The adoption of precision agriculture techniques finds great limitation because of the high cost, not always guaranteeing the expected economic return. Among the consequence of this elevated cost it is the restriction use of this technology in small farmers, characterized by the family farm. The present work approaches a bibliographical study about the situation of the family farm in Brazil, pointing to regional focuses. In order to complement this study was made a diagnosis on the existing agricultural machines park and the mechanization used intensity in the state of Rio Grande do Sul, aiming a reflection about the role of the agricultural machine industries for small farmers. This work was dedicated to apply precision agriculture techniques in a small farmer where an area of 10,9 hectares was managed with precision agriculture tools and appropriate information technology to the socioeconomic farmer profile. In order to reach this general objective it was proposed the following specific objectives: a) to identify the horizontal spatial variability of the soil attributes through fertility maps; b) to apply fertilizers in different doses for each handling zones; c) to measure soil resistance to penetration and wheat leaf chlorophyll; d) to make yield map; e) to take note of production costs and to elaborate liquid revenue map for wheat culture; f) to evaluate performance of agricultural machines using GPS tracker. As some results, it was found horizontal spatial variability in soil for phosphorus and potassium and chlorophyll in wheat leaf; it was possible to apply different quantities of fertilizer using seeding and centrifugal broadcaster spreaders without automatic variable rate. In this area, the average of wheat yield was 2427 kg.ha-1, changing from 1915 to 3151 kg.ha-1. Considering the relationship between productivity and production costs, the liquid revenue varied from R$ 14,00 to 358,00 per hectare and had average of R$ 183,48 per ha. The individual crossing among digital models evidenced correlation of 48,6% between productivity and liquid revenue. In general way, precision agriculture tools can help the farmer to know better and more precisely each part of area destined to agricultural activity. It allows to increase the production efficiency through a better soil handling and rational use of the inputs, reducing costs, and other times, increasing productivity. / A adoção de técnicas associadas à agricultura de precisão encontra grande limitação devido ao seu elevado custo implantação, nem sempre garantindo o retorno esperado. Entre as conseqüências deste elevado custo está a restrição do uso dessa tecnologia em pequenas propriedades, caracterizadas pela agricultura familiar. O presente trabalho inicialmente aborda um estudo bibliográfico sobre o retrato da situação da agricultura familiar no Brasil e apontando para enfoques regionais. Complementam este estudo um diagnóstico sobre a frota de máquinas agrícolas existente e os índices de mecanização nas diversas regiões do Rio Grande do Sul, levando à reflexão sobre o papel da indústria de máquinas agrícolas para pequenas propriedades. O trabalho foi dedicado à aplicação de técnicas de agricultura de precisão em uma pequena propriedade, onde se preocupou em gerenciar uma área de 10,9 hectares com ferramentas e tecnologia de informação mais adequada ao perfil agrosocioeconômico do produtor. Para atender este proposto, os objetivos específicos foram: a) identificar a variabilidade espacial horizontal dos atributos de solo através de mapas de fertilidade; b) aplicar fertilizantes em diferentes doses por zonas de manejo; c) medir resistência à penetração do solo e clorofila na folha de trigo; d) confeccionar mapa de produtividade; e) apontar os custos de produção e elaborar mapa de receita líquida da cultura do trigo; e f) avaliar o desempenho operacional das máquinas agrícolas através de rastreamento por GPS. Entre os principais resultados, encontrou-se variabilidade horizontal dos teores de fósforo e potássio no solo e de clorofila no trigo; foi possível aplicar diferentes doses de fertilizantes utilizando semeadora e distribuidor centrífugo de taxa fixa. A produtividade média de trigo na área foi de 2427 kg.ha-1, oscilando entre 1915 e 3151 kg.ha-1. Considerando a relação produtividade e custo, a receita líquida variou de R$ 14,00 a 358,00 por hectare e em média R$ 183,48 por ha. O cruzamento individual entre modelos digitais evidenciou correlação de 48,6% entre produtividade e receita líquida. De uma forma geral, as ferramentas de agricultura de precisão podem ajudar ao produtor a conhecer melhor e mais detalhadamente cada parcela de sua área destinada à atividade agrícola, permitindo aumentar a eficiência produtiva através do manejo e do uso racional dos insumos, diminuindo custos, e por vezes, aumentando a produtividade.

La thématique étudiée dans ce mémoire est axée sur la préservation de la stabilité dynamique de véhicules évoluant en environnement naturel. En effet, la mobilité en milieu tout-terrain est une activité particulièrement pénible et dangereuse en raison de la nature difficile de l'environnement de conduite et de la reconfigurabilité des machines. Le caractère changeant et incertain des interactions rencontrées entre des véhicules à dynamique complexe et variable et leur environnement entraîne régulièrement des risques accrus de renversement et/ou de perte de contrôle (dévalement, dérapage déclenché par une perte soudaine d'adhérence) pour le conducteur. Une forte accidentalité mortelle est, en effet, recensée dans ce secteur, en particulier, dans le milieu agricole ou le renversement de véhicule est classé comme étant la première cause de mortalité au travail. A l'heure actuelle, les approches existantes sur la stabilité d'engins agricoles sont qualifiées à juste titre de passives car elles ne permettent pas d'éviter que les accidents ne se produisent. Par ailleurs, la transposition directe des solutions de sécurité active du secteur de l'automobile (ABS, ESP) s'est révélée inadaptée aux véhicules tout-terrain a cause des hypothèses simplificatrices (routes plates et homogènes, conditions d'adhérence constantes, etc.) dont souffre la conception de ces dispositifs. Ainsi, le développement de systèmes actifs de sécurité prenant en compte les spécificités de la conduite en milieu tout-terrain se révèle être la meilleure voie d'amélioration à suivre. Eu égard à ces circonstances, ce projet se propose d'adresser cette problématique en étudiant des métriques de stabilité pertinentes permettant d'estimer et d'anticiper en temps réel les risques afin de permettre des actions correctives pour la préservation de l'intégrité des machines tout-terrain. Afin de faciliter l'industrialisation du dispositif actif de sécurité conçu, l'une des contraintes sociétales et commerciales de ce projet a été l'utilisation de capteurs compatibles avec le coût des machines visées. L'objectif ambitieux de cette étude a été atteint par différentes voies. En premier lieu, une approche de modélisation multi-échelle a permis de caractériser l'évolution dynamique de véhicules en milieu tout-terrain. Cette approche à dynamique partielle a offert l'avantage de développer des modèles suffisamment précis pour être représentatifs du comportement réel de l'engin mais tout en présentant une structure relativement simple permettant la synthèse d'asservissements performants. Puis, une étude comparative des avantages et des inconvénients des trois grandes familles de métriques répertoriées dans la littérature a permis de mettre en exergue l'intérêt des métriques analytiques à modèle dynamique par rapport aux catégories de critères de stabilité dits statiques et empiriques. Enfin, l'analyse approfondie des métriques dynamiques a facilité le choix de trois indicateurs (Lateral and Longitudinal Load Transfer (LLT), Force Angle Stability Measurement (FASM) et Dynamic Energy Stability Measurement (DESM)) qui sont représentatifs d'un risque imminent de renversement du véhicule. La suite du mémoire s'appuie sur la théorie d'observation pour l'estimation en ligne des variables non directement mesurables en milieu tout-terrain telles que les rigidités de glissement et dérive du pneumatique. Jumelée aux différents modèles dynamiques du véhicule, la synthèse d'observateurs a permis donc d'estimer en temps réel les efforts d'interaction pneumatiques-sol nécessaires à l'évaluation des indicateurs d'instabilité. Le couplage de ces modèles multi-échelles à la théorie d'observation a ainsi constitué un positionnement original à même de briser la complexité de la caractérisation de la stabilité de véhicules à dynamiques complexes et incertaines. (...) / This work is focused on the thematic of the maintenance of the dynamic stability of off-road vehicles. Indeed, driving vehicles in off-road environment remains a dangerous and harsh activity because of the variable and bad grip conditions associated to a large diversity of terrains. Driving difficulties may be also encountered when considering huge machines with possible reconfiguration of their mechanical properties (changes in mass and centre of gravity height for instance). As a consequence, for the sole agriculture sector, several fatal injuries are reported per year in particular due to rollover situations. Passive protections (ROllover Protective Structure - ROPS) are installed on tractors to reduce accident consequences. However, protection capabilities of these structures are very limited and the latter cannot be embedded on bigger machines due to mechanical design limitations. Furthermore, driving assistance systems (such as ESP or ABS) have been deeply studied for on-road vehicles and successfully improve safety. These systems usually assume that the vehicle Center of Gravity (CG) height is low and that the vehicles are operating on smooth and level terrain. Since these assumptions are not satisfied when considering off-road vehicles with a high CG, such devices cannot be applied directly. Consequently, this work proposes to address this research problem by studying relevant stability metrics able to evaluate in real time the rollover risk in order to develop active safety devices dedicated to off-road vehicles. In order to keep a feasible industrialization of the conceived active safety device, the use of compatible sensors with the cost of the machines was one of the major commercial and societal requirements of the project. The ambitious goal of this study was achieved by different routes. First, a multi-scale modeling approach allowed to characterize the dynamic evolution of off-road vehicles. This partial dynamic approach has offered the advantage of developing sufficiently accurate models to be representative of the actual behavior of the machine but having a relatively simple structure for high-performance control systems. Then, a comparative study of the advantages and drawbacks of the three main families of metrics found in the literature has helped to highlight the interest of dynamic stability metrics at the expense to categories of so-called static and empirical stability criteria. Finally, a thorough analysis of dynamic metrics has facilitated the choice of three indicators (Longitudinal and Lateral Load Transfer (LLT), Force Angle Stability Measurement (FASM) and Dynamic Energy Stability Measurement (DESM)) that are representative of an imminent rollover risk. The following of the document is based on the observation theory for estimating online of variables which are not directly measurable in off-road environment such as slip and cornering stiffnesses. Coupled to the dynamic models of the vehicle, the theory of observers has helped therefore to estimate in real time the tire-soil interaction forces which are necessaries for evaluating indicators of instability. The coupling of these multiscale models to the observation theory has formed an original positioning capable to break the complexity of the characterization of the stability of vehicles having complex and uncertain dynamics. (...)

This master’s thesis was conducted in the spring of 2024 at Väderstad AB, a companyknown for producing high-performance agricultural machines, such as seeding machines. Among these machines, the Seed Hawk 600-900C is an important machine for thecompany’s future. The innovation department at Väderstad has developed an automatic Bag Slicer, capable of slicing large bags of seeds/fertilizer without requiring the farmer to climb onto the machine, a cumbersome and hazardous task. Several challenges arisein integrating the Bag Slicer onto their machines, which has hindered its implementation.These challenges have been thoroughly investigated, and one has been selected as thepriority for resolution: enabling the observation of the filling process without the need for climbing onto the hopper. To address this challenge, theoretical studies, concept development, and investigations in the 3D software Blender have been conducted. Creo Parametric was utilized to assemble the Bag Slicer onto the Seed Hawk machine and design other essential components. Coloring, animations, and renderings were created in Blender to create a configuration of cameras, lights, cables, and investigate their properties. This configuration provides users witha comprehensive overview of the filling process and enables operation of the Bag Slicerin the field from the safety of a tractor or wheel loader. Consideration has been given to the conditions occurring inside and around the Seed Hawk machine when specifyingall the different components and operational requirements. The entire configuration was compiled into a complete list of specifications, constituting the main result of this thesis.