18 research outputs found

    Cassava and its harvesting | La yuca y su cosecha

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    Cassava (Manihot esculenta Crant) is one of the most important economic crops in tropical and subtropical areas. The average yield, compared to its potential, is often low. Harvesting is done with several procedures in global areas; the operation is difficult, costly and of low productivity in most regions. The primary objectives of  this study were: to assess the techniques of cassava harvest under different methods, land preparation and planting, damage or break of tubers, manual and mechanized harvesting, adaptation of varieties, the effect of agronomic parameters, soil moisture during harvest, new hand tools and mechanical harvesting. The evaluation methods consisted of literature reviewing, explorations, examination of existing tools, modifications and mathematical analysis with design and calculation. As a result, an assessment is made of manual and mechanized techniques for harvesting, and recommendations are provided about mechanical properties, devices for tuber collection, genetics, seed and importance of soil moisture during harvest. Key words: Soil moisture, tillage, varieties, planting, harvesting hand tools, mechanized harvesters.  RESUMEN La yuca (Manihot esculenta Crant) es uno de los cultivos económicos más importantes en las zonas tropicales y subtropicales. El rendimiento promedio, comparado con su potencial, suele ser bajo. La cosecha se realiza con varios procedimientos en áreas globales conocidas; la operación es difícil, costosa y de baja productividad en la mayoría de las regiones. Los objetivos principales de este estudio fueron: evaluar las técnicas de cosecha de yuca bajo diferentes métodos, la plantación, el daño o rotura de los tubérculos, la cosecha manual y mecanizada, la adaptación de las variedades, el efecto de los parámetros agronómicos, la humedad del suelo durante la cosecha, nuevas herramientas manuales y la recolección mecánica. Los métodos consistieron en revisión de la literatura, examen de las herramientas existentes, modificaciones y análisis matemático con diseño y cálculo. Como resultado, se hace una evaluación de la técnica manual y mecanizada para la cosecha, y se formulan recomendaciones de características mecánicas, dispositivos de recolección, genética, semilla e importancia de la humedad del suelo durante la cosecha. Palabras clave: Humedad del suelo, labranza, variedades, siembra, herramientas manuales para la cosecha, cosecha mecanizada

    Tractive performance of 4x4 tyre treads on pure sand.

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    This thesis examined the difficulties of generating traction from 4x4 (light truck) tyres in pure sand conditions. Investigations conducted in the Cranfield University Soil Dynamics Laboratory measured the tractive performance of a range of production and prototype 4x4 tyre tread patterns to quantify the effect of tread features upon tractive performance. The investigation also quantified the amount of sand displacement instantaneously occurring beneath the tyre, by a novel application of radio frequency identification (RFID) technology, which determined sand displacements to an accuracy of ±5.5 mm. A limited number of normal contact stress measurements were recorded using a TekScan normal pressure mapping system. This technology was employed in a new manner that allowed pressure distributions to be dynamically recorded on a deformable soil surface. Models were developed or adapted to predict rolling resistance, gross thrust of a tyre and the gross thrust effect due to its tread. Net thrust was predicted from refined versions of equations developed by Bekker to predict gross thrust and rolling resistance. These were modified to account for dynamic tractive conditions. A new tread model proposed by the author produced a numerical representation of the gross thrust capability of a tread based on factors hypothesised to influence traction on loose sand. This allowed the development of a relationship between the features of the tread and its measured gross thrust improvement (relative to a plain tread tyre), from which a total relationship was developed. The tread features were also, in combination with the wheel slip, related to the sand displacements and net thrusts simultaneously achieved. The sand displacement results indicated that the majority of the variation in displacement between the different treads occurred in the longitudinal (rearward) direction. This effect was influenced by the wheel slip, as increased slip caused greater displacements, so the differences between the treads were greater at higher slips. The treads that generated the highest relative displacements also derived the higher gross thrusts (up to +5% extra gross thrust compared to a plain tread), although at the higher slips this also caused increased sinkage. As sinkage increased, the rolling resistance increased at a fester rate then the gross thrust, and thus the net thrust reduced. To prevent this effect the wheel slip should be limited to a maximum of 20% at low forward speeds (approximately 5 km/h). Current market forces dictate that the biggest benefit that tyre manufacturers could offer in desert market regions would be to optimise road-biased tyres to suit loose sand conditions. The modelling developed indicated that this could be achieved by maximising the number of lateral grooves (and thus lateral edges) featured on a tread, however care would have to be exercised so as not to compromise the necessaiy on-road capability. The models could also be used to quantifiably determine from a choice of possible tyre treads, the tread that would offer most traction on pure loose sand

    Computer Vision Algorithms For An Automated Harvester

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    Image classification and segmentation are the two main important parts in the 3D vision system of a harvesting robot. Regarding the first part, the vision system aids in the real time identification of contaminated areas of the farm based on the damage identified using the robot’s camera. To solve the problem of identification, a fast and non-destructive method, Support Vector Machine (SVM), is applied to improve the recognition accuracy and efficiency of the robot. Initially, a median filter is applied to remove the inherent noise in the colored image. SIFT features of the image are then extracted and computed forming a vector, which is then quantized into visual words. Finally, the histogram of the frequency of each element in the visual vocabulary is created and fed into an SVM classifier, which categorizes the mushrooms as either class one or class two. Our preliminary results for image classification were promising and the experiments carried out on the data set highlight fast computation time and a high rate of accuracy, reaching over 90% using this method, which can be employed in real life scenario. As pertains to image Segmentation on the other hand, the vision system aids in real time identification of mushrooms but a stiff challenge is encountered in robot vision as the irregularly spaced mushrooms of uneven sizes often occlude each other due to the nature of mushroom growth in the growing environment. We address the issue of mushroom segmentation by following a multi-step process; the images are first segmented in HSV color space to locate the area of interest and then both the image gradient information from the area of interest and Hough transform methods are used to locate the center position and perimeter of each individual mushroom in XY plane. Afterwards, the depth map information given by Microsoft Kinect is employed to estimate the Z- depth of each individual mushroom, which is then being used to measure the distance between the robot end effector and center coordinate of each individual mushroom. We tested this algorithm under various environmental conditions and our segmentation results indicate this method provides sufficient computational speed and accuracy

    River Lune processes. A study of change in the River Lune catchment and recommendations for flood defence management

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    There has been a perception of increasing river channel instability in north west rivers and the River Lune in particular in recent decades. This has been attributed variously to: (a) long-term trends in precipitation-runoff regime; (b) changes in land-use such as moor-draining and sub-soil draining such that the river is more flashy than previously, and (c) a change in the magnitude-frequency relationships of flow such that high discharges are occurring with increased frequency. Resources are available in the form of rainfall and runoff records, archived information on channel planform, land use statistics and local engineering experience which have not been jointly and fully evaluated. Effective interpretation of the nature of channel change through time with respect to this resource may enhance the Environment Agency's ability to manage the river channel efficiently in the future and will aid the development of effective policy. The results of this study will for the first time, provide robust guidance with respect to long-term channel adjustment and the appropriate management options. The research provides suggestions as to how policy might be developed taking account of other pertinent factors

    Development of an Autonomous Robotic Mushroom Harvester

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    The process of development of a new robot is one of the modern technological arts. This process involves multiple complex steps and recursive approach. In this project, a solution for automatic harvesting of mushrooms is developed. In order to design an effective solution, it is necessary to explore and take into consideration the limitations of grasping very soft and fragile objects (particularly mushrooms). We will elaborate several strategies of picking and analyze each strategy to formulate the design requirements, develop a solution, and finally, evaluate the efficiency of the proposed solution in actual farm conditions for real mushrooms. The mushroom farm used in our study utilizes Dutch shelving systems, which pose stringent space requirements on the construction. The main challenge in this project is the development of a robot with 7 degrees of freedom (DOF), which would fit into the existing infrastructure with no or minimal changes on the existing infrastructure

    Modeling of the energy requirements of a non-row sensitive corn header for a pull-type forage harvester

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    With the constant diversification of cropping systems and the constant increase in farm size, new trends are observed for agricultural machinery. The increase in size of the machinery and the increasing number of contractors has opened the market to selfpropelled forage harvesters equipped with headers that can harvest row crops in any direction, at any spacing. High-capacity pull-type forage harvesters are also in demand but no commercial model offers non-row sensitive corn headers. The objectives of this research were to collect data and develop models of specific energy requirements for a prototype non-row sensitive corn header. The ability to better understand the processes involved during the harvesting and the modeling of these allowed the formulation of recommendations to reduce the loads on the harvester and propelling tractor. Three sets of experiments were performed. The first experiment consisted of measuring specific energy requirements of a non-row sensitive header, in field conditions, and to compare them with a conventional header. The prototype tested was found to require approximately twice the power than a conventional header of the same width, mostly due to high no-load power. Some properties of corn stalk required for the modeling of the energy needs, that were not available in literature, were measured in the laboratory. Those include the cutting energy with a specific knife configuration used on the prototype header and the crushing resistance of corn stalk. Two knife designs were compared for required cutting energy and found not to be significantly different with values of 0.054 J/mm2 of stalk cross-section area and 0.063 J/mm2. An average crushing resistance of 6.5 N per percent of relative deformation was measured. Three mathematical models were developed and validated with experimental data to predict and understand the specific energy needs of the non-row sensitive header. An analytical model was developed based on the analysis of the processes involved in the harvesting. A regression model was developed based on throughput and header speed and a general model suggested in literature was also validated with the data. All three models were fitted with coefficient of correlation between 0.88 to 0.90

    Agriculture and environment

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    Aqueous & Non-Aqueous Phase Tracer Migration Through Differing Soil Textures

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    The National Grid Transco Company sponsored this project in order to promote the understanding of NAPL migration through b-horizon soils and retarding effects upon non aqueous species migration. Soil structure and texture was also studied using conservative (Bromide) and non-conservative (Phosphate) tracers. Experimental data was produced using a laboratory ½ metre scale automated lysimeter designed and constn1cted at Plymouth. The tracers were compared before oil injection, to calibrate differences in soil texture, and after oil injection to detect any changes in the flow patterns caused by the oil injection. It was found that the Crediton, Sollom and Conway soils respectively offered least resistance to the tracers with the non-conservative tracer behaving much more unpredictably than the conservative tracer. After oil injection it could be seen that the oil had heavily retarded the ability of the tracers to migrate from the injection site. This retardation was identified as analogous to perturbations of the soil structure. Statistical analysis of the data showed that the experiments were all internally self consistent and visible patterns could be seen in the corrected data caused by inclusion of oil in the injection site. Methods of dispersal for the oil and tracer are suggested in the concluding chapter with references to the work of previous authors. Development of a hazard assessment framework was facilitated by the simulation of soil structures using a pedo transfer function developed at the National Soils Resource Institute. To allow the modelling of soils the Pore-Cor software had an annealed simplex algorithm integrated into the data inversion engine to allow the simulation of 3-D soil structures using 2-D data from pedo transfer functions or experimentally derived water retention curves. An extensive sensitivity analysis upon the model highlighted limitations, due to the data set the current pedo transfer function is based upon. It was suggested that inclusion of choices of different pedo transfer functions could be used to overcome this problem. A suitable framework was derived for the identification of priority soils using a validated computer model. Experimental data was compared to the simulated data in order to try and develop an understanding of practical upscaling of the data. The use of the "Scaleway" method is discussed in the concluding Chapter.Tbe National Grid Transco pl

    Garras con sensores táctiles intrínsecos para manipular alimentos con robots

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    [EN] The primary handling of food with robots calls for the development of new manipulation devices, especially when products are easily damaged and have a wide range of shapes and textures. These difficulties are even greater in the agricultural industry because the quality of the products is also checked during the manual handling process. This PhD dissertation provides solutions to these issues and helps to further introduce robotics into the handling of food. Several methods for handling food are included and analyzed, and specific solutions are proposed and then validated with prototypes. The research focuses on devices capable of adapting themselves to the shapes of the products without increasing the complexity of the mechanism. After analyzing several different solutions, the method chosen involves the use of under-actuated mechanisms, compliant mechanisms and fingers with pads filled with granular fluids. These fluids can behave as quasi-liquids or quasi-solids due to the jamming transition, which provides a soft initial grasp and can support high stresses during fast movements performed by the robot. The additive manufacturing process provides an opportunity to develop robot grippers that are lighter, simpler, more flexible and cheaper. By using this process elastic mechanisms are manufactured in a single part, which are equivalent to mechanisms with several rigid parts connected by joints. Laser sintering is employed to produce pneumatic actuators, with different types of motions, based on the elastic properties of the materials used in this manufacturing process. As a result, the systems can be simplified to achieve grippers, with several fingers, that are produced as a single part. In order to estimate the freshness and quality of agricultural products while they are being grasped, accelerometers are added to the fingers of several grippers. Accelerometers are economical and act as intrinsic tactile sensors. They can be easily embedded, thereby reducing the risk of getting damaged due to contact with the product, and allow each of the grasping phases to be identified. To achieve good performance of the accelerometers, a specific process is defined for the robot gripper, which touches the products a few times. In addition, several gripper prototypes are manufactured with diverse under-actuated mechanisms, jamming systems, and a new program that processes the signals from the accelerometers using different procedures in order to obtain parameters that can be used to estimate the quality of products. These parameters are correlated with data from destructive tests that are commonly used as a reference. The best performance of the accelerometers is achieved when the finger employs a granular fluid, a correlation coefficient of 0.937 being accomplished for the ripeness of mangoes and 0.872 for the firmness of eggplants.[ES] La manipulación primaria de alimentos con robots precisa del desarrollo de nuevos sistemas de manipulación especialmente cuando los productos son sensibles al daño y presentan una amplia variabilidad de formas y texturas. En el sector agroalimentario las dificultades son aún mayores ya que la manipulación manual sirve además para inspeccionar los productos durante el proceso. Está tesis aporta soluciones a estos problemas facilitando la incorporación de la robótica. En la tesis se recopilan y analizan diversas soluciones para poder manipular alimentos proponiendo soluciones concretas que luego son validadas con prototipos. La investigación se centra en aquellos sistemas que son capaces de auto adaptarse a las formas de los productos sin incrementar la complejidad del mecanismo. Tras analizar diversas técnicas se propone el uso de mecanismos infra-actuados, mecanismos flexibles y dedos con fluidos granulares que, al estar encerrados dentro de una membrana, se comportan como cuasi-líquidos o cuasi-sólidos gracias a la transición jamming, permitiendo un agarre inicial suave y la posibilidad de transmitir esfuerzos elevados durante los movimientos del robot. En la búsqueda de garras más ligeras, sencillas, flexibles y económicas se aprovecha la oportunidad que brinda la tecnología de fabricación aditiva de material. Gracias a este proceso se fabrican mecanismos flexibles realizados en una única pieza y que equivalen a mecanismos de garras realizados con varias piezas rígidas unidos por articulaciones. Mediante el sinterizado por láser, se fabrican actuadores neumáticos, con diversos tipos de movimiento, basados en la flexibilidad del material empleado en su fabricación. En conjunto se simplifican los sistemas llegando a realizar garras flexibles de varios dedos fabricadas en una única pieza. Para evaluar la calidad y frescura de los productos agroalimentarios durante el agarre se emplean acelerómetros localizados en los dedos de varias garras. Los acelerómetros son económicos y se comportan como sensores táctiles intrínsecos, están fuera del contacto directo con el producto evitando desgastes por contacto y permiten identificar las distintas fases de agarre. Para lograr esto se desarrolla un proceso específico del robot con la garra, que palpa varias veces el producto. Se fabrican diversos tipos de garra con distintas tecnologías de mecanismos infra-actuados y sistemas jamming y se programa un algoritmo original de procesado de señal que con diversas técnicas es capaz de extraer parámetros de los acelerómetros que sirven para evaluar la calidad de los productos. Estos parámetros son correlacionados con los datos de ensayos destructivos que son habitualmente empleados como referencia. Las mejores capacidades se consiguen empleando garras con jamming lográndose coeficientes de correlación de 0.937 en índices de madurez con mangos y 0.872 en firmeza de berenjenas.[CA] La manipulació primària d'aliments amb robots precisa del desenvolupament de nous sistemes de manipulació especialment quan els productes són sensibles al dany i presenten una àmplia variabilitat de formes i textures. En el sector agroalimentari les dificultats són encara més grans ja que la manipulació manual serveix a més per a inspeccionar els productes durant el procés. Aquesta tesi aporta solucions a aquests problemes facilitant la incorporació de la robòtica. En la tesi es recopilen i analitzen diverses solucions per a poder manipular aliments proposant solucions concretes que després són validades amb prototips. La investigació es centra en aquells sistemes que són capaços d'auto adaptar-se a la forma dels productes sense incrementar la complexitat del mecanisme. Després d'analitzar diverses tècniques es proposa l'ús de mecanismes infra-actuats, mecanismes flexibles i dits amb fluids granulars que, tancats dins d'una membrana, es comporten com quasi-líquids o quasi-sòlids gràcies a la transició jamming, permetent una prensió inicial suau i la possibilitat de transmetre esforços elevats durant els moviments del robot. En la recerca d'urpes més lleugeres, senzilles, flexibles i econòmiques s'aprofita l'oportunitat que brinda la tecnologia de fabricació additiva de material. Gràcies a aquest procés es fabriquen mecanismes flexibles realitzats en una única peça i que equivalen a mecanismes d'urpes realitzats amb diverses peces rígides unides per articulacions. Mitjançant el sinteritzat per làser, es fabriquen actuadors pneumàtics, amb diversos tipus de moviment, basats en la flexibilitat del material emprat en la seva fabricació. En conjunt es simplifiquen els sistemes arribant a realitzar urpes flexibles de diversos dits fabricades en una única peça. Per a avaluar la qualitat i frescor dels productes agroalimentaris durant la manipulació s'empren acceleròmetres localitzats en els dits de diverses urpes. Els acceleròmetres són econòmics i es comporten com a sensors tàctils intrínsecs, sense estar en contacte directe amb el producte evitant desgastos per aquest motiu, i permeten identificar les diferents fases d'prensió. Per aconseguir això es desenvolupa un procés específic del robot amb l'urpa, que palpa diverses vegades el producte. Es fabriquen diversos tipus d'urpa amb diferents tecnologies de mecanismes infra-actuats i sistemes jamming i es programa un algoritme original de processat de senyal que, amb diverses tècniques, és capaç d'extreure paràmetres dels acceleròmetres que serveixen per a avaluar la qualitat dels productes. Aquests paràmetres són correlacionats amb les dades d'assajos destructius que són habitualment emprats com a referència. Les millors capacitats s'aconsegueixen emprant urpes amb jamming assolint-se coeficients de correlació de 0,937 en índexs de maduresa amb mangos i 0,872 en fermesa d'albergínies.Blanes Campos, C. (2016). Garras con sensores táctiles intrínsecos para manipular alimentos con robots [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/68481TESI

    Ergonomic aspects of harvesting apples by hand

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    Following Parliamentary debates in 1980 on the quality of fresh market produce, in particular apples, a grant was awarded for research into the ergonomics of harvesting and marketing apples. The objectives were to study ways to improve the quality of English apples in the market place by examining the ergonomics and the cost effectiveness of methods of hand-picking apples. This involved: participation observation studies, observation of professional pickers, surveys and questionnaires, in an effort to define problem areas and to prepare a criticism of present methods. Additional studies of potential fatigue and stress both in fieldwork and in simulation were intended as a preliminary investigation to devise a preferred picking method and to redesign picking and handling aids where appropriate. [Continues.
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