintenance costs,it is of great significance to establish a long-term and real-time monitoring system for bridge structures.Traditional geodetic technology is limited by the shortcomings of poor real-time performance,inadequate accuracy and difficult operation.In this thesis,a bridge deformation monitoring system based on satellite positioning and inertial measurement technology is designed and implemented,which implements all-weather and real-time monitoring of bridge structure information.Using differential positioning technology of GPS and Beidou system,combined with Kalman information fusion algorithm,GNSS/IMU combined positioning method is adopted for bridge deformation monitoring.The main works of this thesis are as follows:(1)The basic model of bridge health monitoring is studied and analyzed.Based on the principle of satellite differential positioning and the coordinate theory of inertial positioning,the bridge deformation monitoring method of GNSS/IMU integrated positioning is constructed,and use ZigBee wireless networking technology to network and transmit data of sensors in the monitoring system.(2)The software and hardware parts of the system are analyzed and designed in detail,including the collection of GPS/Beidou satellite receiver and IMU information,the layout methods of various sensors,the hardware design of ZigBee expansion board and the software implementation of transmission protocol stack and node,the hardware and software implementation of data processing based on ARM platform interface,and the design of data storage scheme in the whole monitoring system.(3)Based on GNSS/IMU combined positioning method,an improved Kalman filtering fusion positioning method is proposed.Environmental information is introduced into the fusion algorithm.By defining the sensor confidence region,the confidence level is calculated by the membership function,and the fusion weight coefficient is determined.In this thesis,the performance of GNSS/IMU positioning in bridge monitoring is analyzed by collecting actual bridge data and comparing the traditional fusion method with the improved method.The results show that the improved algorithm eliminates the problem of error divergence;when the satellite signal is affected,the number of visual satellites positioned in this thesis increases by 7 on average,the GDOP value decreases by 21.83%,and the positioning error decreases by 1.84 cm on average.(4)The design of monitoring platform is completed,and the connection between monitoring platform and monitoring system is achieved.The basic functions of monitoring platform are tested based on Runyang Bridge Deformation Monitoring Model.The results show that the monitoring platform can display the data of bridge monitoring system in real time and make visual analysis.It can provide remote data access and corresponding management for supervisors and users.