title: Development of an Unmanned Aerial Vehicle-Borne Crop-Growth Monitoring System.
abstract: In view of the demand for a low-cost, high-throughput method for the continuous acquisition of crop growth information, this study describes a crop-growth monitoring system which uses an unmanned aerial vehicle (UAV) as an operating platform. The system is capable of real-time online acquisition of various major indexes, e.g., the normalized difference vegetation index (NDVI) of the crop canopy, ratio vegetation index (RVI), leaf nitrogen accumulation (LNA), leaf area index (LAI), and leaf dry weight (LDW). By carrying out three-dimensional numerical simulations based on computational fluid dynamics, spatial distributions were obtained for the UAV down-wash flow fields on the surface of the crop canopy. Based on the flow-field characteristics and geometrical dimensions, a UAV-borne crop-growth sensor was designed. Our field experiments show that the monitoring system has good dynamic stability and measurement accuracy over the range of operating altitudes of the sensor. The linear fitting determination coefficients (R²) for the output RVI value with respect to LNA, LAI, and LDW are 0.63, 0.69, and 0.66, respectively, and the Root-mean-square errors (RMSEs) are 1.42, 1.02 and 3.09, respectively. The equivalent figures for the output NDVI value are 0.60, 0.65, and 0.62 (LNA, LAI, and LDW, respectively) and the RMSEs are 1.44, 1.01 and 3.01, respectively.
authors.affiliation: National Engineering and Technology Center for Agriculture/Jiangsu Key Laboratory for Information Agriculture/Collaborative Innovation Center for Modern Crop Production/Jiangsu Collaborative Innovation Center for the Technology and Application of Internet of Things, Nanjing Agriculture University, Nanjing 210095, China. nijun@njau.edu.cn.
authors.forename: Jun
authors.initials: J
authors.lastname: Ni
authors.affiliation: National Engineering and Technology Center for Agriculture/Jiangsu Key Laboratory for Information Agriculture/Collaborative Innovation Center for Modern Crop Production/Jiangsu Collaborative Innovation Center for the Technology and Application of Internet of Things, Nanjing Agriculture University, Nanjing 210095, China. 2015101038@njau.edu.cn.
authors.forename: Lili
authors.initials: L
authors.lastname: Yao
authors.affiliation: Nanjing Institute of Agricultural Mechanization of National Ministry of Agriculture, Nanjing 210014, China. zhangjc9@163.com.
authors.forename: Jingchao
authors.initials: J
authors.lastname: Zhang
authors.affiliation: National Engineering and Technology Center for Agriculture/Jiangsu Key Laboratory for Information Agriculture/Collaborative Innovation Center for Modern Crop Production/Jiangsu Collaborative Innovation Center for the Technology and Application of Internet of Things, Nanjing Agriculture University, Nanjing 210095, China. caow@njau.edu.cn.
authors.forename: Weixing
authors.initials: W
authors.lastname: Cao
authors.affiliation: National Engineering and Technology Center for Agriculture/Jiangsu Key Laboratory for Information Agriculture/Collaborative Innovation Center for Modern Crop Production/Jiangsu Collaborative Innovation Center for the Technology and Application of Internet of Things, Nanjing Agriculture University, Nanjing 210095, China. yanzhu@njau.edu.cn.
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: National Engineering and Technology Center for Agriculture/Jiangsu Key Laboratory for Information Agriculture/Collaborative Innovation Center for Modern Crop Production/Jiangsu Collaborative Innovation Center for the Technology and Application of Internet of Things, Nanjing Agriculture University, Nanjing 210095, China. 11114416@njau.edu.cn.
authors.forename: Xiuxiang
authors.initials: X
authors.lastname: Tai
mesh_terms: D000531:Altitude; D005740:Gases / Q000737:chemistry*; D009584:Nitrogen
chemical_list: D005740:Gases; D009584:Nitrogen
keywords: computational fluid dynamics; crop-growth model; field experiment; flow field analysis; monitoring system; unmanned aerial vehicle sensor