基于IPv6和低功耗的混凝土测量系统的设计与实现

发布时间：2018-01-11 04:09

本文关键词：基于IPv6和低功耗的混凝土测量系统的设计与实现　出处：《山东大学》2017年硕士论文　论文类型：学位论文

【摘要】：钢筋混凝土在各种环境中都会受到不同程度的腐蚀,尤其是在富含有害离子的海水中,存在大量氯盐和硫酸盐,会分别跟钢筋和混凝土发生化学反应,造成钢筋腐蚀和混凝土胀裂。所以,对钢筋混凝土的腐蚀的检测在土木工程中有重要意义,可以为混凝土腐蚀的检测和防护提供参考。青岛跨海大桥于建设初期,在受到海水侵蚀的混凝土桥墩中预埋了大量传感器,可以测量其内部电化学参数。但是,传感器在桥墩上的位置及预埋的数量,给传统的现场测量带来很大困难,故对于青岛跨海大桥的这种复杂应用场景来说,需要利用其预埋的传感器实现简单有效的自动化测量,并通过无线的方式将采集到的数据传输到网络。在研究和对比了多种腐蚀电化学测量方法后,本课题采用交流阻抗法来测量和分析混凝土的内部特性,交流阻抗法是用小幅度正弦交流信号扰动电极,进行电化学测试的方法,根据测得的交流阻抗数据,来分析其电化学特性。为了能够简便且准确地测量混凝土的交流阻抗,本课题采用高精度的阻抗转换器系统解决方案AD5933,AD5933内部的DDS产生信号激励外部复阻抗,ADC采集响应信号,然后由片上DSP做DFT运算得到每个频率点上的复阻抗值。数据的上传则通过无线传感器网络,网络由网关、边缘路由器、协调器和节点组成。无线传感器网络的末端节点采集传感器数据,以无线方式进行通信,将数据上传到网关,由网关发布到互联网。综合考虑嵌入式硬件条件、网络协议和系统环境后,本课题以Contiki操作系统和CC2538控制器为基础,围绕低功耗和IP网络互联两大需求,将混凝土参数测量和无线传感器网络相结合,设计并实现了一个适用于青岛跨海大桥的混凝土检测系统。边缘路由其协调器和节点运行Contiki系统,无线传输采用IEEE 802.15.4协议标准,通过6LoWPAN实现IIEEE802.15.4和IPv6之间的适配,以uIPv6协议栈为基础,作适当的裁剪和必要的修改,形成一个更加轻量化的IPv6协议栈,并根据青岛跨海大桥的节点分布方式,设计与之适用的路由协议。系统网关采用运行OpenWRT的MT7688开发板,通过有线方式连接路由器实现与IP网络的连接,通过串口连接一个CC2538最小系统实现与无线传感器网络的桥接。在经过调试和改进后,本课题模拟青岛跨海大桥的现场环境,布置了四个无线传感器网络的子网,节点每隔6个小时采集一次数据,并上传到网关,由网关发布到互联网。经过一段时间的数据采集、统计和分析后,发现节点数据存在少量丢失的情况,但是并不影响长期的数据分析。本方案除了对青岛跨海大桥的腐蚀检测和防护有重要意义外,对公路、楼宇等土木建筑的混凝土检测也有一定的参考性。
[Abstract]:Reinforced concrete will be corroded in various environments, especially in the seawater rich in harmful ions, there are a lot of chloride and sulfate, which will react with reinforcement and concrete respectively. Therefore, the detection of corrosion of reinforced concrete is of great significance in civil engineering. Qingdao cross-sea bridge in the initial stage of construction in the sea erosion of concrete pier embedded in a large number of sensors can be measured its internal electrochemical parameters. The position of the sensor on the pier and the quantity of the preset bring great difficulties to the traditional field measurement, so it is very difficult for the complex application scene of Qingdao sea crossing bridge. It is necessary to use the embedded sensor to realize simple and effective automatic measurement, and to transmit the collected data to the network by wireless means. After studying and comparing many electrochemical corrosion measurement methods. In this paper, the AC impedance method is used to measure and analyze the internal characteristics of concrete. The AC impedance method is based on the measured AC impedance data. To analyze its electrochemical characteristics. In order to measure the AC impedance of concrete easily and accurately, a high precision impedance converter system solution, AD5933, is adopted in this paper. The internal DDS of AD5933 generates signals and excites external complex impedance to collect response signals. Then the complex impedance of each frequency point is obtained by the DFT operation of the on-chip DSP. The data is uploaded through the wireless sensor network, and the network is made up of the gateway and the edge router. The end node of wireless sensor network collects sensor data, communicates with wireless mode, uploads the data to the gateway, and publishes the data to the Internet by gateway. The embedded hardware condition is considered comprehensively. After the network protocol and system environment, this topic is based on the Contiki operating system and CC2538 controller, focusing on the two major requirements of low power consumption and IP network interconnection. Combining the measurement of concrete parameters with wireless sensor network, a concrete detection system suitable for Qingdao Bridge is designed and implemented. The Contiki system for edge routing and node running is designed and implemented. Wireless transmission adopts IEEE802.15.4 protocol standard, and adapts between IIEEE802.15.4 and IPv6 through 6LoWPAN. Based on the uIPv6 protocol stack, a lighter IPv6 protocol stack is formed with appropriate tailoring and necessary modifications, and the node distribution pattern of Qingdao Sea Crossing Bridge is adopted. The system gateway adopts the MT7688 development board running OpenWRT, and connects with IP network through wired router. A CC2538 minimum system is connected with the wireless sensor network through serial port. After debugging and improvement, this paper simulates the site environment of Qingdao sea crossing bridge. Four wireless sensor network subnets are arranged. The node collects data every six hours and uploads them to the gateway. After a period of time data acquisition, statistics and analysis are carried out by the gateway to the Internet. It is found that there is a little loss of node data, but it does not affect the long-term data analysis. This scheme has important significance for the corrosion detection and protection of Qingdao sea crossing bridge, as well as for highway. The concrete inspection of civil buildings such as buildings also has certain reference value.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP212.9;TN929.5;U446

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