O Brasil é uma referência mundial na produção e exportação de citros, entretanto esse cultivo pode sofrer diversos problemas e perdas de produtividade por motivos diversos, como por exemplo, pragas. Para reduzir os riscos e perdas, torna-se interessante o uso de sistemas automatizados de monitoramento, justificando a necessidade de realizar a coleta de dados para determinar diversos fatores. Determinadas plantações, como a de citros, não podem ser monitoradas somente via solo ou somente via imagens aéreas, tornando necessário mesclar ambas as abordagens de acordo com o parâmetro a ser monitorado. Para a realização desse monitoramento devem ser utilizados robôs com habilidades distintas, robôs aéreos e robôs terrestres. Assim, é preciso designar as tarefas que cada robô realizará e também coordenar todos os robôs durante a execução do sistema como um todo, visando otimizar o processo de coleta de dados. Esse problema pode ser analisado e modelado como um problema de alocação de tarefas para robôs (Multi-Robot Task Allocation (MRTA)). Para resolver esse problema propõe-se um framework baseado em técnicas de cobertura de conjuntos e em mecanismo de mercado baseado em leilão. Teste simulados são realizados e demonstram que a presente proposta cumpre o papel na alocação das tarefas aos robôs. Além disso, visando a aplicação da solução proposta é projetado e desenvolvido uma plataforma robótica aérea (quadrirotor) de baixo custo utilizando peças prototipadas. Para o controle de estabilidade dessa plataforma, propõe-se um modelo matemático de acordo com os parâmetros inerciais do quadrirotor. Esse quadrirotor é utilizado em diversas aplicações reais, mostrando que o projeto desenvolvido pode ser reproduzido e destinado a execução de tarefas reais, como por exemplo a coleta de dados na agricultura de precisão. / Brazil is a world reference in the production and export of citrus, although this crop can suffer several problems and losses of productivity for diverse reasons, as for example, pests. In order to reduce risks and losses, it is interesting to use automated monitoring systems, justifying the need to perform data collection to determine several factors. Certain plantations, such as citrus plantations, can not be monitored only via soil or only via aerial images, making it necessary to merge both approaches according to the parameter to be monitored. To perform this monitoring, robots with different abilities, such asunmanned aerial vehicle (UAV) and unmanned ground vehicle (UCV) should be used. Therefore, it is necessary to assign the tasks that each robot will perform and also to coordinate all the robots during the execution of the system as a whole, in order to optimize the process of data collection. The problem can be studied and modeled as a task allocation problem for robots (MRTA). To solve this problem we propose a framework based set covering techniques and auction-based market mechanism. Simulated tests are performed and demonstrate that the present proposal fulfills the role in assigning tasks to robots. In addition, aiming at the application of the proposed solution is designed and developed a low cost aerial robotic platform (quadrirotor) which use prototyped parts. This quadrirotor is used in several real applications, showing that the developed project can be reproduced and destined to perform real tasks, such as data collection in precision agriculture.

Le contrôle de vol en formation se rapporte au contrôle de la trajectoire de plusieurs véhicules pour accomplir une tâche commune. La motivation du contrôle du vol en formation réside dans le fait que l'utilisation de plusieurs drones permet de réaliser des tâches plus complexes et que ne peut accomplir un drone unique. Les stratégies de commande de flotte de véhicules peuvent être classées en trois groupes principaux : la stratégie de vol type meneur-suiveur, celle basée sur comportement et l'approche utilisant un meneur virtuel. Chaque groupe se compose de différents véhicules et on suppose que les véhicules communiquent entre eux pour échanger des informations. Le contrôle de position pour des quadrirotors sous-actionnés ou des UAV VTOL a retenu l'intérêt de plusieurs chercheurs de la communauté scientifique. En raison de la nature sous-actionnée des UAV VTOL, l'attitude du système doit être utilisée afin de commander la position et la vitesse. En effet, la prise en compte des perturbations externes, des incertitudes sur la dynamique du système ainsi que l'objectif d'obtenir des résultats globaux rendent la synthèse de lois de commande plus difficile. Nous proposons, dans ce travail, un algorithme permettant l'extraction de l'attitude et une nouvelle formulation de la poussée pour la commande d'un drone. Cet algorithme utilise cette formulation de la force de poussée pour atteindre les objectifs en translation et utilise le vecteur quaternion unitaire comme consigne du sous-système en rotation. Cet algorithme est ensuite étendu au cas de la commande de vol en formation. Cinq contrôleurs de vol en formation sont développés et séparés dans deux groupes : l'approche structure virtuelle et l'approche meneur-suiveur. Les trois premiers contrôleurs de vol en formation utilisent l'approche structure virtuelle. La vitesse, les perturbations et les incertitudes de modèle dans la dynamique sont estimées par le biais d'un observateur et la technique de commande "backstepping" adaptative. La synthèse des deux derniers contrôleurs de vol en formation de vol est obtenue en utilisant l'approche meneur-suiveur. La formation utilisant cette approche pour des quadrirotors et pour le système du second degré est construite. Le changement de la configuration de la formation de vol est également simulé pour ces deux derniers contrôleurs de vol en formation. Dans chacun des cinq contrôleurs de vol en formation, la fonction d'évitement de collision construite à partir d'une fonction indicielle "lisse" est incluse. Cette fonction produit une force de poussée quand un quadrirotor évolue près des autres et d'une force de traction quand un quadrirotor évolue hors de la zone de détection. Les résultats de simulation prouvent que cette fonction d'évitement de collision fonctionne tout à fait correctement et qu'aucune collision entre les quadrirotors ni avec les obstacles ne se produit. En résumé, l'utilisation de la poussée, de l'algorithme d'extraction d'attitude et de la fonction d'évitement de collision, rend la synthèse des lois de commande plus facile et les résultats obtenus pour le vol en formation sont globaux / Formation control relates with the motion control of multiple vehicles to accomplish a common task. The motivation of formation control is because of the advantages achieved by using a formation of vehicles instead of a single one. Cooperative control approach can be cataloged into three main groups: leader-follower, behavior-based and virtual structure. Each group consists of individual vehicles and the communication allows the information be exchanged among vehicles. Position control for under-actuated quadrotors or VTOL UAVs has been focused in several group in the research community. Due to the under-actuated nature of VTOL UAVs, the system attitude must be used in order to control the position and velocity of the system. Moreover, the effect of external disturbance, uncertainty of the dynamics and the requirement of achieving the global results make the control design process more difficult. Developing from a global controller for a single quadrotor, a new thrust and attitude extraction algorithm is proposed. This algorithm allows transferring an intermediate control force to a thrust force to achieve the translational objective and an unit quaternion vector as a reference for the rotational subsystem. This algorithm is also embedded in the formation controller. Five formation controllers are developed and separated into two groups, virtual structure and leader-follower approach. The first three formation controllers are constructed by using the virtual structure approach. The unmeasured linear velocity, disturbance and uncertainty in the dynamics are solved by employing observer design and adaptive backstepping control design technique. The last two formation controllers are built by using the leader-follower approach. The leader follower formation for quadrotors and for second order system are constructed. The changing of formation shape in working time also is simulated in these last two formation controllers. In all five formation controllers, collision avoidance function constructed from a smooth step function is embedded. This function generates a pushing force when a quadrotor goes close to the others and a pulling force when a quadrotor travels out of the sensing range. The simulation results show that this collision avoidance function works quite effectively and there is no collision among quadrotors and obstacles. It can be summarized that by using the thrust and attitude extraction algorithm and the collision avoidance function, the control design process becomes easier and all the formation controllers achieve the global results

Submitted by Kamila Costa (kamilavasconceloscosta@gmail.com) on 2015-06-15T20:50:21Z No. of bitstreams: 1 Dissertacao-Adriano B dos S Frutuoso.pdf: 1799620 bytes, checksum: acda5b957dcaee1690413438f4a99e8e (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-06-16T14:58:57Z (GMT) No. of bitstreams: 1 Dissertacao-Adriano B dos S Frutuoso.pdf: 1799620 bytes, checksum: acda5b957dcaee1690413438f4a99e8e (MD5) / Approved for entry into archive by Divisão de Documentação/BC Biblioteca Central (ddbc@ufam.edu.br) on 2015-06-16T15:00:11Z (GMT) No. of bitstreams: 1 Dissertacao-Adriano B dos S Frutuoso.pdf: 1799620 bytes, checksum: acda5b957dcaee1690413438f4a99e8e (MD5) / Made available in DSpace on 2015-06-16T15:00:11Z (GMT). No. of bitstreams: 1 Dissertacao-Adriano B dos S Frutuoso.pdf: 1799620 bytes, checksum: acda5b957dcaee1690413438f4a99e8e (MD5) Previous issue date: 2015-02-02 / FAPEAM - Fundação de Amparo à Pesquisa do Estado do Amazonas / This work approaches the angles stability control of a quadrotor. The vehicle parts (mechanical structure and electronic devices), dynamic modeling, controllers design methodology and the experimental results are also presented. Attitude controllers were designed using a PD/H2 discrete control structure, which the gain of H2 part was performed by solving a convex optimization problem, described in linear matrix inequalities form. The experiments indicates that angles dynamic responses can be changed by setting the gain of H2, without modifying the gains of the proportional-derivative part. The results of PD/H2 controllers were compared with a PD controller, in order to evaluate the overshoot and settling time. / Neste trabalho é abordado o controle de estabilidade dos ângulos de atitude de um MAV (Micro Aerial Vehicle) do tipo quadrirrotor. São apresentadas as partes constituintes do veículo (estrutura mecânica e dispositivos eletrônicos), a modelagem dinâmica dos ângulos de atitude, a metodologia de projeto dos controladores de atitude e os resultados experimentais. Em relação ao projeto dos controladores de atitude, estes foram projetados usando estrutura de controle discreta combinada PD/H2, cuja sintonia do controlador H2 por realimentação de estados foi realizada a partir da resolução de um problema de otimização convexo descrito na forma de desigualdades matriciais lineares. Os experimentos mostraram que as respostas dinâmicas dos ângulos de atitude poderiam ser alteradas com o ajuste dos controladores H2, sem modificar os ganhos da parte proporcional-derivativa. Os resultados obtidos para os controladores PD/H2 foram comparados com os controladores PD, de modo a avaliar os seus desempenhos com relação a tempo de acomodação e overshoot.

Precision landing capability is a necessary development that must take place before unmanned aircraft systems (UAS) can realize their full potential in today's modern society. Current multirotor UAS are heavily reliant on GPS data to provide positioning information for landing. While generally accurate to within several meters, much higher levels of accuracy are needed to ensure safe and trouble-free operations in several UAS applications that are currently being pursued. Examples of these applications include package delivery, automatic docking and recharging, and landing on moving vehicles. The specific problem we consider is that of precision landing of a multirotor unmanned aircraft on a small barge at sea---which presents several significant challenges. Not only must we land on a moving vehicle, but the vessel also experiences random rotational and translational motion as a result of waves and wind. Because maritime operations often span long periods of time, it is also desirable that precision landing can occur at any time---day or night.In this work we present a complete approach for precision shipboard landing and address each of the aforementioned challenges. Our method is enabled by leveraging an on-board camera and a specialized landing target which can be detected in light or dark conditions. Features belonging to the target are extracted from camera imagery and are used to compute image-based visual servoing velocity commands that lead to precise alignment between the multirotor and landing target. To enable the multirotor to match the horizontal velocities of the barge, an extended Kalman filter is used to generate feed-forward velocity reference commands. The complete landing procedure is guided by a state machine architecture that incorporates corrections to account for wind, and is also capable of quickly reacquiring the landing target in a loss event. Our approach is thoroughly validated through full-scale outdoor flight tests and is shown to be reliable, timely, and accurate to within 4 to 10 centimeters.

整合了GPS、INS的無人飛行載具(Unmanned Aerial Vehicles, UAVs)，可提供安全、快速的資料蒐集方法，而能執行自動駕駛(automatic pilot)功能的UAV系統，更可提高資料蒐集的自動化程度。資料收集時，UAV系統中的GPS天線、INS系統以及像機的透視中心並不一致，欲以UAV系統執行航測任務時，須先了解UAV的系統幾何與特性，才能從GPS、INS的記錄資料中取得適當的外方位參數參考值。此外，目前的UAV系統多搭載非量測型像機(non-metric camera)獲取影像，但非量測型像機的內方位參數常以近景攝影測量的方式率定而得。然而，能以近景攝影測量方式獲得內方位參數的商業軟體很多，其所使用的函數模式卻未必完全相同，將影響內方位參數的率定成果，若再於空三平差過程中把不同軟體解得的內方位參數視為固定值，將使空三平差的結果產生較大的影像定位誤差。而自率光束法除了可用於近景攝影測量中的像機率定，也能應用於航空攝影測量中，將航測作業中的像坐標系統誤差模式化並加以改正，以提升該次作業的空三平差精度。因此，本研究以較安全的四旋翼UAV系統搭載非量測型像機獲取影像，比較：(1)一般航測方法（即光束法）執行空三平差、(2)使用自率光束法的空三平差、(3)先將所有影像觀測量以熟知的系統誤差模式改正後，再使用自率光束法的空三平差（以下簡稱預改正(pre-corrected)的自率光束法空三平差）所能達到的精度。測試結果顯示：使用預改正的自率光束法空三平差時，使用Brown(1976)與Ebner(1976)兩種附加參數模式，皆可得到最佳的空三平差精度，而使用Brown附加參數模式的自率光束法空三平差精度次之，且均比一般航測方法的空三平差精度佳。但於自率光束法的空三平差過程中使用Ebner的附加參數模式，所得的空三平差精度則最差。 / Unmanned aerial vehicles (UAVs) integrating with GPS and INS provide a safe and fast method for data acquisition. The UAVs which can implement automatic pilot promote the automation of data collection. In UAV systems, the GPS antenna and the INS system are not aligned with the perspective center, so that the GPS and INS records should be revised according to the geometry of UAV systems for exterior orientation references. And the cameras equipped with UAVs are often belonging to the non-metric camera, whose interior orientation parameters can be acquired by close-range photogrammetry softwares. However, there are several different camera models used in the softwares and the interior parameters calibrated by different softwares would not be the same, so that the interior parameters of the non-metric camera should not be regard as constant in aerotriangulation. Self-calibration can not only calibrate the camera in close-range photogrammetry but also model and compensate the departures from collinearity in aerotriangulation to promote the positioning accuracy. This study uses the images acquired from a safe UAV system, a Quadrotor UAV, and compares the results by using different aerotriangulation procedures. In this paper, the optimal accuracy can be obtained by using self-calibration in bundle adjustment with all measurements been pre-corrected for radial and decentering lens distortion. And the suboptumal accuracy can be obtained by using Brown’s (1976) added parameters in bundle adjustment, better than the results of using bundle adjustment. But using Ebner’s (1976) added parameters in bundle adjustment cannot help promoting the positioning accuracy.

Inspiré par les limitations de contrôleurs PID traditionnels et les différentes performances dans les cas idéals et réalistes, les quadrotors existants, leurs applications et leurs méthodes de contrôle ont été intensivement étudiés dans cette thèse. De nombreux challenges sont dévoilés: les systèmes embarqués ont des limites des ressources de calcul et de l'énergie; la dynamique est assez complexe et souvent mal connu; l'environnement a beaucoup de perturbations et d'incertitudes; de nombreuses méthodes de contrôle ont été proposées dans des scénarios idéaux dans la littérature sans comparaison avec d'autres méthodes. Par conséquent, cette thèse porte sur ces principaux points dans le contrôle de quadrotors.Tout d'abord, les modèles cinématiques et dynamiques sont proposés, y compris toutes les forces et couples aérodynamiques importants. Un modèle dynamique simplifié est également proposé pour certaines applications. Ensuite, la dynamique de quadrotor est analysée. En utilisant la théorie de la forme normale, le modèle de quadrotor est simplifié à une forme plus simple nommée la forme normale, qui présente toutes les propriétés dynamiques possibles du système d'origine. Les bifurcations de cette forme normale sont étudiées, et le système est simplifié à son point de bifurcation en utilisant la théorie de la variété du centre. Basé sur l'étude des applications de quadrotors, cinq scénarios réalistes sont proposés : un cas idéal, les cas avec la perturbation du vent, les incertitudes des paramètres, les bruits de capteurs et les fautes de moteur. Ces cas réalistes peuvent montrer plus globalement les performances des méthodes de contrôle par rapport aux cas idéaux. Un schéma déclenché par événements est également proposé avec le schéma déclenché par. Ensuite, la commande sans modèle est présentée, Il s'agit d'une technique simple mais efficace pour la dynamique non-linéaire, inconnue ou partiellement connue. La commande par backstepping et la commande par mode glissant sont également proposées pour la comparaison.Toutes les méthodes de contrôle sont mises en œuvre sous les schémas déclenchés par temps et par événements dans cinq scénarios différents. Basé sur l'étude des applications de quadrotors, dix critères sont choisis pour évaluer les performances des méthodes de contrôle, telles que l'erreur maximale absolue de suivi, la variance de l'erreur, le nombre d'actionnement, la consommation d'énergie, etc.

This thesis addresses the problems of design and control of small cooperative unmanned autonomous quadrotor aerial vehicles. A new approach is proposed, for the modeling of the system’s dynamics using linearized Piecewise AffineModels. The Piecewise Affine dynamic–models cover a large part of the quadrotor’s flight envelope while also taking into account the additive effects of environmental disturbances. The effects of aerodynamic forces and moments were also examined. A small quadrotor is designed and developed that emphasizes in the areas of increased on–board computational capabilities, state estimation and modular connectivity. Based on the translational and rotational system’s dynamics: a) a switching model predictive controller, b) an explicitly solved constrained finite time optimal control strategy, and c) a cascade control scheme comprised of classical Proportional Integral Derivative control scheme augmented with angular acceleration feedback, were designed and experimentally tested in order to achieve trajectory tracking under the presence of wind–gusts. The efficiency of the proposed control methods was verified through extended experimental studies. The final quadrotor design utilizes a powerful control unit, a sensor system that provides state estimation based on inertial sensors, ultrasound sonars, GPS and vision chips, and an efficient actuating system. The research effort extended in the field of unmanned aerial vehicles cooperation. Cooperation strategies were proposed in order to address the problems of: a) Forest Fire Monitoring and b) Unknown Area Exploration and Target Acquisition. The Forest FireMonitoring algorithm is formulated based on consensus systems theory formulated as a spatiotemporal rendezvous problem in between the quadrotors. The Area Exploration and Target Acquisition algorithm is formulated based on market–based approaches. / Η συγκεκριμένη διατριβή καταπιάνεται με τα προβλήματα της σχεδίασης και ελέγχου μικρού μεγέθους συνεργαζόμενων μη επανδρωμένων αεροσκαφών με έμφαση στα συστήματα Κάθετης Απογείωσης και Προσγείωσης και ιδιαίτερα στη συστήματα τύπου Quadrotor. Μια νέα προσέγγιση για την μοντελοποίηση της δυναμικής του συστήματος η οποία βασίζεται στη θεωρία των Piecewise Affine συστημάτων προτείνεται. Η μοντελοποίηση με βάση τη θεωρία των Piecewise Affine συστημάτων καλύπτει ένα μεγάλο μέρος του φακέλου πτήσης του αεροσκάφους καθότι συνυπολογίζει μέρος της μη-γραμμικότητας του συστήματος ενώ παράλληλα δίνει τη δυνατότητα να χρησιμοποιηθούν τα ιδιαίτερα ανεπτυγμένα εργαλεία του γραμμικού ελέγχου. Αναπτύσσεται νέα πειραματική πλατφόρμα αεροσκάφους τύπου quadrotor η οποία χαρακτηρίζεται από ιδιαίτερες ικανότητες υπολογιστικής ισχύος, αυτόνομη εκτίμηση κατάστασης, πολλαπλή συνδεσιμότητα και αποδοτικό σύστημα πρόωσης. Η τελική πλατφόρμα quadrotor ελικοπτέρου UPATcopter ενσωματώνει μικρουπολογιστικό σύστημα υψηλών δυνατοτήτων, ειδικά συστήματα εκτίμησης κατάστασης τόσο σε εσωτερικούς όσο και σε εξωτερικούς χώρους μέρος των οποίων αναπτύχθηκε στα πλαίσια της διατριβής και αποδοτικό υποσύστημα πρόωσης. Τρεις διαφορετικοί νόμοι ελέγχου αναπτύχθηκαν και δοκιμάστηκαν πειραματικά. Αρχικά δοκιμάσθηκε ένας Constrained Finite Time Optimal Controller, ο οποίος υπολογίζεται πολύ-παραμετρικά και συνυπολογίζει την επίδραση των περιορισμών εισόδου και κατάστασης. Ο συγκεκριμένος ελεγκτής υπολογίσθηκε με βάση μια οικογένεια Piecewise Affine αναπαραστάσεων του υποσυστήματος προσανατολισμού και δοκιμάσθηκε επιτυγχάνοντας αποδοτικό έλεγχο του προσανατολισμού του σκάφους. Ακολούθως δοκιμάσθηκε ένας Switching Model Predictive Control βασισμένος στην Piecewise Affine μοντελοποίηση του συστήματος ο οποίος επίσης συνυπολογίζει την επίδραση των περιορισμών του συστήματος και του ρόλου των διαταραχών. Με τη χρήση αυτού του ελεγκτή επιτεύχθηκε έλεγχος προσανατολισμού και θέσης του αεροσκάφους τόσο σε άπνοια όσο και υπό την επίδραση ισχυρών διαταραχών ανέμου. Επιπρόσθετα, δοκιμάσθηκε ελεγκτής βασισμένος στη θεωρία PID ελέγχου επαυξημένος με ανάδραση γωνιακής επιτάχυνσης του συστήματος. Τέλος, η έρευνα επεκτάθηκε και στις στρατηγικές συνεργασίας μη επανδρωμένων αεροσκαφών προτείνοντας δύο αλγόριθμους. Συγκεκριμένα προτάθηκε αλγόριθμος για την αντιμετώπιση των προβλημάτων επιθεώρησης δασικής πυρκαγιάς και αλγόριθμος εξερεύνησης μιας άγνωστης περιοχής από ομάδα ετερογενών αεροσκαφών.

Made available in DSpace on 2014-12-17T14:56:17Z (GMT). No. of bitstreams: 1 AndreTS_DISSERT.pdf: 5024853 bytes, checksum: c24b983c0dd71456069c554e6c343968 (MD5) Previous issue date: 2014-01-24 / Quadrotors aircraft are composed by four propellers mounted on four engines on a cross or x disposition, and, in this structure, the engines on the same arm spin in the same direction and the other arm in the opposite direction. By rotating each helix generates vertical upward thrust. The control is done by varying the rotational speed of each motor. Among the advantages of this type of vehicle can cite the mechanical simplicity of construction, the high degree of maneuverability and the ability to have vertical takeoffs and landings. The modeling and control of quadrirrotores have been a challenge due to problems such as nonlinearity and coupling between variables. Several strategies have been developed to control this type of vehicle, from the classical control to modern. There are air surveillance applications where a camera is fixed on the vehicle to point forward, where it is desired that the quadrotor moves at a fixed altitude toward the target also pointing forward, which imposes an artificial constraint motion, because it is not desired that it moves laterally, but only forwards or backwards and around its axes . This restriction is similar to the naturally existing on robots powered by wheels with differential drive, which also can not move laterally, due to the friction of the wheels. Therefore, a position control strategy similar to that used in this type of robot could be adapted for aerial robots like quadrotor. This dissertation presents and discusses some strategies for the control of position and orientation of quadrotors found in the literature and proposes a strategy based on dynamic control of mobile robots with differential drive, called the variable reference control. The validity of the proposed strategy is demonstrated through computer simulations / Quadrirrotores s?o ve?culos a?reos compostos por quatro h?lices montadas sobre quatro motores em uma disposi??o em cruz ou x, sendo que, nessa estrutura, os motores sobre o mesmo bra?o giram no mesmo sentido e os do outro bra?o em sentido oposto. Ao girar, cada h?lice gera empuxo vertical para cima. O controle ? feito variando-se a velocidade de rota??o de cada motor. Dentre as vantagens desse tipo de ve?culo pode-se citar a simplicidade mec?nica de constru??o, o alto grau de manobrabilidade que possui e a capacidade de pousos e decolagens verticais. A modelagem e o controle de quadrirrotores tem sido um desafio devido a problemas como n?o-linearidades e acoplamento entre vari?veis. V?rias estrat?gias j? foram desenvolvidas para o controle desse tipo de ve?culo, desde as de controle cl?ssico at? as mais modernas. H? aplica??es de supervis?o a?rea em que uma c?mera ? fixada no ve?culo de forma a apontar para a frente, onde ? desejado que o quadrirrotor procure se movimentar a uma altitude fixa em dire??o ao alvo tamb?m apontando para a frente, o que imp?e uma restri??o artificial de movimento, pois n?o ? desejado que se movimente lateralmente, mas para frente ou para tr?s e que gire ao redor dos seus eixos. Tal restri??o ? semelhante ?quela existente de maneira natural em rob?s movidos a rodas com acionamento diferencial, que tamb?m n?o podem se movimentar lateralmente, mas devido ao atrito das rodas. Portanto, uma estrat?gia de controle de posi??o semelhante ? usada nesse tipo de rob?s poderia ser adaptada para rob?s a?reos do tipo quadrirrotor. Este trabalho apresenta e discute algumas estrat?gias de controle de posi??o e orienta??o de quadrirrotores encontradas na literatura e prop?e uma estrat?gia baseada no controle din?mico de rob?s m?veis com acionamento diferencial, o chamado controle por refer?ncia vari?vel. A validade da estrat?gia proposta ? comprovada atrav?s de simula??es computacionais

O Brasil é uma referência mundial na produção e exportação de citros, entretanto esse cultivo pode sofrer diversos problemas e perdas de produtividade por motivos diversos, como por exemplo, pragas. Para reduzir os riscos e perdas, torna-se interessante o uso de sistemas automatizados de monitoramento, justificando a necessidade de realizar a coleta de dados para determinar diversos fatores. Determinadas plantações, como a de citros, não podem ser monitoradas somente via solo ou somente via imagens aéreas, tornando necessário mesclar ambas as abordagens de acordo com o parâmetro a ser monitorado. Para a realização desse monitoramento devem ser utilizados robôs com habilidades distintas, robôs aéreos e robôs terrestres. Assim, é preciso designar as tarefas que cada robô realizará e também coordenar todos os robôs durante a execução do sistema como um todo, visando otimizar o processo de coleta de dados. Esse problema pode ser analisado e modelado como um problema de alocação de tarefas para robôs (Multi-Robot Task Allocation (MRTA)). Para resolver esse problema propõe-se um framework baseado em técnicas de cobertura de conjuntos e em mecanismo de mercado baseado em leilão. Teste simulados são realizados e demonstram que a presente proposta cumpre o papel na alocação das tarefas aos robôs. Além disso, visando a aplicação da solução proposta é projetado e desenvolvido uma plataforma robótica aérea (quadrirotor) de baixo custo utilizando peças prototipadas. Para o controle de estabilidade dessa plataforma, propõe-se um modelo matemático de acordo com os parâmetros inerciais do quadrirotor. Esse quadrirotor é utilizado em diversas aplicações reais, mostrando que o projeto desenvolvido pode ser reproduzido e destinado a execução de tarefas reais, como por exemplo a coleta de dados na agricultura de precisão. / Brazil is a world reference in the production and export of citrus, although this crop can suffer several problems and losses of productivity for diverse reasons, as for example, pests. In order to reduce risks and losses, it is interesting to use automated monitoring systems, justifying the need to perform data collection to determine several factors. Certain plantations, such as citrus plantations, can not be monitored only via soil or only via aerial images, making it necessary to merge both approaches according to the parameter to be monitored. To perform this monitoring, robots with different abilities, such asunmanned aerial vehicle (UAV) and unmanned ground vehicle (UCV) should be used. Therefore, it is necessary to assign the tasks that each robot will perform and also to coordinate all the robots during the execution of the system as a whole, in order to optimize the process of data collection. The problem can be studied and modeled as a task allocation problem for robots (MRTA). To solve this problem we propose a framework based set covering techniques and auction-based market mechanism. Simulated tests are performed and demonstrate that the present proposal fulfills the role in assigning tasks to robots. In addition, aiming at the application of the proposed solution is designed and developed a low cost aerial robotic platform (quadrirotor) which use prototyped parts. This quadrirotor is used in several real applications, showing that the developed project can be reproduced and destined to perform real tasks, such as data collection in precision agriculture.

No description available.