Development Of Beidou Distributed Deformation Monitoring System

Throughout the world,geological disasters cause huge losses every year,especially landslides,bridge and dam collapse,debris flow and other natural disasters,which pose a serious threat to the safety of people’s lives and property.At present,the carrier phase difference technology is mainly used in the field of deformation monitoring,and the related equipment derived from this technology is also widely used in other fields.Aiming at the problems of fixed monitoring mode,single positioning mode and poor flexibility of relevant differential equipment in the actual deformation monitoring,a Beidou distributed deformation monitoring system is developed in this paper.The main research results and innovations of this paper are as follows:(1)This paper describes the development and composition of global satellite navigation system,and analyzes the working principle of GNSS,including pseudo range observation equation and carrier phase observation equation,and discusses the classification of all errors in the positioning process according to the errors in the observation equation.The RTK difference technology commonly used in the field of deformation monitoring is introduced by single-difference and double-difference observation models,which provides a theoretical basis for the system design later.(2)Based on the concept of distributed,an innovative deformation monitoring method is proposed in this paper,including distributed main auxiliary positioning method and main auxiliary differential positioning algorithm.The distributed main and auxiliary positioning method is mainly to arrange the main monitoring stations in the micro area,and derive several auxiliary monitoring stations around to form the micro monitoring subsystem.The overall deformation of the micro area can be monitored by calculating the baseline length between the main and auxiliary monitoring stations.The main auxiliary differential positioning algorithm uses the pseudo range and carrier phase between the main and auxiliary monitoring stations to eliminate the error.The experimental results show that the accuracy can meet the monitoring requirements.(3)The distributed deformation monitoring system is designed,including hardware design,communication transmission design and related software design.In terms of hardware design,a low-cost receiver is independently designed based on stm32f767 core chip and UBLOX satellite receiving chip.The multi-module integration is realized by adding circuits such as multi-interface switching,which enhances the functionality of the receiver.In terms of communication transmission,different data communication transmission modes are designed according to the different actual monitoring environment,which improves the universality of the system.In terms of software design,the system designs the data solution software,which can solve the monitoring data of the main and auxiliary monitoring stations in real time.In addition,the deformation curve display software is designed based on Qt to realize the visual processing of deformation monitoring curve.Finally,the system is verified.Through the data analysis of the baseline solution results of two groups of different lengths of RTK point-monitoring and three groups of different lengths of main and auxiliary monitoring,it is concluded that the root mean square error of two groups of RTK baseline solution and three groups of main and auxiliary monitoring baseline solution are 3.43 mm,3.39 mm and 5.29 mm,5.49 mm and5.61 mm respectively.The results show that the distributed deformation monitoring system realizes the monitoring effect from "point" to "surface" in micro area,and the main and auxiliary differential positioning meets the monitoring requirements of the system.