Current status and future trends of precision agricultural aviation technologies

Modern technologies and information tools can be used to maximize agricultural aviation productivity allowing for precision application of agrochemical products.This paper reviews and summarizes the state-of-the-art in precision agricultural aviation technology highlighting remote sensing,aerial spraying and ground verification technologies.Further,the authors forecast the future of precision agricultural aviation technology with key development directions in precision agricultural aviation technologies,such as real-time image processing,variable-rate spraying,multi-sensor data fusion and RTK differential positioning,and other supporting technologies for UAV-based aerial spraying.This review is expected to provide references for peers by summarizing the history and achievements,and encourage further development of precision agricultural aviation technologies.

Research advances of the drift reducing technologies in application of agricultural aviation spraying

With the gradual deterioration of the ecological environment and the increase in requirements for the quality of modern life,the use of pesticides is bound to develop towards higher pesticide utilization and less environmental pollution,and the low-volume spraying for agricultural aviation operation combined with the Drift Reducing Technologies(DRTs)may be a useful way to achieve this goal.Based on an analysis of the spray drift mechanism and the primary factors influencing aerial spraying,previous research on DRTs in aerial spraying were reviewed and summarized,and it was found that DRTs in aerial spraying can effectively reduce the environmental pollution caused by pesticide drift by reducing the spraying amount of pesticides and improving the control effect of pesticides,included aerial electrostatic spray technology,aerial spray adjuvant,aerial air-assisted spray technology,drift reducing nozzles and aerial variable-rate spray technology.And according to the analysis of the current research status,some suggestions and countermeasures to reduce droplet drift of agricultural aviation spraying were put forward from the aspects of strengthening the research on DRTs for plant protection Unmanned Aerial Vehicle(UAV)and adopting reasonable DRTs methods.It is hoped that provide reference and guidance for the enterprises’product improvement and users’practical operation,and play the advantages of precision agricultural aviation spraying fully.

Review of tensairity and its applications in agricultural aviation

In recent years,the unmanned aerial vehicle(UAV)has undergone rapid development in field of agricultural plant protection;however,the payload and max-endurance are bottlenecks that limit its further development.Tensairity is a new structure consisting of a bag filled with low-pressure gas,an upper rigid rod and a lower flexible cable.It puts tension pressure on the whole structure through internal gas pressure,provides continuous support to the upper rigid rod,and that is to say,the tensairity improves the stability of the structure in some way.And also,tensairity is a self-supporting and self-balancing system,which means it is a simple,lightweight structure with small storage volume,strong bearing capacity,and low engineering cost.It also has the advantages of gasbag and BSS(beam string structure).The main objective of this research was to introduce the theoretical basis of tensairity and then discussed its development and applications.Moreover,the advantages and disadvantages of tensairity were summarized,and development prospects of tensairity in agricultural aviation were presented.At last,it can be concluded that tensairity has potentials in agricultural aviation.If tensairity is applied in agricultural UAVs,it will solve the two major problems of payload and max-endurance better,and help promoting the development of agricultural aviation technology in agricultural aviation administration and application.Also,it will help with meeting the aerial application requirements of high efficiency and maximal environmental protection.This research will provide a reference for improving working efficiency and economic benefits of UAVs in agricultural plant protection.

Development and prospect of unmanned aerial vehicle technologies for agricultural production management

Unmanned aerial vehicles have been developed and applied to support agricultural production management.Compared with piloted aircraft,an Unmanned Aerial Vehicle(UAV)can focus on small crop fields at lower flight altitudes than regular aircraft to perform site-specific farm management with higher precision.They can also“fill in the gap”in locations where fixed winged or rotary winged aircraft are not readily available.In agriculture,UAVs have primarily been developed and used for remote sensing and application of crop production and protection materials.Application of fertilizers and chemicals is frequently needed at specific times and locations for site-specific management.Routine monitoring of crop plant health is often required at very high resolution for accurate site-specific management as well.This paper presents an overview of research involving the development of UAV technology for agricultural production management.Technologies,systems and methods are examined and studied.The limitations of current UAVs for agricultural production management are discussed,as well as future needs and suggestions for development and application of the UAV technologies in agricultural production management.

A novel detection method of spray droplet distribution based on LIDARs

During the process of plant protection in agriculture,the distribution and deposition of droplets or fog fields could directly influence the effectiveness and efficiency of spray.The traditional method of measurement of the distribution of droplets mainly used water sensitive papers,glass containers or flour to collect data and inverse results,while a new method of measurement based on the principle of reflection of LIDAR was presented.Droplets were the major targets of the study,and four important algorithms were primarily developed,including the recognition and extraction of targets,the superposition in time-domain,the calculation of effective ranges of distribution,and the development of 3D distribution models.Combined with these algorithms,in order to eliminate the environmental noise,the methods of Fuzzy Environment Matching and Secondary Filter were created and utilized.Meanwhile,the statistics was used for analysis of the duration of scanning as well as computation of the distribution,with enough datasets but the minimum length of time.The results of the experiments showed that the relative error of measurement was less than 7%and Relative Standard Deviation was less than 16%,compared with the values of manual measurement.Furthermore,the 3D models were accurate and clarified in the wind-tunnel experiment.The completed system based on this method could adapt to the requirements of both indoor and outdoor detection.Besides,it is capable of the quantized detection of droplet distribution,providing an effective way of tests for spray technique,especially for the research of the application of plant protection by UAVs.

Test and evaluation method for endurance performance of electric multi-rotors spraying drones

The endurance performance(EP)of electric multi-rotors spraying drones(EMSDs)is a key technical indicator that ensures the completion of tasks and improves their usefulness.To improve the EP of current EMSD,a test system was designed to determine the EP based on the EMSD test platform,and the performance evaluation method was studied.Firstly,a test model was established to determine the equivalent energy dissipation using the performance-testing platform of the EMSD.Secondly,a multisensory test system was constructed.An attitude sensor,high-power DC power supply,infrared thermal imager,and serial port server were selected.The mounting fixture was designed to meet the universal mounting requirements of drone.In addition,the software LabVIEW was employed to program the code for the controller and the host computer,where functions such as data collection,data processing,communication,and graphical user interface(GUI),were performed reliably in real time.Thirdly,the test method was explored by considering factors such as the power consumption,thermal efficiency ratio,and unit load power consumption rate.In particular,a comprehensive index method and expert consultation weight method were used to evaluate the EP of the EMSD with multiple indexes.Finally,a systematic real-machine test was carried out on the three types of drones that are currently widely used in the market.The results verified the effectiveness and feasibility of the proposed method,which was employed to test and evaluate the EP based on the EMSD performance testing platform.At the same time,it can provide a reference for the development of the EMSD.

Vision-based adaptive variable rate spraying approach for unmanned aerial vehicles

The rapid developments of unmanned aerial vehicles(UAV)and vision sensor are contributing a great reformation in precision agriculture.Farmers can fly their UAV spraying pesticides around their crop fields while staying at their remote control room or any place that is separated from their farm land.However,there is a common phenomenon in rice planting management stage that some empty areas are randomly located in farmland.Therefore,a critical problem is that the waste of pesticides that occurs when spraying pesticides over rice fields with empty areas by using the common UAV,because it is difficult to control the flow accuracy based on the empty areas changing.To tackle this problem,a novel vision-based spraying system was proposed that can identify empty areas automatically while spraying a precise amount of pesticides on the target regions.By this approach,the image was preprocessed with the Lucy-Richardson algorithm,then the target area was split from the background with k-means and the feature parameters were extracted,finally the feature parameters were filtered out with a positive contribution which would serve as the input parameters of the support vector machine(SVM)to identify the target area.Also a fuzzy control model was analyzed and exerted to compensate the nonlinearity and hysteresis of the variable rate spraying system.Experimental results proved that the approach was applicable to reducing the amount of pesticides during UAV spraying,which can provide a reference for precision agriculture aviation in the future.