Uniform Spray Research Articles

Design and implementation of a nonlinear robust controller based on the disturbance observer for the active spray boom suspension

Spray boom vibrations are one of the main causes of the uneven distribution of agrochemicals. Using active suspension to maintain the correct height of nozzles is critical for obtaining a uniform spray pattern and minimizing the possibility of spray drift. However, the electro-hydraulic active pendulum boom suspension has nonlinear uncertain factors such as parameter uncertainties, external disturbances, model error, etc., which complicate the design of the controller. Therefore, this paper proposes a nonlinear robust feedback control method with disturbances compensation, which integrates a robust controller and disturbance observers through the backstepping method. Initially, to verify the performance of the controller, the Lyapunov stability theory is used to prove that the proposed controller can guarantee the given transient performance and the final tracking accuracy. Furthermore, taking the active suspension of a 28 m wide boom driven by a single-rod hydraulic actuator as an implementation case, the proposed NRCDC controller was compared with a variety of control schemes through a rapid control prototype of a pendulum active suspension. Finally, the proposed control scheme is implemented on a self-propelled sprayer with a boom of 12 m in length. The field test results show that all the performance indicators of the NRCDC controller are better than the other three conventional controllers. Both laboratory and field tests have verified the effectiveness and high performance of the proposed controller. Keywords: robust control, sprayer boom, boom suspension, hydraulic control system, disturbance observer DOI: 10.25165/j.ijabe.20231601.7007 Citation: Cui L F, Xue X Y, Kong W, Ding S M, Gu W, Le F X. Design and implementation of a nonlinear robust controller based on the disturbance observer for the active spray boom suspension. Int J Agric & Biol Eng, 2023; 16(1): 153–161.

Research on weed identification method in rice fields based on UAV remote sensing.

Rice is the world's most important food crop and is of great importance to ensure world food security. In the rice cultivation process, weeds are a key factor that affects rice production. Weeds in the field compete with rice for sunlight, water, nutrients, and other resources, thus affecting the quality and yield of rice. The chemical treatment of weeds in rice fields using herbicides suffers from the problem of sloppy herbicide application methods. In most cases, farmers do not consider the distribution of weeds in paddy fields, but use uniform doses for uniform spraying of the whole field. Excessive use of herbicides not only pollutes the environment and causes soil and water pollution, but also leaves residues of herbicides on the crop, affecting the quality of rice. In this study, we created a weed identification index based on UAV multispectral images and constructed the WDVI NIR vegetation index from the reflectance of three bands, RE, G, and NIR. WDVI NIR was compared with five traditional vegetation indices, NDVI, LCI, NDRE, and OSAVI, and the results showed that WDVI NIR was the most effective for weed identification and could clearly distinguish weeds from rice, water cotton, and soil. The weed identification method based on WDVI NIR was constructed, and the weed index identification results were subjected to small patch removal and clustering processing operations to produce weed identification vector results. The results of the weed identification vector were verified using the confusion matrix accuracy verification method and the results showed that the weed identification accuracy could reach 93.47%, and the Kappa coefficient was 0.859. This study provides a new method for weed identification in rice fields.

Stereoscopic plant-protection system integrating UAVs and autonomous ground sprayers for orchards.

For orchard plant protection, conventional large machines and small sprayers are practically restricted by either narrow planting intervals with dense leaves or their inadequate penetration power, which leads to an unsatisfactory effect of spray. This paper proposes a stereoscopic plant-protection strategy that integrates unmanned air and ground sprayers to spray different parts of canopies to improve uniformity. In order to verify the proposal, a stereoscopic plant-protection system (SPS) was developed, consisting of a small swing-arm sprayer and a T16 plant-protection Unmanned Aerial Vehicle (UAV). Then, optimal operation parameters were determined by Computational Fluid Dynamics (CFD) and orthogonal experiments, and the uniformity was finally quantified by trials. CFD and orthogonal experiments showed that a swing-arm angle of 60° and a forward speed of 0.4 m/s were optimal for the ground sprayer, whilst a height of 2.0 m from the top of canopies and a forward speed of 1.0 m/s were appropriate for the UAV. The trial results showed that the density of vertical droplet deposition varied from 90 to 107 deposits/cm2 in canopies, and the uniformity was 38.3% higher than conventional approaches. The uniformity of top, bottom, inside and outside canopies was significantly improved. Meanwhile, the density of droplet deposition on both sides of leaves in all test points exceeded 25 deposits/cm2, able to meet the standard of spray. This study provides a practical approach for uniform pesticide spray to large-canopy fruit trees. Moreover, the high flexibility of plant-protection UAVs and the significant trafficability of small swing-arm sprayers can solve the problem of large machine entering and leaving orchards.

Design and Experimental Verification of the YOLOV5 Model Implanted with a Transformer Module for Target-Oriented Spraying in Cabbage Farming

Due to large line spacing and planting distances, the adoption of continuous and uniform pesticide spraying in vegetable farming can lead to pesticide waste, thus increasing cost and environmental pollution. In this paper, by applying deep learning and online identification methods, control technology for target-oriented spraying is studied with cabbages as the research object. To overcome motion blur and low average precision under strong light conditions during the operation of sprayers, an innovative YOLOV5 model implanted with a transformer module is utilized to achieve accurate online identification for cabbage fields under complex environments. Based on this concept, a new target-oriented spray system is built on an NVIDIA Jetson Xavier NX. Indoor test results show that the average precision is 96.14% and the image processing time is 51.07 ms. When motion blur occurs, the average precision for the target is 90.31%. Then, in a field experiment, when the light intensity is within the range of 3.76–12.34 wlx, the advance opening distance is less than 3.51 cm, the delay closing distance is less than 2.05 cm, and the average identification error for the cabbage diameter is less than 1.45 cm. The experimental results indicate that changes in light intensity have no significant impact on the identification effect. The average precision is 98.65%, and the savings rate reaches 54.04%. In general, the target-oriented spray system designed in this study achieves the expected experimental results and can provide technical support for field target spraying.

Novel water penetration criterion for clay brick masonry claddings

• Investigated water absorption and water penetration in clay brick masonry. • Prepared masonry triplets with three different joint profiles for experiments. • Measure no water penetration till water content exceeds 90% of saturation capacity. Despite the impact of water penetration on the performance of building envelopes, no general agreement is available on implementing water penetration due to wind-driven rain (WDR) in hygrothermal and moisture safety analyses. This study proposes a novel criterion for water penetration in clay brick masonry that depends on the water content level of masonry. An experimental campaign investigating water penetration in clay brick masonry exposed to uniform water spray is conducted on masonry triplets prepared from bricks with different water absorption properties and three mortar joint profiles. During each test, water absorption and water penetration are registered continuously. The results show that no water penetration occurs unless the water content of the specimens is above 90% of their saturation capacity. The saturation level at which penetration starts is consistent across all joint profiles and brick types. Accordingly, exposure to driving rain at levels below the threshold may not lead to water penetration. The utility and implications of the proposed criterion are briefly demonstrated by analyzing water content and water penetration in a clay brick masonry façade. The resulting water penetration is compared with the results obtained using a commonly accepted reference model that assumes one percent of all wind-driven rain deposited on the façade to penetrate the clay brick cladding. By linking water penetration in clay brick masonry to the water content, the proposed criterion is an attempt to logically explain a phenomenon of high scientific and practical relevance for moisture analyses of a frequently used type of building envelope.

Deep learning-based early weed segmentation using motion blurred UAV images of sorghum fields

Weeds are undesired plants in agricultural fields that affect crop yield and quality by competing for nutrients, water, sunlight and space. For centuries, farmers have used several strategies and resources to remove weeds. The use of herbicide is still the most common control strategy. To reduce the amount of herbicide and impact caused by uniform spraying, site-specific weed management (SSWM) through variable rate herbicide application and mechanical weed control have long been recommended. To implement such precise strategies, accurate detection and classification of weeds in crop fields is a crucial first step. Due to the phenotypic similarity between some weeds and crops as well as changing weather conditions, it is challenging to design an automated system for general weed detection. For efficiency, unmanned aerial vehicles (UAV) are commonly used for image capturing. However, high wind pressure and different drone settings have a severe effect on the capturing quality, what potentially results in degraded images, e.g., due to motion blur. In this paper, we investigate the generalization capabilities of Deep Learning methods for early weed detection in sorghum fields under such challenging capturing conditions. For this purpose, we developed weed segmentation models using three different state-of-the-art Deep Learning architectures in combination with residual neural networks as feature extractors.We further publish a manually annotated and expert-curated UAV imagery dataset for weed detection in sorghum fields under challenging conditions. Our results show that our trained models generalize well regarding the detection of weeds, even for degraded captures due to motion blur. An UNet-like architecture with a ResNet-34 feature extractor achieved an F1-score of over 89% on a hold-out test-set. Further analysis indicate that the trained model performed well in predicting the general plant shape, while most misclassifications appeared at borders of the plants. Beyond that, our approach can detect intra-row weeds without additional information as well as partly occluded plants in contrast to existing research.All data, including the newly generated and annotated UAV imagery dataset, and code is publicly available on GitHub: https://github.com/grimmlab/UAVWeedSegmentation and Mendeley Data: https://doi.org/10.17632/4hh45vkp38.4.

Effect of aerial application of adjuvants on pepper defoliant droplet deposition and efficacy of defoliation sprayed by unmanned aerial vehicles.

Defoliant spraying is an important aspect of the mechanized processing of pepper harvesting. Complete and uniform spraying of defoliant could improve the quality of defoliation and reduce the impurity content in processing pepper. In this study, we assessed the effect of aerial spraying of adjuvants on physicochemical properties of defoliant solution and droplet deposition when using an unmanned aerial vehicle (UAV) for defoliation spraying. The results showed that Puliwang was a better aerial spray adjuvant suitable for spraying defoliants for processing pepper using UAVs, with a higher defoliation rate and better droplet deposition. Although the YS-20 adjuvant had a higher droplet deposition amount (0.72 μg/cm2) in the middle layer, its performance was poor in droplet size, density, and coverage. The size and density of the droplets added with the Manniu were basically the same as the Puliwang, even the distribution uniformity was better (the CV of the upper canopy layer was only 33.6%), but the coverage rate was poor. In the treatment with AS-901N, there was no marked increase in droplet size, so evaporation and drift were not improved, eventually resulting in a lower defoliation rate. Puliwang had the highest comprehensive score, followed by AS-910N, YS-20, and Manniu.

Optimal conditions and generation mechanism of jet atomization for uniform distribution of nano- and micro-droplets

This study provides a jet atomization technique to uniformly distribute nano- and micro-particles on the substrate by enclosing them in water droplets to avoid their aggregation. Jet atomization is a two-dimensional uniform spray and is generated using a diaphragm. The ideal jet atomization was achieved when the diaphragm was highly hydrophilic (contact angle 9.8°), and the spring constant was approximately 1.27 N m−1. The several experiments in this study supported the idea that jet atomization was caused by surface wave formed on the water film, rather than by boiling or cavitation of the water. The resonance between the diaphragm and the surface wave was investigated using a simple model. The results of this study can be expected to make fundamental contributions to pharmacy, medicine, and environmental science, where the uniform distribution of fine particles such as drugs, DNAs, and microplastics is required for the analyses of their properties.

Spray dried hydroxyapatite-based supraparticles with uniform and controllable size and morphology

This work aims to prepare uniform spray dried hydroxyapatite-based (SD HAP-based) supraparticles with controllable morphology via micro-fluidic spray drying. Sodium polyacrylate (PAAS) and sodium chloride (NaCl) were used to prepare the precursor suspensions by regulating the inter-particle repulsive forces and electrostatic shielding effect, respectively. The particle size (D50) and zeta potential of the suspension were highly associated with the mass ratio of HAP to PAAS (mH/mP) and the NaCl concentration (CNaCl), which further had significant effect on the permeability (k) of the droplet shell formed during spray drying and ultimately the supraparticle morphology. D50 ˂ 2 µm and absolute zeta potential ˃ 20 mV, obtained when mH/mP ˂ 100 under low CNaCl, rendered ultralow k and consequently deformed supraparticles; Whereas D50 ˃ 2 µm and absolute zeta potential ˂ 20 mV, achieved by decreasing PAAS amount, i.e. mH/mP ≥ 100 or improving CNaCl to efficiently screen surface net charge of HAP, high k and spherical supraparticles were thus preferentially formed.

Deposition of copper coatings on internal aluminum contact surfaces by high-energy plasma spraying

The deposition of functional coatings for various purposes on internal surfaces of devices and equipment is highly requested in a wide variety of production areas. In the electric power industry, there is a problem of combining a copper‑aluminum contact pair in the conical terminals of vacuum switches with the possibility of providing a low contact resistance and a high tightening torque or compression force, respectively. In this work, it is proposed to use high-energy plasma spraying for reliable combining copper and aluminum by Cu plasma spraying onto the inner conical Al contact surfaces. For this, a unique configuration of a high-energy plasma accelerator has been developed, which ensures producing and uniform spraying of Cu material in a single short-term working process (less than 1 ms). The dependence of the amount of deposited Cu material on the value of the specific supplied energy has been established to ensure the deposition of coating with a thickness not less than 40 μm and porosity from 3 to 8%. Also, the process implementation at increased supplied energy is found to provide the Cu and Al combination with a fourfold decrease in the contact resistance in comparison with the classical method of their connection. In addition, the high-energy plasma spraying results in forming an intermediate layer between copper coating and aluminum substrate containing intermetallic phases of Al4Cu6 and Cu3Al2. This layer is characterized by increased microhardness (up to 6–12 GPa) and provides high adhesion (more than 2000 MPa) due to hydrodynamic mixing of Cu and Al.

Metabarcoding of canopy arthropods reveals negative impacts of forestry insecticides on community structure across multiple taxa

Abstract Insecticides used to combat outbreaks of forest defoliators can adversely affect non‐target arthropods. Forestry insecticides typically suppress Lepidoptera larvae which are the cornerstone of the canopy community of deciduous oak forests. The abrupt removal of this dominant component of the food web could have far‐reaching implications for forest ecosystems, yet it is rarely investigated in practice owing to several methodological shortcomings. The taxonomic impediment and the biased nature of arthropod sampling techniques particularly impede the assessment of insecticide impacts on diverse communities. To tackle this issue, we propose an experimental approach combining sampling by pyrethrum knockdown and species determination via DNA metabarcoding, using community subsampling to derive estimates of species abundances. We applied this protocol to investigate the short‐term effects of the insecticides diflubenzuron (DFB) and Bacillus thuringiensis var. kurstaki (BTK) on canopy‐dwelling arthropod communities in German oak woodlands. Our approach allowed us to detect most of the diversity and integrate species abundances in our analyses. By classifying arthropod species into assemblages based on their expected sensitivity rather than coarse taxonomic groupings, we could unveil substantial effects of DFB across multiple taxa 5 weeks after application. Although strong effects on single species appear related to direct toxicity, substantial impacts of DFB on parasitoids and xylophagous beetles suggest that anti‐defoliator treatments can have previously unsuspected indirect effects on some components of forest arthropod communities. The impacts of BTK on community structure were consistent with that of DFB though much weaker. Synthesis and applications. Comparing diversity patterns in the arthropod communities of sprayed and unsprayed oak canopies, our results show that selective insecticides can alter species diversity in presumably non‐sensitive taxa. Even though the ecological significance of these impacts has yet to be assessed in an operational setting, their existence calls for increased regulatory scrutiny on indirect effects. As community approaches become more attainable with the rapid development of DNA metabarcoding, we suggest the inclusion of community‐level end points as regulatory requirements for the approval of forest‐use insecticides.

Herbicide Efficacy of Spot Spraying Systems in Fallow and Postharvest in the Pacific Northwest Dryland Wheat Production Region.

Real-time spot spraying technology has the potential to reduce herbicide costs and slow herbicide resistance. However, few studies exist on the efficacy of this technology in the Pacific Northwest (PNW). This research compared the herbicide efficacy (reduction in weed density and cover) of WEED-IT and WeedSeeker spot spraying systems to uniform spraying in fallow and postharvest in 2019 and 2020. Weed community types included naturally occurring weeds, natural + Russian thistle (Salsola tragus L.), or natural + kochia (Bassia scoparia (L.) A. J. Scott). Herbicides included glyphosate or the pre-mix bromoxynil + pyrasulfotole. Additionally, herbicide efficacy was studied with short stubble (~10 cm), tall stubble (~25 cm), and normal stubble (~20 cm) with chaff and straw removed. In fallow, herbicide efficacy was 1.5 times higher for uniform applications than for WEED-IT or WeedSeeker in 2019 and 2020. Herbicide efficacy was also 1.9 times higher for uniform applications in postharvest in 2019 but no differences were found in 2020. The weed community impacted herbicide efficacy but herbicide efficacy did not differ between residue management treatments. Finally, WEED-IT and WeedSeeker used 53% less herbicide volume in comparison to uniform applications. This research demonstrated that spot spraying technology can be efficacious and economical for growers in the PNW.

Hydraulic flip in a gasoline direct injection injector and its effect on injected spray

Hydraulic flip is a common phenomenon that occurs in a short injector nozzle with a contraction flow which results in a separation flow without a wall reattachment. This phenomenon usually occurs in a gasoline direct injection (GDI) injector because the nozzle’s length-to-diameter ratio is low with high injection pressure. The efforts to investigate the hydraulic flip in a fuel injector nozzle have been paid in several studies. However, the investigation on the phenomenon in an actual GDI injector has not been well clarified yet since it is complicated to be quantitatively investigated due to its microscale and the flow location inside a solid non-transparent material. Besides, the hydraulic flip also affects the near-nozzle spray characteristics, but the previous studies are insufficient to explain the whole mechanism and characteristic despite their importance on the engine combustion quality. In this study, the hydraulic flip characteristic is investigated by varying the hydraulic flip thickness. The nozzle with a thinner hydraulic flip resulted from the application of hydro-grinding machining on the nozzle inlet so it forms a nozzle with a round inlet edge and less flow contraction. The characterization of internal flow and its correlation with the injected spray was done by investigating the effect of hydraulic flip thickness. The hydraulic flip phenomenon and the injected spray were captured by a high-speed visualization using a synchrotron X-ray to obtain a phase-contrast image. As a result, the hydraulic flip phenomenon was observed clearly in the tested actual GDI injector nozzles. The hydraulic flip thickness difference and how it affects the spray characteristics, i.e., velocity distribution, flow coefficients, turbulence intensity, spray dispersion, and SMD, were clarified. The results show that the thinner hydraulic flip leads to a higher discharge coefficient, lower turbulence intensity which results in slightly worse atomization, and a slightly narrower spray angle with more uniform spray velocity distribution.

Evaluation of the Effect of Different Hand-Held Sprayer Types on a Greenhouse Pepper Crop

The cultivation of vegetables in greenhouses is characterised by high planting density and environmental conditions that favour the development of pests and diseases. These are mainly controlled using plant protection products applied with a hand-held sprayer. This is inefficient low-tech equipment that is difficult to calibrate. The study evaluates one hand-held spray gun and two hand-held spray lances that are widely used in greenhouse vegetable crops. The tests were carried out on a pepper crop at two different developmental stages. Plant canopy deposition and losses to the ground were quantified using a colorimetric method based on applying a tartrazine solution. The results show that the flat-fan spray lance obtains a more uniform spray distribution in the plant canopy and results in losses to the ground that are between 2 and 2.75 times less than when using the other hand-held sprayers tested.

Experimental investigation of water absorption and penetration in clay brick masonry under simulated uniform water spray exposure

In this study, we performed an experimental investigation of water absorption and penetration in clay brick masonry exposed to cyclic water spraying by employing a newly developed test setup. Several parameters, including brick absorption properties and different mortar joint profiles, were investigated. The specimens were exposed to a uniform water spray rate ranging between 1.7 and 3.8 l/m2/h, and water absorption and dampness patches on the non-exposed backside (the protected side) of the specimens monitored continuously. The results indicate that the amount of absorbed water is highly dependent on the water absorption coefficient and absorption capacity of the bricks, whereas the mortar joint profiles do not influence water absorption. The first dampness patches on the specimens' backside appeared in the vicinity of the head joint, and the time until the first patch appeared correlated well with water content levels. Accordingly, the first visible dampness patches appeared on the specimens' backside at water content levels corresponding to 50%–60% of full saturation level. Additionally, the specimens' backside reached 90% dampness at water content levels corresponding to 95% of full saturation level. As a feature attributed to the absence of known defects and zero differential air pressure, no measurable amounts of penetrated water could be collected at the specimens’ backside. The newly developed test setup might facilitate verification of moisture simulations and provide a basis for rational decision-making concerning clay brick masonry design and maintenance.

A novel approach to improve environmentally friendly machining processes using ultrasonic nozzle–minimum quantity lubrication system

In minimum quantity lubrication (MQL) machining, a small quantity of cutting fluid is air-atomized to generate fine liquid droplets, and they are injected into the machining zone. The effectiveness of the MQL system depends on the droplet size/distribution, spray shape, spray velocity, and area fraction covered by the droplets. In the present study, for the first time, a novel MQL nozzle has been designed and manufactured applying ultrasonic vibrations using piezoelectric discs tighten on the nozzle between the mechanical amplifying element and a support element. Ultrasonic vibrations can be used to effectively atomize the cutting fluid into fine and uniform-sized droplets and smaller spray angle with a larger spray deposition distance. Ultrasonic nozzle–minimum quantity lubrication (UN-MQL) system generates a mist-like uniform spray. The ultrasonic nozzle was designed and analyzed using the SolidWorks and Ansys Workbench software. Image processing techniques have been used to characterize the droplet sizes, and the droplet distribution after the oil has been sprayed onto a polished lead-coated plate by UN-MQL system as well as better understanding in the application of the ultrasonic nozzle for its effective use in practical industrial applications. A set of experiments have been conducted on AISI 304L stainless steel during turning with the developed setup, and the results have been compared with dry, wet, and conventional MQL turning processes. The fine droplets produced by the UN-MQL system penetrate effectively into the machining zone and consequently enhance the cooling-lubrication characteristic in the cutting zone. Spray angle of UN-MQL in comparison to conventional MQL systems decreased about 40% and 30% in air pressure of 6 and 3 bar, respectively. The rising inclination of the area fraction covered by droplets in variable air pressures has improved approximately 70% among the oil flow rates of 16 to 110 ml/h in the UN-MQL case as opposed to the conventional MQL system. The greatest quantity of decrement in mean droplet diameter which transpired in air pressure of 1 bar, reached nearly 63% for the oil flow rates of 16 ml/h, 30 ml/h, and 43 ml/h. Overall, the results obtained during UN-MQL turning experiments show that the surface roughness has been improved compared to dry, flood, and conventional MQL turning processes.

Design and evaluation of the target spray platform

The target-oriented spraying is an effective way to minimize chemical input in agricultural production and it is important to actualizing sustainable agriculture. This article focused on the design and optimization of the target spray platform. The spray platform consists of three parts: the vision system, the spray system, and the moving platform. All components were effectively connected and preliminarily evaluated especially regarding the response time and target spray accuracy. A simulation system was built considering the real crop geometric shape and nozzle spray pattern using the Monte Carlo method. The spray simulator was used to optimize the spray height objective function of spray deposition rate and coefficient of variance for the spray deposition. The spray process can be easily visualized and compared for different spray parameters. The indoor experiment setup was built to test and optimize the parameters of the overall system, which is flexible to verify the system. Afterward, the outdoor tractor-based equipment was designed to test the system for the field environment. The experimental result showed that 80% of the crop had a spray deviation from 0 mm to 28 mm and the proposed spraying system can reduce 46.8% usage of the chemical compared to the uniform spray method.

Additive manufacturing of magnesium alloy using uniform droplet spraying: modeling of microstructure evolution

In this study a material model is developed to predict the solidification microstructure of an additive-manufactured, fully dense magnesium (Mg) alloy using uniform droplet spraying (UDS). Specifically, the crystallite size distribution is simulated by a solidification model, consisting of a nucleation/fragmentation and a constrained growth description, calibrated via microstructural data from a single droplet splat. This is enabled by a semi-analytical thermal modeling framework, based on the superposition of moving Green’s and Rosenthal functions for the temperature field generated by a Gaussian source distribution. The model is implemented for layered ellipsoidal deposit sections on planar substrates by multi-pass spraying, and its predictions are validated against measured crystal sizes by image analysis of experimental micrographs of a Mg97ZnY2 alloy, to an error margin of ± 15%. The computationally efficient simulation provides insights to the deposit microstructure, and is intended as a process observer in a closed-loop, adaptive control scheme based on infrared temperature measurements.

Predicting spray deposit distribution within a cotton plant canopy based on canopy stratification porosity and Gaussian process models

To study the influence of foliage density and distribution on spray droplets distribution inside plant canopy, the optical porosity of vertically stratified layers of cotton canopy, was proposed to quantitatively depict the spatial distribution of cotton foliage. For calculating stratification porosity, a laser ranging bench was built to obtain ranging data for all the stratified layers. For acquiring droplet distribution data inside plant canopy, spray experiments were carried out by using artificial cotton plants as targets and water sensitive papers as a deposit sampling method. Using stratification porosities and droplets distribution data as training data, Gaussian process (GP)-based models were established to quantitatively identify droplet spatial distribution inside the canopy. The trained models predicted droplet distribution of the upper (UL) and middle layers (ML) with mean absolute percentage errors ( MAPE ) 0.0226, R 2 0.9309 and MAPE 0.0526 and R 2 0.9039, respectively. Prediction accuracy for the lower layer (LL) was MAPE 0.1181, R 2 0.3361. Furthermore, for droplet distributions of the different sections in the same layer, prediction accuracies for UL and ML were obtained with MAPE 0.2038, R 2 0.9114 and MAPE 0.3641, R 2 0.822, respectively. For prediction accuracy of the LL was MAPE 0.2468, R 2 0.4899. Considering the complex influence of all three foliage layers on droplets distribution of LL, and the horizontal velocity component of droplet movement, stratification porosity data could not explain droplets horizontal distribution in LL. Other description parameters should be included to improve model performance in future work. Moreover, the prediction model quantitatively revealed a uniform spray method could not produce a uniform deposition on the target, due to the interception of droplets by spatially inhomogeneous-distributed foliage. • GP-based prediction models of droplets distribution in cotton canopy built. • Stratification porosity used to depict foliage spatial distribution. • Models quantitatively reveal the influence of foliage on droplets distribution.

Development and Prototype Testing of an Agricultural Nozzle Clog Detection Device

HighlightsPrototypes of an agricultural nozzle clog detection system (for 18 nozzles) have been successfully developed.Spray quality characteristics (droplet size, pattern, and coverage) were not significantly affected when testing the device with extended-range nozzles (TeeJet XR8004).Most of the spray quality characteristics were significantly affected when testing the device with ultra low-drift nozzles (John Deere PSULDQ2004).Abstract. Agricultural nozzles are the main components that perform the spraying of agrochemicals, and their proper functionality is a key element for uniform spray application on crops. Because nozzles have small orifices, they can become clogged when there is debris from the agrochemical in the tank. Nozzle clogging during spray application results in poor pest and weed management and increased cost for re-spraying the affected crop row. Measures used to prevent nozzles from clogging include using screens or strainers to filter out debris before it reaches the nozzle tip, as well as performing regular checks on the nozzles. However, nozzle clogging still occurs during spraying despite the precautions taken. Thus, a device that can detect nozzle clogging during spraying is necessary to enable a quicker response that will ensure uniform application across each row of the crop. A novel, patented device for detecting clogged nozzles that is externally attachable to each nozzle on a sprayer boom was developed in the Precision Application Technology Lab at Arkansas State University. The main objective of this article is to present a general description of this prototype nozzle clog detection device and the nozzle clog detection system. Spray droplet size and pattern tests under controlled conditions and spray coverage tests under field conditions were conducted with and without the device to determine if there were significant differences in droplet size, spray pattern, or spray coverage between using and not using the device. The tests demonstrated that this new technology has potential for detecting clogged nozzles without significantly influencing spray quality for extended-range nozzles but not for ultra low-drift nozzles. To increase the reliability of the performance of this new technology, further improvements in the design need to be considered. Keywords: Clogged nozzle, Detection, Droplet size, Prototype device, Spray coverage, Spray pattern.