Wind Speed Monitoring System In Forest Based On Optical Fiber Sensing Technology

Forest resources have become very important in the 21 st century,and the protection of forest resources has gradually become an important issue.The state has also put forward the concept of "lucid waters and lush mountains are invaluable assets".Forest wind speed monitoring is one of the important ways to protect forest resources.Forest wind is a double-edged sword for tree growth.It can not only help UAV spraying breeding,but also help the rapid spread of forest fire and affect forest meteorological observation.Therefore,forest wind speed monitoring has important practical significance.Optical fiber sensing technology has been widely used in information transmission and detection since its invention.This paper proposes a forest wind speed monitoring system based on optical fiber sensing technology,which includes the production and calibration of optical fiber sensor,the structural design and physical production of wind speed monitoring system,the design and experimental research of signal processing system and error analysis.Real time wind speed monitoring can be completed by transmitting and collecting wind speed information in real time through optical fiber.The specific research work of this paper revolves around the following points:The signal acquisition sensor selects the sensitized curvature optical fiber sensor,introduces the structure and sensing mechanism of the sensor,analyzes the characteristics of the sensitized curvature optical fiber sensor,selects the reasonable parameters of the sensitized curvature optical fiber sensor for the wind speed monitoring system,and processes the optical fiber sensor.The structure design of wind speed monitoring system is mainly divided into wind speed collection structure,force transmission structure,sensor interference structure and so on.The wind speed monitoring system introduces venturi tube to amplify the wind speed and improve the response of the monitoring system to the wind speed.At the same time,the mechanical structure of the monitoring system(such as wind wheel,ratchet,dowel pin and lever)converts the wind speed into the bending of cantilever beam.The mathematical model of the monitoring system is established,which shows that the bending frequency of the cantilever beam is directly proportional to the wind speed.At the same time,by fixing the sensitized curvature optical fiber sensor on the cantilever beam,the bending frequency of the cantilever beam can be output in real time through the optical fiber sensor,and then the wind speed can be calculated.The structure of the monitoring system is processed by 3D printing technology to complete the production of the overall structure.The optical fiber sensor signal processing system is designed to effectively process the weak signal output by the optical fiber sensor,and the wind speed can be measured by detecting the frequency of the periodic signal output by the optical fiber sensor.The light source modulation circuit,weak signal amplification circuit and band-pass filter circuit of optical fiber sensor are designed respectively,and the hardware circuit board is designed and manufactured.The wind speed monitoring system carries out wind direction test experiment and wind speed measurement experiment respectively.The wind speed measurement experiment is divided into indoor wind speed measurement and forest wind speed measurement.The wind direction experiment shows that the rotation starting wind speed is 0.5 m/s through different wind source positions and different wind speeds,which verifies that the wind speed monitoring system has effective wind direction.In order to illustrate the repeatability and stability of the monitoring system,each group of experiments is repeated three times under the same conditions.According to the calibrated optical fiber sensor,the indoor wind speed measurement error is within ±0.65 m/s,and the repetition accuracy is ±2.9%;The measurement error of forest wind speed is within ±0.63 m/s,and the repetition accuracy is ±2.7%.The error of indoor wind speed measurement and forest wind speed measurement is within ±0.02 m/s,which verifies the effectiveness of the wind speed monitoring system.