The usage of autonomous ground vehicles is growingextensively. Therefore, it is important to gain a better understand-ing for the fundamentals of their communication network. Inthis paper, three important areas will be considered: Trajectorytracking, formation control and collision avoidance. Firstly,trajectory tracking is implemented for unicycles to direct them toa reference path. Secondly, formation control is examined for twoapproaches: A method based on virtual structure with a presettrajectory for unicycles and a method based on displacement forpoint agents. Finally, collision avoidance is incorporated withthe displacement-based controller. For this case, agents keepformation without colliding within formation and with staticobstacles in the workspace. The proposed controllers are verifiedthrough simulations in MATLAB. / Användningen av autonoma markfordon har ökat kraftigt de senaste åren. Således är det viktigt att få en bättre förståelse för grunderna i deras kommunikationsnätverk. I detta projekt studeras tre essentiella områden: projektilspårning, formationshållning och undvikning av kollisioner. Först och främst implementeras projektilspårning för en enhjuling där den styrs mot en önskad projektilbana. Därefter betraktas formationshållning genom två metoder: Den första metoden handlar om virtuella strukturer med en förutbestämd bana för enhjulingar. Den andra metoden baseras på en förskjutningsbaserad regulator. Slutligen införs undvikning av kollisioner tillsammans med den förskjutningsbaserade regulatorn för att uppnå ett kollisionsundvikande robotsystem. Samtliga objektiv inom de tre områdena nås med varierande precision. / Kandidatexjobb i elektroteknik 2020, KTH, Stockholm

International Telemetering Conference Proceedings / October 26-29, 1992 / Town and Country Hotel and Convention Center, San Diego, California / New tracking/control system requirements demand that the present DFCS/GRDCUS/MTACS data link bit rate be increased. A possible method for achieving this increase is to select two additional 31-bit chip code patterns that are orthogonal to the present chip codes, and to each other. This method will not require any more bandwidth than the present 10 MHZ used. This method suggest that each of the four chip code patterns are assigned a two bit value ie: 00, 01, 10, 11. At present, the two correlated chip codes represent data in a pulse position method. No data is contained in which of the two chip codes actually correlated. This new method suggest each of the four chip code patterns will still perform the pulse position modulation and provide two additional bits of data. These additional two bits of data will up the data rate of the link by 100 percent.

Este trabalho trata da coordenação de robôs heterogêneos que consiste em um robô helicóptero e em múltiplos robôs móveis com rodas, de modo que estes sigam um líder. Para atingirmos este objetivo, neste trabalho desenvolve-se a estimação da atitude e posição de um robô utilizando filtros robustos. Os filros realizam a fusão dos sinais de uma unidade de medida inercial de baixo custo e de um receptor GPS (Global Positioning System) considerando um modelo de corpo rígido formulado em termos de quatérnios. Resultados experimentais são apresentados baseados em um estudo comparativo entre os filtros robustos e o filtro de Kalman. Desenvolve-se o controle de um robô móvel com rodas deslizantes e de um robô helicóptero. Para realizar o controle robusto utilzia-se um regulador robusto recursivo. Simulaçõoes do robô móvel com rodas deslizantes e do robô helicóptero são apresentadas utilizando os parâmetros de um robô móvel Pioneer 3AT e de um robô helicóptero RMAX. Desenvolve-se também um mini robô helicóptero e uma base de movimento para realização de testes de controle do mini robô helicóptero constiste de um mini helimodelo e de um piloto automático baseado em um microprocessador com conectividade Wi-Fi, uma unidade de medida inercial e uma placa de controle de servos motores. E por fim, desenvolve-se a coordenação de robôs heterogêneos de modo que estes sigam um líder. Para isto é utilziado um controlador descentralizado e cooperativo cuja finalidade é gerar trajetórias de referência para que os robôs heterogênos se movimentem em formação rígida. / This research deals with the coordination of the heterogeneous robots, consisting of a robotic helicopter and multiple uheeled mobile robots, to achieve this aim this work develops the estimation of attitude, heading and positions of a robot based on robust filters. The filters perform the fusion of the signals of a low-cost inertial measurement unit and a GPS (Global Positioning System) receiver considering a rigid body model formulated in terms of quaternions. Experimental results are presented based on a comparative study of the robust filters and Kalman filter. It develops a robust control scheme of a ski-steering mobile robot and a robotic helicopter. The robust control is performed through a the robust recursive regulator. Simulations of the skid-steering mobile robot and a robotic helicopter are presented using the parameters of a Pioneer 3AT and a robotic helicopter RMAX. It also develops a mini robotic helicopter and a motion base to perform control test of a mini robotic helicopter. The mini robotic helicopter consists of a mini helicopter TREX 450 XL and an autopilot based on a microprocessor with Wi-Fi, an inertial measurement unit a servo control board. To finish, it develops the coordination of the heterogeneous robots in order to perform a leader strategy based on the concept of rigid formation.

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

Cette thèse traite de la question du contrôle du mouvement d'engins non-holonomes et sous-actionnés évoluant de manière coordonnée et autonome. Les différentes approches considérées sont le suivi de trajectoire (Trajectory Tracking TT) et le suivi de chemin (path following PF). Une nouvelle méthode de contrôle est proposée. Dénommée Path-Tracking (PT), elle permet de cumuler les avantages de chacune des deux précédentes méthodes, permettant de cumuler la souplesse de la convergence induite par le suivi de chemin avec le respect des contraintes temporelles du suivi de trajectoire. L'étude et la réalisation de la commande démarre avec l'étude du cas du robot nonholonome de type Unicycle' et se base sur les principes de Lyapunov' et de Backstepping'. Ces premiers résultats sont ensuite étendus au cas d'un véhicule sous-marin sous-actionné de type AUV (Autonomous Underwater Vehicle'), en analysant les similarités cinématiques entre ces deux types de véhicules. De plus, il est montré la nécessité de prendre en compte les propriétés dynamiques du système de type AUV, et la condition de Stern dominancy' est établie de façon à garantir que le problème est bien posé et ainsi que la commande soit aisément calculable. Dans la cas d'un système marin sur-actionné, qui peut ainsi effectuer des tâches de navigation au long cours et de positionnement désiré (Station keeping'), une commande hybride est proposée. Enfin, la question du contrôle coordonné d'une formation d'engins marin est abordée. Les colutions de commande pour les taches de suivi de chemin coordonné (coordinated path following') et de coordinated path tracking' sont proposées. Les principes du leader-follower' et la méthode des structures virtuelles sont ainsi traitées dans un cadre de contrôle centralisé, et le cas décentralisé est traité en utilisant certains principes de théorie des graphes. / In this dissertation, the problems of motion control of underactuated autonomous vehicles are addressed,namely trajectory tracking (TT), path following (PF), and novelly proposed path tracking whichblending the PF and TT together in order to achieve smooth spatial convergence and tight temporalperformance as well.The control design is firstly started from the benchmark case of nonholonomic unicycle-type vehicles,where the Lyapunov-based design and backstepping technique are employed, and then it is extendedto the underactuated AUVs based on the similarity between the control inputs of two kinds of vehicles.Moreover, dealing with acceleration of side-slip angle is highlighted and stern-dominant property of AUVsis standing out in order to achieve well-posed control computation. Transitions of motion control fromunderactuated to fully actuated AUVs are also proposed.Finally, coordinated formation control of multiple autonomous vehicles are addressed in two-folds,including coordinated paths following and coordinated paths tracking, based on leader-follower andvirtual structure method respectively under the centralized control framework, and then solved underdecentralized control framework by resorting to algebraic graph theory.

Neste mestrado propõe-se um estudo sobre o controle automático de sistemas dinâmicos para o problema de coordenação de robôs móveis. Os movimentos coordenados serão realizados em função de um líder e qualquer robô da formação pode assumir a liderança de maneira aleatória. Os robôs trocam informação através de um grafo direcionado (dígrafo) de comunicação, definido a-priori e, movimentos estáveis são gerados através de uma lei de controle descentralizada baseada nas coordenadas dos robôs. Além disso, as equações dinâmicas não lineares dos robôs são descritas na forma de espaço de estado sendo os parâmetros das matrizes dependentes da velocidade angular das rodas. Esta representação, conhecida como Quase Linear a Parâmetros Variantes (Quase-LPV), é utilizada no projeto de controle H \'INFINITO\' não linear para sistemas dinâmicos. Para garantir a estabilidade da formação quando há alternância de líder ou remoção de robôs, foi feito o controle robusto e controle tolerante a falhas para um grupo de robôs móveis com rodas (RMRs). O controle robusto é baseado em controle H \'INFINITO\' não linear via realimentação do estado e controle H \'INFINITO\' não linear via realimentação da saída. O controle tolerante a falhas é baseado em controle H \'INFINITO\' por realimentação da saída de sistemas lineares sujeitos a saltos Markovianos para garantir a estabilidade da formação quando um dos robôs é perdido durante o movimento coordenado. Resultados em simulação são apresentados para os controladores utilizados. / This dissertation proposes a study on the automatic control of dynamic systems to the problem of coordination of mobile robots. The coordinated motions are performed with the robots following a leader, and any robot of the formation can assume the leadership randomly. The robots exchange informations according to a pre-specified communication directed graph (digraph). Stable motions are generated by a decentralized control law based on the robots coordinates. In addition, the nonlinear dynamic equations of the robots are described in state-space form where the parameters matrices depend on the angular velocities of the wheels. This representation, known as Quasi-Linear Parameter Varying (Quasi-LPV), is useful for control designs based on nonlinear H \'INFINITE\' approaches. To ensure the stability formation when there is alternation of leader or one of the robots is removed, we made a robust control and fault tolerant control for a group of wheeled mobile robots (WMRs). The robust approach is based on state feedback nonlinear H \'INFINITE\' control and output feedback nonlinear H \'INFINITE\' control. The fault tolerant approach is based on output feedback H \'INFINITE\' control of Markovian jump linear systems to ensure stability of the formation when one of the robots is lost during the coordinated motion. Results in simulation are presented for the controllers used.

Orientador: Prof. Dr. Luiz de Siqueira Martins Filho / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia Mecânica, 2014.

Neste mestrado propõe-se um estudo sobre o controle automático de sistemas dinâmicos para o problema de coordenação de robôs móveis. Os movimentos coordenados serão realizados em função de um líder e qualquer robô da formação pode assumir a liderança de maneira aleatória. Os robôs trocam informação através de um grafo direcionado (dígrafo) de comunicação, definido a-priori e, movimentos estáveis são gerados através de uma lei de controle descentralizada baseada nas coordenadas dos robôs. Além disso, as equações dinâmicas não lineares dos robôs são descritas na forma de espaço de estado sendo os parâmetros das matrizes dependentes da velocidade angular das rodas. Esta representação, conhecida como Quase Linear a Parâmetros Variantes (Quase-LPV), é utilizada no projeto de controle H \'INFINITO\' não linear para sistemas dinâmicos. Para garantir a estabilidade da formação quando há alternância de líder ou remoção de robôs, foi feito o controle robusto e controle tolerante a falhas para um grupo de robôs móveis com rodas (RMRs). O controle robusto é baseado em controle H \'INFINITO\' não linear via realimentação do estado e controle H \'INFINITO\' não linear via realimentação da saída. O controle tolerante a falhas é baseado em controle H \'INFINITO\' por realimentação da saída de sistemas lineares sujeitos a saltos Markovianos para garantir a estabilidade da formação quando um dos robôs é perdido durante o movimento coordenado. Resultados em simulação são apresentados para os controladores utilizados. / This dissertation proposes a study on the automatic control of dynamic systems to the problem of coordination of mobile robots. The coordinated motions are performed with the robots following a leader, and any robot of the formation can assume the leadership randomly. The robots exchange informations according to a pre-specified communication directed graph (digraph). Stable motions are generated by a decentralized control law based on the robots coordinates. In addition, the nonlinear dynamic equations of the robots are described in state-space form where the parameters matrices depend on the angular velocities of the wheels. This representation, known as Quasi-Linear Parameter Varying (Quasi-LPV), is useful for control designs based on nonlinear H \'INFINITE\' approaches. To ensure the stability formation when there is alternation of leader or one of the robots is removed, we made a robust control and fault tolerant control for a group of wheeled mobile robots (WMRs). The robust approach is based on state feedback nonlinear H \'INFINITE\' control and output feedback nonlinear H \'INFINITE\' control. The fault tolerant approach is based on output feedback H \'INFINITE\' control of Markovian jump linear systems to ensure stability of the formation when one of the robots is lost during the coordinated motion. Results in simulation are presented for the controllers used.

Multiagent coordination problems arise in a variety of applications, from satellite constellations and formation flight, to air traffic control and unmanned vehicle teams. We investigate the coordination of mobile agents using two kinds of approaches. In the first, which takes its inspiration from fluid dynamics and algebraic topology, control authority is split between mobile agents and a network of static infrastructure nodes - like wireless base stations or air traffic control towers - and controllers are developed that distribute their computation throughout this network. In the second, we look at networks of interconnected mechanical systems, and develop novel optimal control algorithms, which involve the computation of optimal deformations of time- and output- spaces, to achieve approximate formation tracking. Finally, we investigate algorithms that optimize these controllers to meet subjective criteria of humans.

<p>This thesis consists of four independent papers concerningthe control of mobile robots in the context of obstacleavoidance and formation keeping.</p><p>The first paper describes a new theoreticallyv erifiableapproach to obstacle avoidance. It merges the ideas of twoprevious methods, with complementaryprop erties, byusing acombined control Lyapunov function (CLF) and model predictivecontrol (MPC) framework.</p><p>The second paper investigates the problem of moving a fixedformation of vehicles through a partiallykno wn environmentwith obstacles. Using an input to state (ISS) formulation theconcept of configuration space obstacles is generalized toleader follower formations. This generalization then makes itpossible to convert the problem into a standard single vehicleobstacle avoidance problem, such as the one considered in thefirst paper. The properties of goal convergence and safetyth uscarries over to the formation obstacle avoidance case.</p><p>In the third paper, coordination along trajectories of anonhomogenuos set of vehicles is considered. Byusing a controlLyapunov function approach, properties such as boundedformation error and finite completion time is shown.</p><p>Finally, the fourth paper applies a generalized version ofthe control in the third paper to translate,rotate and expanda formation. It is furthermore shown how a partial decouplingof formation keeping and formation mission can be achieved. Theapproach is then applied to a scenario of underwater vehiclesclimbing gradients in search for specific thermal/biologicalregions of interest. The sensor data fusion problem fordifferent formation configurations is investigated and anoptimal formation geometryis proposed.</p><p><b>Keywords:</b>Mobile Robots, Robot Control, ObstacleAvoidance, Multirobot System, Formation Control, NavigationFunction, Lyapunov Function, Model Predictive Control, RecedingHorizon Control, Gradient Climbing, Gradient Estimation.</p>