Development Of 3D Ultrasonic Wind Speed And Direction Sensor Based On Time Difference Method

Three-dimensional wind speed and direction measurement has great value in agriculture,ecology and other fields,but the domestic three-dimensional ultrasonic wind speed and direction measurement technology still needs to be improved.The structure of 3D ultrasonic wind speed and direction sensor affects the ambient wind field to be measured,resulting in shadow effect and measurement error.Most of the existing shadow compensation methods are optimized from array structure or limited to two-dimensional wind speed and direction compensation.In order to solve these problems,a 3D ultrasonic wind speed and direction sensor based on time difference method is developed in this paper,and a 3D wind speed and direction shadow compensation method based on random forest regression algorithm is proposed.The main work of this paper includes:(1)Hardware design and firmware development of ultrasonic wind speed and direction based on time difference method.The measuring scheme of time difference method is adopted in the sensor design.Ultrasonic transducer with center frequency of 200 k Hz is selected as the transceiver probe.The horizontal arm length of three-dimensional orthogonal wind measurement structure is optimized.The optimized structure has high stability,moderate volume and low computational complexity of wind speed and direction data.The design uses STM32F407ZGT6 microprocessor as the core of the system,power management module,ultrasonic transducer driver module,signal processing module,channel selection module,high precision timing module,communication module and temperature measurement module are designed.The circuit performance of each module is good,and the excitation signal of the transducer is stable.After amplification and filtering,the ultrasonic echo signal gain reaches46 d B and the signal-to-noise ratio reaches 21 d B.The firmware works well under the task scheduling of the microprocessor,and the ultrasonic flight time is obtained and completed Calculation of wind speed and direction.(2)Shadow compensation method for 3D ultrasonic wind speed and direction sensor.The 3D wind speed and direction shadow compensation model was established by random forest regression algorithm.The fluid finite element software was used to obtain the wind speed and direction data affected by the sensor structure shadow effect,and the data was used to train the test model.The results show that the relative error between wind speed and theoretical value is reduced to less than ±1%,the average relative error between vertical wind direction and theoretical value is reduced to-0.08%,and the average relative error between horizontal wind direction and theoretical value is reduced to-0.8%,which verifies the feasibility and effectiveness of the random forest regression compensation algorithm in shadow compensation.(3)Performance test of wind speed and direction sensor system.C# language was used to complete the development of system test software,which supports serial port parameter setting,single and automatic collection,data display,visual curve and save and other functions,and supports the maximum data reading speed of 32 Hz.After the system delay of probe space distance and ultrasonic time of flight was corrected using the wind-free correction method,a comparison experiment was designed with other wind speed and direction measurement equipment,and the accuracy,stability,power consumption and other performance parameters were tested in the built experimental environment.The experimental results show that the wind speed measurement accuracy of the three-dimensional ultrasonic wind speed and direction sensor designed in this paper is within ±0.5m/s±0.05×v,and the wind direction measurement accuracy is within ±3°.Good system stability;Total power consumption as low as 960 m W.The research results of this paper can complete the high precision measurement of 3D wind speed and direction.The proposed 3D ultrasonic anemometer shadow compensation method can effectively reduce the influence of 3D shadow effect,and provide a low cost and high precision sensor for the future 3D wind speed and direction measurement.