| The accurate acquisition of wind speed and direction data among the meteorological elements on the ground plays an important role in weather forecasting,disaster prevention and mitigation,scientific research and other fields.Wind speed and direction data are generally obtained by wind measurement sensors,and the existing wind measurement sensors are mainly mechanical,thermal,Pitot tube,ultrasonic,silicon piezoresistive,etc.These sensors have met the basic requirements for the operational application of meteorological observation.With the development of meteorological observation needs,the observation of wind has put forward a new demand for refinement and globalization,and the need to achieve real-time observation of wind speed and direction in extremely low temperature(down to-55 ℃)areas such as the North and South Poles.Since the extremely low temperature will have an impact on the performance of the sensitive elements of wind sensors,it is difficult for the existing wind sensors to adapt to such extremely low temperature environments.This thesis takes ultrasonic wind measurement sensor as the research object,and studies and designs its transducer working environment,signal processing hardware system and software system.The main work of the thesis is as follows:(1)Analyze and study the current situation of wind measurement sensors at home and abroad,propose a method to provide constant temperature protection for sensitive components,and use the technology of combining fuzzy PID constant temperature control with traditional ultrasonic wind measurement sensors to develop a wind speed and wind direction sensor measurement and control system based on the principle of time-difference method ultrasonic wind measurement in extremely low temperature environment.Based on the selection of the transducer performance and technical indicators to meet the demand,the study of temperature changes on the impact of conventional transducer index parameters,the design of the transducer thermostat protection device to ensure the best working condition while preventing the normal transmission and receipt of ultrasonic signals covered by snow and ice.(2)According to the ultrasonic signal frequency range,electrical signal characteristics,the system stability in very low temperature environment as the goal,the design of the hardware circuit system,the STM32 microcontroller as the system controller,the design of the transducer driver circuit,amplifier circuit,second-order filter circuit and voltage comparison circuit,and through the circuit simulation software to verify the rationality of the design circuit.(3)In order to control the constant working temperature of the transducer and ensure the normal transmission and reception of ultrasonic waves,the software system is designed.On the basis of wind speed and wind direction measurement and calculation,the temperature control algorithm program is designed,and the temperature control of the transducer is realized by fuzzy PID,and the RS485 serial communication module based on Modbus protocol is designed.(4)The data calibration of the transducer was carried out using wind tunnel test,and its accuracy was analyzed by error to see if it meets the design standard of conventional wind measurement transducer.To further verify the working performance of the sensor in the low temperature environment,the sensor is installed in the same natural low temperature environment with the same type of wind measurement sensor after calibration,and the relative error of the measurement data is compared,and finally the sensor is simulated in a low temperature chamber to simulate the very low temperature environment for the environmental adaptation simulation test. |
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