Single-Neuron PID UAV Variable Fertilizer Application Control System Based on a Weighted Coefficient Learning Correction

Abstract

Agricultural unmanned aerial vehicles (UAVs), which are a new type of fertilizer application technology, have been rapidly developed internationally. This study combines the agronomic characteristics of rice fertilization with weighted coefficient learning-modified single-neuron adaptive proportional–integral–differential (PID) control technology to study and design an aerial real-time variable fertilizer application control system that is suitable for rice field operations in northern China. The nitrogen deficiency at the target plot is obtained from a map based on a fertilizer prescription map, and the amount of fertilizer is calculated by a variable fertilizer application algorithm. The advantages and disadvantages of the two control algorithms are analyzed by a MATLAB simulation in an indoor test, which is integrated into the spreading system to test the effect of actual spreading. A three-factor, three-level orthogonal test of fertilizer-spreading performance is designed for an outdoor test, and the coefficient of variation of particle distribution Cv (a) as well as the relative error of fertilizer application λ (b) are the evaluation indices. The spreading performance of the spreading system is the best and can effectively achieve accurate variable fertilizer application when the baffle opening is 4%, spreading disc speed is 600 r/min, and flight height is 2 m, with a and b of evaluation indexes of 11.98% and 7.02%, respectively. The control error of the spreading volume is 7.30%, and the monitoring error of the speed measurement module is less than 30 r/min. The results show that the centrifugal variable fertilizer spreader improves the uniformity of fertilizer spreading and the accuracy of fertilizer application, which enhances the spreading performance of the centrifugal variable fertilizer spreader.

Droplet Deposition of Leaf Fertilizers Applied by an Unmanned Aerial Vehicle in Coffea Canephora Plants

“…These differences can be attributed to the architecture of the canopy of plants after the harvest pruning and distance between plants in the planting rows; plants closer to each other avoid the slide of the solution to the soil and contribute to a better penetration of the sprayed droplets. The effect of the centrifugal nozzle rotations on the deposition and uniformity of droplets was found in other studies [13][14][15], as well as the effect of heights of flight [12,24,25].…”

“…The mean coefficient of variation increased when the height of flight and rotation was increased to 10,000 rpm and decreased when the height of flight was decreased to 2.0 m. These differences in coefficients of variation can be due to the lack of obstacles between the nozzles and upper canopy layer. In addition to height of flight and centrifugal nozzle rotation, the downwash effect of the UAV generated by the UAV rotors and structure may have had a significant effect on the distribution and uniformity of droplets [12,14,15].…”

“…In addition to these factors, those related to the quality of spraying and application of leaf fertilizers should be considered, including the choice of fertilizers that have high dilution capacity in the mixture, and operational factors for the UAV calibration and adjusts, these factors were evident in treatments T1 and T2. Therefore, the height of flight and centrifugal nozzle rotations are important, but in addition to these factors, flight speed and the flow of the nozzles are important variables that define the quality of deposition and absorption of leaf fertilizers [12].…”

“…These studies determined the effects of application rates, flow of spray tips, speed, operational height of flight, and planning flight pathways [9][10][11]. However, these studies were specific, considering the application of agrochemicals, and investigations on the use of UAVs for the application of leaf fertilizers are scarce and limited to studies on application efficacy [12], disregarding the efficacy of the adherence and absorption of the nutrients applied. Leaf fertilizers have characteristics connected to the solution mixture in the UAV application tank that affect the spraying efficacy and, consequently, the efficacy of retention of absorption of fertilizers, for example, the density, viscosity, and surface tension of the solution.…”

Simulation Analysis and Test of Gap Squeeze Gear Type Fertilizer Discharger for Granular Fertilizer Containing Caking

“…In order to verify the feasibility of the simulation above method and the correctness of the optimization results, a bench test of the gap squeeze gear type and gap squeeze gear type fertilizer discharger fer conducted [38,39]. The test rig is an independently designed fertilizer discharge test rig, and the trial was completed in September 2022 at the Intelligent Agricultural Equipment Engineering Laboratory of Harbin Cambridge College.…”