Preliminary evaluation of a blast sprayer controlled by pulse width modulated nozzles

[EN] Precision spraying relies on the response of the spraying equipment to the features of the targeted canopy. PWM technology manages the flow rate using a set of electronically actuated solenoid valves to regulate flow rate at the nozzle level. Previous studies have found that PWM systems may deliver incorrect flow rates. The objective of the present study was to characterize the performance of a commercial blast sprayer modified with pulse-width-modulated nozzles under laboratory conditions, as a preliminary step before its further field validation. Four different duty cycles (25 percent, 50 percent, 75 percent and 100 percent) and four different pressures (400 kPa, 500 kPa, 600 kPa and 700 kPa) were combined to experimentally measure the flow rate of each nozzle. Results showed that the PWM nozzles mounted in the commercial blast sprayer, under static conditions, were capable of modulating flow rate according to the duty cycle. However, the reduction of flow rates for the tested duty cycles according to pressure was lower than the percentage expected. A good linear relation was found between the pressure registered by the control system feedback sensor and the pressure measured by a reference conventional manometer located after the pump. High-speed video recordings confirmed the accurate opening and closing of the nozzles according to the duty cycle; however, substantial pressure variations were found at nozzle level. Further research to establish the general suitability of PWM systems for regulating nozzle flow rates in blast sprayers without modifying the system pressure still remains to be addressed.This research was funded by the Government of Spain through the project "Smart spraying for a sustainable vineyard and olive trees" PIVOS (PID2019-104289RB).Ortí García, E.; Cuenca, A.; Pérez Teruel, M.; Torregrosa, A.; Ortiz Sánchez, MC.; Rovira Más, F. (2022). Preliminary evaluation of a blast sprayer controlled by pulse width modulated nozzles. Sensors. 22(13):1-12. https://doi.org/10.3390/s22134924112221

Design, construction and testing of an apricot tractor-trailed harvester

[ENG]The purpose of this research is to facilitate the mechanical harvesting of apricots (Prunus armeniaca L.) for industry. A tractor-trailed harvester was built to catch the fruits detached from apricot (cv. Búlida) trees by vibratory systems. This machine is a low profile catcher that can move under the trees in high-density canopies where umbrella-type harvesters cannot. The trailer is able to work under trees with as little free-trunk height as 0.35 m. The tests were done in 5- to 9-year-old apricot trees, planted in two frame, 2.5 m and 4.5 m in-the-row distances, with 6.5 m between rows in both cases. To detach the fruit, two hand-held pneumatic shakers were used. Harvest rate was 61 and 44 trees h-1 for each type of orchard, respectively. The main conclusion is that the trailer, together with branch-shakers, can work in narrow orchards of low canopy trees where other machines can not go in. [ESP] El objetivo de este trabajo fue facilitar la recolección mecanizada de albaricoques (Prunus armeniaca L.) para industria. Se ha construido un remolque recolector arrastrado por tractor para recoger los albaricoques cv. Búlida derribados de los árboles mediante sistemas vibratorios. El remolque puede trabajar a muy poca altura sobre el nivel del suelo, con lo que puede moverse bajo los árboles en plantaciones de alta densidad, en las que las cosechadoras basadas en paraguas invertidos no pueden actuar. Además, el remolque se puede adaptar a árboles con alturas de tronco tan reducidas como 0,35 m. Los ensayos se llevaron a cabo en albaricoqueros de 5 a 9 años de edad y plantados en marcos de 2,5 y 4,5 m entre árboles de la fila y 6,5 m entre filas. El derribo de los frutos se realizó con vibradores neumáticos. La capacidad de trabajo del equipo fue de 61 y 44 árboles h-1 para cada distancia de plantación, respectivamente. La principal conclusión es que el remolque, conjuntamente con vibradores de ramas, puede trabajar en plantaciones de marco estrecho y árboles con la cruz del tronco baja donde otras máquinas no pueden actuar.The authors would like to thank the Spanish Ministerio de Ciencia y Tecnología for supporting the AGL2001-3075 project, the Region of Murcia’s Consejería de Agricultura, Agua y Medio Ambiente for support through the Séneca AGR/2/FS/01D project

Verificación de equipos de aplicación de fitosanitarios en centrales hortofrutícolas

La Directiva 2009/128/CE, de 21 de octubre, del Parlamento Europeo y del Consejo, sobre Uso Sostenible de los Plaguicidas, establece que es necesario un sistema de inspección técnica periódica de los equipos de aplicación de plaguicidas ya en uso. A nivel estatal, el Real Decreto 1702/2011, que traspone al ordenamiento jurídico español la citada Directiva, establece que para la reducción los riesgos y los efectos del uso de los plaguicidas en la salud humana y el medio ambiente es necesario utilizar equipos de aplicación de productos fitosanitarios que funcionen correctamente. Con este objetivo, es obligatorio la verificación del cumplimiento de los requisitos sobre mantenimiento y puesta a punto de las máquinas de aplicación de productos fitosanitarios y establecer la normativa básica en materia de su inspección. En esta línea se ha publicado el Manual de inspección de equipos de aplicación de fitosanitarios en uso que trata la verificación de los pulverizadores hidráulicos, hidroneumáticos y neumáticos, pistolas y espolvoreadores y ahora, los autores, con el presente libro pretenden (mostrar, presentar, desarrollar...) en la medida de lo posible, una metodología que permita, siguiendo los requisitos establecido en la Directiva y el Real Decreto, la verificación de equipos de aplicación de fitosanitarios en centrales hortofrutícolas, teniendo en cuenta que no hay antecedentes ni normativa específica publicada hasta la fechaOrtí García, E.; Pérez Teruel, M. (2018). Verificación de equipos de aplicación de fitosanitarios en centrales hortofrutícolas. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/98114EDITORIA

Modelling Vineyard Spraying by Precisely Assessing the Duty Cycles of a Blast Sprayer Controlled by Pulse-Width-Modulated Nozzles

[EN] The flowrate control of spraying systems with pulse-width-modulated solenoid valves is currently being implemented for precision herbicide application in commodity crops, but solutions for fruit trees set in orchards that require higher pressures are mostly in the development stage. A reason for this has been the higher flowrate and pressure requirements of blast sprayers used for dense canopies typical of high value crops. In the present study, the duty cycles preset by an operator were compared to the actual ones estimated from measuring flowrates. A new developed air-assisted orchard sprayer with shelf hollow disc-cone nozzles was studied, such that flowrates and pressures were registered by a computer for different duty cycles commanded by an operator from 10% to 100% in intervals of 10%. In addition to sensor data, visual assessment was carried out via high-speed video images. The results showed that preset duty cycles were always more than 10% lower than the actual DC estimated from measured flowrates. The effective operational range of the duty cycles went from 20% to 80%. In general, the deviations in transitional periods were higher for lower duty cycles, being difficult to determine the real reduction in flowrate during the transition periods. A correction model has been proposed to adjust the preset duty cycles to make sure that the necessary spray flowrate is released as precisely commanded by prescription maps. Further research will be needed to verify the proper implementation of the developed correction model in field applications.This research has been funded by the Government of Spain through the Project "Smart spraying for a sustainable vineyard and olive trees" PIVOS (PID2019-104289RB).Saiz Rubio, V.; Ortiz Sánchez, MC.; Torregrosa, A.; Ortí, E.; Pérez Teruel, M.; Cuenca, A.; Rovira Más, F. (2023). Modelling Vineyard Spraying by Precisely Assessing the Duty Cycles of a Blast Sprayer Controlled by Pulse-Width-Modulated Nozzles. Agriculture. 13(2). https://doi.org/10.3390/agriculture1302049913