Research On Citrus Canopy Volume Measurement And Intelligent Target Spraying Technology For Nursery

Citrus is the fruit with the largest planting area and output in China,and precise production management of orchards can save costs,increase efficiency,improve quality,and increase yield.Canopy volume is one of the essential bases for the accurate management of orchards,such as pesticide,water,and fertilizer variable spraying and fruit tree yield estimation.Two-dimensional laser detection technology and oblique photography detection technology are common techniques to obtain the volume of the fruit tree canopy,However,the measurement will cause errors due to occlusion,scanning angle,and other factors,and the current measurement accuracy is usually evaluated by manual measurement.However,due to the fact that manual measurements use regular geometry to fit the canopy shape and are subjective,their accuracy cannot be guaranteed.Therefore,a new benchmark with less measurement error is needed to measure the accuracy and application potential of the detection technique.In addition,there are problems in citrus nurseries with different canopy biomass between rows and difficulty in precise spraying,and the plant protection spraying link still adopts artificial traction hoses and piggyback sprayers for excessive spraying,lacking efficient and intelligent mechanical equipment,and its labor intensity and low efficiency cause a lot of pesticide waste and environmental pollution.In view of the above problems,this study carried out research on citrus canopy volume measurement and nursery intelligent target spraying technology,and the main contents and conclusions are as follows:(1)Research on citrus canopy volume measurement technology.Taking Taroko blood orange fruit tree as the research object,four methods were used to collect the canopy volume of fruit trees by laser progressive scanning technology,manual measurement,two-dimensional laser measurement technology,and oblique photography technology.Through the combination of theoretical analysis and practical experiments,laser progressive scanning technology was established as a benchmark method for evaluating the accuracy of canopy volume,and the optimal volume calculation method was the slicing method.However,the manual measurement results are highly accidental and cannot be used as a benchmark to evaluate the accuracy of measurement technology,and the best volume calculation method is the accumulation addition of the round table and the coefficient of determination(R~2),root mean square error(RMSE)and mean relative error(MRE)are 0.633,2.733m~3 and 39.74%,respectively.Based on the results of laser progressive scanning technology,the canopy volume calculation method and accuracy of two-dimensional laser measurement technology and oblique photography technology were selected and evaluated.The experimental results showed that the oblique photography technique was more accurate,and the optimal volume calculation method was the slicing method,R~2,RMSE,and MRE were 0.979,0.205 m~3,and 2.81%,respectively.Followed by two-dimensional laser measurement technology,the best volume calculation method is the irregular triangular prism segmentation method,R~2,RMSE,and MRE are 0.968,0.698 m~3,and10.29%,respectively.At the same time,this study also discusses the application scenarios of two-dimensional laser detection technology and oblique photography detection technology.(2)Research on intelligent target spraying technology of nursery.Based on the two-dimensional laser sensor,the real-time detection technology of multi-box seedlings was studied,and the specific implementation process of real-time sensing technology of multi-box seedling canopy information was expounded.Aiming at this technology,a multi-channel nursery target sprayer was designed,the reliability of the critical components of the spray hardware system was verified,and the critical processes of each module of the control system were analyzed.Based on this,the prototype was trial-produced and integrated,and the functions of multi-channel seedling height adaptation and intelligent target spray of nozzles were realized.The results showed that the average absolute error value of the target accuracy of the sprayer was 3.53 cm,and the target error mainly came from the seedling target detection module.Increasing the spray pressure or turning on static electricity can reduce the droplet size and improve the droplet size uniformity with the same target height and implement speed.Taking the spray coverage and overall coefficient of variation of each part as the evaluation index,the optimal combination of spray parameters was 50 cm target height,0.5 m/s tool speed,and 0.25 MPa spray pressure under non-static conditions.Under electrostatic conditions,the optimal combination of spray parameters is a target height of 40 cm,implement speed of 0.5 m/s and spray pressure of 0.3 MPa.Under the optimal combination of spray parameters,the droplet coverage with and without static electricity and the sedimentation point density in the upper,middle,and lower frontal positions changed the same,and the density of sedimentation points at the canopy position was greater than 20/cm~2,which met the requirements of the general test method of industry-standard plant protection machinery.