【作者】 杨浩；

【导师】 姜德生；

【作者基本信息】 武汉理工大学 ， 检测技术与自动化装置， 2008， 硕士

【摘要】 长期以来,由于技术水平的限制,对桥梁进行索力监测时经常采用频率法,其中的数据采集部分经常采用压电陶瓷加速度传感器。这种方法具有检测速度快、测量精度高的优点。但是由于压电陶瓷加速度传感器输出的是弱电信号,要实现远距离传输,需要在电路中加入许多放大器,从成本和施工考虑,这种方法很难实现索力远程实时监测,只适用于索力的定期检测。同时,在某些情况下,这种方法的低频特性也不是很好。随着光纤传感技术的发展,国内外提出了基于光纤光栅传感器的桥梁索力监测系统,它能够克服传统的检测技术的上述缺点,低频特性好,并且可以很方便的实现索力远程实时监测,具有一系列的优势。但同时带来了新问题:由于桥梁拉索数量很多,出于成本以及施工条件的考虑,不可能在每根拉索上安装光纤光栅传感器,只能将传感器固定在某几根拉索上,当需要测量其他拉索受力情况时,传感器的拆卸安装也需要耗费大量的人力物力。针对这种情况,本文提出了一种基于光纤光栅的桥梁索力无线检测系统。由于在数据的发送端和接收端采用了移动方便的无线传输模块,在需要测量桥梁其他拉索受力情况时,该系统能够在很大程度上减小传感器及相关光缆电缆的拆卸安装所耗费的大量人力物力,很好的克服了上述系统的缺点,并且同时具备很多优点,如灵敏度高、耐腐蚀、电绝缘、传输距离远等,而且结构简单、尺寸小、质量轻、频带宽、可进行温度、应变、压力等多种参数的分布式测量,具有很强的工程意义。本系统由数据采集、数据无线传输和监测评估三部份组成。系统利用光纤光栅传感器实现对桥梁索力的实时数据监测;采用无线传输模块实现数据的无线传输;利用虚拟仪器在上位机实现监测与健康评估。数据采集部分负责收集传感器传输的光信号,经波长解调后通过串口发送给无线发送模块;数据无线传输部分包括无线发送模块和无线接收模块,由发送模块将下位机送来的索力监测数据按照特定传输协议发送给接收模块;监测评估部分包括串口通讯部分和数据分析部分,由相应的监测评估软件实现数据的处理,图表显示和分析。本文主要论述了光纤光栅应变传感器,光纤光栅温度传感器和光纤光栅测力环的工作原理及具体实现,探讨了无线传输模块nRF24E1的工作原理,并且分别利用C语言和LabVIEW设计了无线传输部分软件系统和客户端数据处理部分软件系统,实现了监测数据的分类管理,历史查询和图表显示。更多还原

【Abstract】 For a long time, because of the limitation of technology, in the health monitoring system of bridges’ cables, people usually use piezoelectric ceramic acceleration sensors to measure stress from cables. This method has advantages such as fast detection speed and high precision. However, because the output signal of sensor is weak electric signal, in order to achieve long-distance transmission, we need to add multi-level circuit amplifiers. Considering the cost and construction conditions, this method is hard to achieve real-time remote monitoring of the cable, only applies to the regular cable force detection. At the same time, in some cases, the low-frequency characteristic of this method is not very good.With the development of optical sensing technology, at home and abroad many people propose the bridge cable force monitoring system based on FBG sensors. It can overcome the shortcomings of the traditional detection system with a range of advantages. But it also brought a new problem: With the large number of bridge’s cables, considering the construction costs and the working conditions, it can not install FBG sensors on each cable, and sensors can only be fixed in some cables. When we need to measure other cable force, we will waste a significant amount of manpower and resources.In view of this kind of situation, this article designed one wireless monitoring system based on FBG for the detection of the tension of bridge’s cables. Using the wireless transmission, this system can overcome the shortcomings of the system mentioned above, and it also has lots of advantages, such as high sensitivity, corrosion, electrical insulation, long transmission distance, explosion resistance, anti-electromagnetic interference, etc. It also has simple structure, small size, light weight and broad band. And it can be used in many kinds of distributed measurement for temper, stress and strain. and has very strong significance in the project.Associated with the project, the research on monitoring automation and safety evaluation of bridge cable tension is investigated in this paper. In this project, we use optic fiber sensors to measure stress from cable, then we use wireless transmission module to transfer data from bridge scene to control center, in control center we use Virtual Instrument design the software system to monitor and evaluate the cables’ situation of the bridge. This system consists of three parts: data acquisition, data wireless transmission and data processing. The first part is a distributed system consists with optic fiber sensor. This part is designed to gather the optical signals which are sent out by the FBG sensors, then the signals are sent to wireless transmitter module after the wavelengths of the signals are demodulated. The second part consists of wireless transmitter module and wireless receive module. In this part, the transmitter module transmits the signals of the cables in certain transport protocol and the receive module receives the signals. The third part consists of serial communication system and analysis system. This part processes the data and gives a final conclusion.In this paper we mainly discuss the working principle of Fiber Bragg Grating Strain Sensor, Fiber Bragg Grating Temper Sensor, FBG Load Cell and the wireless transmission module nRF24El. Then we design the wireless transmission software system with C language and data processing software system with LabVIEW. And with the help of the system, we can manage the data effectively, and look the historical and present data through charts, graphs and excel documents.更多还原