Design And Implementation Of Ground Wind Field Measurement Equipment Based On Time Difference Method

In recent years,the application of UAV technology has developed rapidly.The Ministry of science and technology and the Ministry of agriculture have taken agricultural aviation application as an important supporting direction in the "12th Five-Year" scientific research plan.It has many advantages,such as fast operation speed,high efficiency,strong adaptability and good atomization effect.However,the distance between the UAV and the crop canopy is large,the speed of movement is high and the washing air flow is complex.The path planning,flight height and spraying dose of the current planting unmanned aerial vehicle(UAV)have great blindness,which not only affects the use efficiency of the liquid,but also makes it easy to cause unpredictable pesticide pollution.In field operation,the UAV is easy to be affected by meteorological conditions,and the droplet drift is serious,especially wind speed and wind direction.Therefore,the measurement of wind field information is very important in the research of droplet drift in UAV spraying.Based on this background,this thesis designs and develops two dimensional wind speed wind direction measuring instruments based on the Beijing natural fund project of the national agricultural intelligent equipment technology research center.The research method and design process of the ultrasonic wind measurement system based on the time difference method are elaborated in detail.First,the relevant background,research status and main contents of this paper are put forward,then the common methods and characteristics of wind speed measurement are studied,and the accuracy and application range of different wind measurement systems are compared,and the ultrasonic wind speed measurement system with MSP430 low power processor is determined.Secondly,build the hardware platform,take the MSP430 processor as the core,take the TDC1000 ultrasonic induction analog front end and the TDC7200 high precision time metering chip as the main hardware core,use the 200 KHz piezoelectric ceramic ultrasonic transducer,through the rational selection and improvement of the system power circuit,clock circuit,reset circuit,filter circuit And so on,so as to improve the timing accuracy.The software includes the program design of system initialization,data acquisition,wind speed calculation,data communication and so on.At the same time,the upper part of the computer is developed to collect the wind direction information of the PC terminal.After the completion of the design,the system experiment test is carried out.The experiment results show that the designed system meets the expected goals of the design,and has stable operation,good performance,low power consumption,low cost,etc.,and meets the test system requirements.The system design method can avoid excessive analog circuit design.Trouble,while ensuring high-precision picosecond time measurement.There are certain prospects and reference values in wind speed measurement,flow measurement and other applications.