Experimental Study On Microwave Doppler Speed Sensor For Agricultural Machiner

When the tractor is working in the field,the speed information is the important information of the tractor.Because of the complicated working conditions of the tractor,it is difficult to obtain the speed information of the tractor accurately.At present,although some tractors in China are equipped with speed display instruments,they basically get signals through the speed sensor of the transmission shaft,and some advanced tractors abroad have adopted radar,GNSS and other equipment to measure the speed.Measuring the actual running speed of tractors is very important for controlling the use of expensive pesticides,fertilizers and seeds.At present,the main means of speed measurement in China are GNSS and ground wheel speed measurement.GNSS needs difference to ensure high accuracy,but the price is high and the signal accuracy is not high in rainy days.Due to the working environment of tractors,there is a slip rate of ground wheels.Therefore,Doppler radar based on microwave technology is studied and designed,which has good penetration,stable signal input and output and is not affected by weather environment.Based on USB 3200 Altai acquisition card,the FFT algorithm is studied.Taking Mather Ferguson 1204 tractor as the test object,collected and processed data using data collection card,and confirmed the feasibility of the speed measurement system through experiments.Under the conditions that the average tractor speed is 3.05 km/h,5.18 km/h and7.11 km/h.The absolute error is 0.29 km/h and the maximum relative error is 3.14%.Testing has shown that it meets the basic needs of agricultural technology.According to Doppler radar effect and its related parameters the velocity measurement accuracy of radar sensor is experimentally studied.The specific research work is as follows:1.Research and analyze the principle of agricultural machinery microwave Doppler speed radar sensor speed measurement and provide the necessary theoretical basis for the parameter setting of microwave Doppler sensor in agricultural speed measurement.2.Through the study of FFT algorithm,the road speed test is carried out,the working principle structure diagram of speed radar sensor and DFT and FFT algorithms for realizing frequency spectrum analysis are analyzed,the signal processing methods are compared,the algorithm used is determined,and the agricultural machinery microwave Doppler radar speed measurement system based on VB 6.0 is designed according to the needs and functions of FFT algorithm.3.The field experiment,based on Visual-Basic 6.0,designed the agricultural machinery speed measuring system with microwave Doppler effect,including lower computer,vehicle terminal,upper computer,data processing,display frequency and so on.The computer can display frequency data,data record query and parameters.