[pt] Controle de estabilidade é uma técnica aplicada para aumentar a segurança em veículos automotivos. Ele compreende não apenas controle de guinada como controle de rolagem, principalmente em veículos altos como caminhões. Uma tendência na indústria automobilística já consagrada em sistemas robóticos de exploração são os veículos elétricos que possuem motores elétricos independentes em cada roda. Sua característica de não emitir qualquer poluente os torna ambientalmente atraentes e, devido à forma de atuação, tendem a ser mecanicamente menos complexos. Os controles de estabilidade atuais visam prevenir que o veículo chegue a uma situação de instabilidade. No entanto, veículos em alta velocidade que encontrem obstáculos nos terrenos podem perder o contato com o solo. Nessa situação, os controles de estabilidade atuais nada podem fazer para garantir um retorno seguro para o terreno. Este trabalho apresenta um algoritmo de detecção de descolamento da roda para identificação do início da fase balística e consequente determinação da ação necessária para aumentar as chances de um retorno seguro ao chão. São usados apenas sensores de corrente e velocidade dos motores para a detecção. O controle por roda de reação é aplicado ao veículo para estabilização durante a fase balística. O algoritmo também é capaz de estimar o torque externo aplicado sobre a roda usando os mesmo sensores utilizados para o controle de torque dos motores, tornando a técnica uma ferramenta sem custos adicionais ao sistema. Os algoritmos de controle e detecção apresentados foram testados experimentalmente e em um simulador desenvolvido para a pesquisa usando o modelo de um veículo robótico de sessenta quilogramas com quatro rodas independentes atuadas por meio de motores elétricos de corrente contínua. Os resultados obtidos mostram o potencial da técnica para futuras aplicações. / [en] Stability control is a known algorithm used to increase safety in passenger vehicles. It comprises not only yaw control but rollover as well, mainly in vehicles with high centers of gravity. Another already established trend in the automobile industry are electric vehicles with independently driven wheels. Its zero-emitting qualities have made them environmentally attractive and, due to their drivetrain design, they tend to be mechanically less complex. Stability controls used nowadays work to prevent the vehicle from reaching unstable situations. Nonetheless, high speed vehicles hitting obstacles may lose contact with the ground. In these situations, none of the existing stability controls can guarantee safe landing during ballistic motion. This work presents an algorithm for flying wheel detection to help identify ballistic motion tendencies and therefore determine the appropriate action to increase the odds of a safe landing. Current sensors and encoders are used by the algorithm. A reaction wheel based control is proposed to stabilize and adjust the pitch angle during ballistic motion and set up the vehicle to a better position to return to land. The flying wheel detection algorithm can also estimate external torques acting on the wheel using the same sensors already installed in the motor for current control, making it a costless technique. The detection algorithm and pitch control algorithm presented were tested experimentally and in a simulator developed for the research. The results show the potential of the algorithms presented for future implementations.

Η διπλωματική αυτή εργασία έχει ως αντικείμενο μελέτης εφαρμογές / διεργασίες στα ρομποτικά σμήνη. Οι εφαρμογές / διεργασίες που εξετάζονται είναι η καλυψιμότητα χώρου, η διατήρηση συνδεσιμότητας και τα παιχνίδια κυνηγού - κυνηγούμενου. Συγκεκριμένα, εξετάζονται δύο μέθοδοι καλυψιμότητας χώρου: κίνηση προς το κεντροειδές και κίνηση προς τη βάθμωση. Εισάγονται οι επικοινωνιακοί περιορισμοί και προτείνονται περιορισμοί κίνησης που εξασφαλίζουν διατήρηση N-hop συνδεσιμότητας, οι οποίοι έπειτα προσαρμόζονται στην καλυψιμότητα χώρου. Αναλύονται δύο τακτικές κυνηγού: οι έμμεσοι κυνηγοί και η τακτική περικύκλωσης, και προτείνονται δύο τακτικές για τους κυνηγούμενους. Η πρώτη αποτελεί μία παθητική αποφυγή των κυνηγών, ενώ η δεύτερη μια πιο δυναμική συνεργατική τακτική. Τέλος, προσομοιώσεις συνοδεύουν όλα τα παραπάνω μέρη, που επιβεβαιώνουν την αποτελεσματικότητά τους και προσφέρουν σύγκριση των διάφορων μεθόδων για την κάθε εφαρμογή. / This thesis addresses applications / tasks of robotic swarms. The applications / tasks presented are the area coverage, communication maintenance and pursuer - evasion games. Two methods for area coverage are examined; centroid and gradient movement. Communication constraints are considered and movement constraints are proposed, such that the swarm's N-hop connectivity is retained. Then the contraints are adapted for the area coverage problem. After that, two pursuing tactics are examined; the indirect pursuers and the blanket movement, and two evader tactics are proposed. The first is a passive pursuers avoidance, while the second is a more dynamic collaborative tactic. Finally, simulations accompanying the above sections, confirm the efficiency and offer a comparison between the different methods in each application.

This thesis covers the topic of controlling RC servos and constructions of robotic vehicles. The goal is to propose a model of robotic vehicle with RC components and other off the shelf components, 3D printing and demonstrate its capabilities. In the thesis, a mobile robot platform was proposed. It uses a single-board computer together with readily available parts and does not require complicated assembly. An optimization algorithm was used for the design of rack and pinion steering. The result of the thesis is the implementation of a robotic vehicle.