Design Of Vibrating Wire Module System For Large-scale Monitoring Network

Slope safety monitoring of dams is one of the most important monitoring items during the construction period of large and medium-sized dams. In this paper, a monitoring system for the slope safety of dams based on vibrating wire sensors is developed. A kind of distributed field-bus data collection and communication method is used in this system to make a real-time monitoring on the macroscopic physical quantities of high slopes such as the dam seepage pressure, flow, deformation and so on. Through the human-machine interface, analysts can access to the dynamic indicators at any time and determine the state of the slope according to the collected data of the monitoring points.In this paper, we stand on a practical point of view of the construction of LAXIWA hydropower project, make a feasibility analysis and carry out the monitoring system design concepts and programs. And then, on basis of elaboration of the vibrating wire sensors'working principle and characteristics we give the mathematical models and theoretical calculation formula about the vibrating wire sensors,and in connection with the special working methods of this kind of sensor which must be excited after the pick-up, and whose output,the frequency signal is susceptible to interference, and it is very weak and vulnerable to be detected. To these questions,we give several specific solutions mainly from the following aspects.1.To keep C8081F040 microcontroller as the task, we design a vibrating wire sensor excitation circuit, a high-gain amplification circuit with filter detections,signal conditioning circuits and communications interface circuits, which make the bottom vibrating wire sensors reliablely excited and stabilely measured.2.A software which can decect vibrating wire sensors frequency is compiled in this paper, and the relevant parts of the communication interface software are designed. Furthermore,we relate these programs to some data processing, to ensure that the measurement is precise and stable;3.We focus on resolving the output signal's amplification and detection about the vibrating wire sensors,not only carry out a detailed error analysis,but also solving the interference from the rational design of hardware and software data-processing.4.We do make some relevant small-sized designs and improvements to make a prototype system on the basis of the above,and conduct a long-term stability experiment.Measurement results have shown that the monitoring system for the vibrating wire sensors has a very good measurement accuracy and resolution,and the system has a stable and reliable performance which well meet the design and application requirements.