Research On Key Technologies Of Water Leakage Monitoring Prototype System Based On Optical Fiber Lateral Coupling Effect

Underwater submersibles require good watertightness during underwater navigation to prevent seawater from entering the submersible.However,they cannot truly simulate the underwater environment of the submersible in the design,so the airtightness detection during navigation It is very necessary.The internal structure of the underwater submersible is complicated,and there are many leaking points to be monitored,so the structure of the sensor should be simple and easy to install,and it needs certain flexibility.On the other hand,the sensor needs to be able to cope with a strong electromagnetic interference environment.The measurement method almost fails.In view of the above problems,a new type of water leakage sensor monitoring system is designed and designed,which has the characteristics of pertinence,high real-time performance and high resolution,and also has important practical significance.Based on the lateral coupling effect of optical fibers,the system uses the principle of water leakage to change the refractive index of the medium in the coupling region of the sensing probe,which causes a sudden change in the output light intensity.The system introduces in detail the sensor detection control module,the water leak location module,the weak light detection module,the signal acquisition and digital filter module,the STM32 main control module,the RS-422 transmission control module,and the user interface module in the water leakage monitoring system.The addressing and positioning method is used to complete the positioning of the leaking point.The addressing method is to use the main control chip to continuously issue the cyclic increment code,combined with the addressing circuit to control the work of the sensing probe;the function of the weak light detection module realizes the photoelectric conversion At the same time,the signal meets the standard of signal acquisition;because the optical signal is easy to introduce external interference,in order to prevent the misjudgment of the water leakage detection signal,and to reduce the difficulty of designing the analog circuit,the digital filter module is designed;the sensor is designed in a belt style,The measurement range of the sensor strip is 1m.The system cascades multiple sensor strips together to realize long-distance monitoring;adopts RS-422 bus and asynchronous communication method to turn down the data generated by each sensor strip one by one One is forwarded until the data enters the host computer;the user interface of the host computer intuitively reflects the status of each sensor probe of each sensor zone.By calibrating the state of no water leakage,the host computer converts the sensor data of water leakage into a Boolean indication.The coordinates of the Boolean element correspond to each sensing probe.By observing the status and coordinates of the Boolean element,the leakage state and the leakage point detected by the sensor are learned.The results show that the water leakage monitoring system can reach the measurement range> 6m,the positioning accuracy <5cm,the single point detection duration <25ms,the system cycle detection time <1s,and the missed and false detection rates ? 10%.Finally,the overall function of the designed water leakage monitoring system is tested.The performance of the water leakage monitoring system is stable and basically meets the design requirements.