Research On Detection For LAI Based On Ultrasonic Sensor

In agriculture,large number of pesticides are used for increasing income,excessive use of pesticides not only cause the waste of pesticides,but also make serious pollution to the environment,especially pesticide residues in food,poses a serious threat to human health.Targeting variable application is one of the key technologies to solve the problem,The aim of this paper is to study the technical problems of target variable application.First,use the ultrasonic sensor to realize the leaf detection under different leaf area index,Establishment the model relationship between leaf area index and echo energy,and then to provide technical basis for the guidance of spraying.The main research contents are divided into the following sections.(1)Leaf area index acquisition and design of detection system.According to the overall design requirements,set up indoor leaf area index detection test bed,the detection range of the ultrasonic sensor at different distances is obtained by the baffle method,obtain leaf area use the scanner and GIMP software,In order to obtain the leaves under different leaf area index,the leaves with different area were obtained by weighing method,and find out the average leaf weight coefficient,The leaves under different leaf area indices were weighed by electronic scales.The leaves are hung on the test bed by manual arrangement,The data acquisition and storage of ultrasonic sensor is realized by oscilloscope and computer software.(2)Introduction of ultrasonic sensor characteristics and extraction of ultrasonic echo characteristic information.Through the study of the ultrasonic sensor echo characteristics,it provides the basis for the data processing analysis of the sensor signal.(3)The influence of leaf area index and detection distance on ultrasonic echo signal was analyzed by single factor test,through the analysis of image and data variance test the results,and provide the data detection range for quadratic regression orthogonal test.(4)Design the test program of quadratic regression orthogonal and complete the detection of the entire test and signal acquisition,analysis and calculation results using MATLAB and other data processing software And established the relationship between the leaf area index and the strength of the ultrasonic signal,Verify the imbalance and regression significance of the equation.The correlation between the ultrasonic echo energy and the voltage value calculated by the model equation is obtained by the time domain energy calculation method,the results show that the calculated values of the model equations are significantly related to the actual values,So it is concluded that the model is universal,which can better reflect the leaf area under different leaf area index changes,And provide the control basis for the further the control of the target variable application.