| With the improvement in modernization,mechanization,and automation of China’s agriculture,smart agriculture has gradually replaced the traditional rough agricultural management and becomes a new theme in agricultural production.Implement of smart agriculture significantly improve the utilization rate of water and fertilizer in the field thus reduce the waste of resources,which facilitates high yield with high quality.Field water and fertilizer management of crops are important contents in precision agriculture,while real-time,non-destructive,and high-throughput acquisition of crop growth information is the prerequisite for precision crop production management.The development of spectral feature recognition technology and the application of intelligent platforms such as Unmanned Aerial Vehicles(UAVs),Unmanned Ground Vehicles(UGVs)in agricultural production has further enriched the high-efficient sensing methods of crop growth information.However,it does not take full advantage of combinative application of UAV and UGV due to the lacking of the crop growth information sensing methods and equipment of the combinative UAV and UGV in current researches.To solve these problem,this study constructed an air-ground integrated crop growth information acquisition system based on software and hardware engineering technology and crop canopy spectral monitoring mechanism.The UAV-borne crop growth information acquisition equipment was developed by analyzing the spatial distribution characteristics and geometric size of the downwash flow field of multi-rotor UAV on crop canopy surface.The UGV-mounted crop growth monitoring equipment was developed by analyzing the phenotyping structure change characteristics during the whole growth period and cultivation row spacing requirements of different wheat varieties.Combined with the operating conditions under the interference of the road surface in the field,the kinematics model,fuzzy PID speed control model,and inertial navigation method of the wheeled UGV were constructed.In order to realize the combination of air-ground nodes,based on the virtual instrument architecture,an air-ground integrated crop growth monitoring system is developed using Lab VIEW development environment,with air-ground nodes management functions.In addition,the spectral monitoring model of wheat growth information was constructed through wheat plot experiments,which can realize the accurate acquisition of wheat growth information.The results provide a new idea for applying UAV and UGV nodes in crop growth monitoring,fill the gap in this research field and provide theoretical basis and technical support for promoting crop growth information acquisition technology in China.Firstly,the UAV-borne lightweight multispectral crop growth information acquisition sensor is designed according to the upper payload limit of the small quadrotor UAV in this research.The standard test height of the sensor is 1 m,the test field angle is 27°,and the weight is only 11.34 g.Meantime,through the three-dimensional(3D)modeling of UAV and CFD(Computational Fluid Dynamics)numerical simulation,the distribution range of the downwash airflow field is simulated and analyzed.Nine 3D airflow field testers are used to test the actual distribution range of the downwash airflow field of UAV.The results show that when the UAV hovers 1 m from the crop canopy,the shape of the airflow field generated on the crop canopy surface is elliptical,the length of the long half axis is about0.45 m,and the short half axis is about 0.4 m.According to the size of the sensor test field,the influence range of the airflow field,the installation position of the sensor was determined.Then,a sensor support was designed to equip the crop growth information acquisition sensor.This research provides a systematic design scheme and practical equipment for UAV low-altitude tests equipped with the crop growth information acquisition sensor.Secondly,according to the characteristics of wheat crop agronomic cultivation,the characteristics of farmland road obstacles,and the near-ground test requirements of the active and passive light source crop growth information acquisition sensors,a wheeled UGV structure with high ground clearance and adjustable wheel spacing was designed.3D model of the robot is constructed using Pro / E software,and the road obstacle models such as pits and bumps of fields are constructed by Adams software.Then the operation stability is simulated and analyzed,and the simulation results show that the vibration of the center of mass of the UGV is less than 0.2 cm when the road is smooth,and the maximum vibration of the center of mass of the wheeled UGV is 1.78 cm in the process of obstacle crossing(10cm pits and bulges).On basis of the simulation results,the wheeled UGV is processed and tested.The results show that the robot has no vibration at the center of mass when running on a flat road.When running on the field road,the maximum vibration of the center of mass is 1.51 cm,only 1.3 % of the body height.Furthermore,based on the motion model of wheeled UGV with differential steering,the kinematics model and inertial navigation model under the interference of farmland road factors are established.Through the actual measurement of straw coverage,soil moisture content,compactness,and the running speed of wheeled UGV,a fuzzy PID speed control model of the in-wheel motor was constructed,and the effectiveness of the speed control model was verified by Matlab.The fuzzy PID speed control model,motion model,and inertial navigation method are further combined and tested.The test show that this method can effectively improve the motion and navigation accuracy of wheeled UGV.Then,the test advantages of the air-ground platform are analyzed based on the research and development of UAV-borne crop growth information acquisition equipment and wheeled UGV-borne crop growth information acquisition equipment.According to the test mode and operation characteristics of the two platforms,the quick and comprehensive obtain of the crop growth information of cropland by the UAV locate the representative even and uneven crop growth areas.According to the positioning information of the UAV,the wheeled UGV travels to a representative test area for the accurate,efficient,and high-throughput acquisition of crop growth information.In order to realize the efficient management and control of air-ground node data,the networking method and the combined application method of the crop growth information acquisition equipment in the air-ground integration are studied.A digital crop growth information acquisition system based on Lab VIEW virtual instrument architecture is constructed with the Internet of Things technology(Io T)as the link.The system has the functions of motion control for ground wheeled UGV node,acquisition and control of sensors carried by air-ground nodes,and management and combination analysis of test data.Cooperative test of air-ground nodes shows that the use of UAV node can better distinguish the uniformity of wheat growth,and the use of wheeled UGV node can effectively improve the accuracy of the test results.This study provides new points,methods,and equipment for the subsequent research on the integrated air-ground platforms. |
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