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No description available.

No description available.

No description available.

<p> Several algorithms for multi-robot coordination assume that the communication network of a team of mobile robots is connected, so that information can be exchanged between any two robots in the team. The network topology is often state-dependent, and thus the robots may move in a way that causes the network to become disconnected. This dissertation proposes continuous time control laws that preserve the connectivity for both undirected and directed mobile robot networks, which can be used along with additional task-dependent control actions. An additional aim of the dissertation is to provide control algorithms to achieve multi-robot coordination methods using vision-based feedback. Feedback control laws are presented that achieve tracking of desired relative positions between a pair of non-holonomic mobile robots using relative position measurements only. Issues pertaining to vision-based implementation of the connectivity control laws are discussed, and solutions are presented.</p>

<p> One of the most important traits of a robotic manipulator is its work envelope, the space in which the robot can position its end effector. Parallel manipulators, while generally faster, are restricted by smaller work envelopes. As such, understanding the parameters defining a physical robot's work envelope is essential to the optimal design, selection, and use of robotic parallel manipulators. </p><p> A Linear Delta Robot (LDR) is a type of parallel manipulator in which three prismatic joints move separate arms which connect to a single triangular end plate. In this study, general inverse kinematics were derived for a linear delta robot. These kinematics were then used to determine the reachable points within a plane in the robot's work envelope, incorporating the physical constraints imposed by a real robot. After simulating several robots of varying parameters, a linear regression was performed in order to relate the robot's physical parameters to the inscribed radius of the area reachable in a plane of the LDR's work envelope. Finally, a physical robot was constructed and used as a reality check to confirm the kinematics and inscribed radius. </p><p> This study demonstrates the relationship between the LDR's physical dimensions and the inscribed radius of its work envelope. Building a physical robot allowed confirmation of the resulting equation, validating an accurate representation of the LDR's physical constraints. By doing so, the resulting equation provides a powerful tool for correctly sizing a LDR based on a desired work envelope. </p>

Wheel-legged hybrid robots are known to be extremely capable in negotiating different types of terrain as they combine the efficiency of conventional wheeled platforms and the rough terrain capabilities of legged platforms. The Micro-Hydraulic Toolkit (MHT), developed by Defence Research and Development Canada at the Suffield Research Centre, is one such quadruped hybrid robot. Previously, a velocity-level closed loop inverse kinematics controller had been developed and tested in simulation on a detailed physics-based model of the MHT in LMS Virtual.Lab Motion (VLM). The controller was employed to generate a variety of posture reconfiguration and navigation maneuvers in simulation, such as achieving minimum or maximum chassis height at specific wheel separations, orienting the chassis to a desired pitch angle, or negotiating simulated rough terrain. In this thesis, the aforementioned inverse kinematics controller was improved upon, optimized and adapted to function on the physical MHT vehicle, located in Suffield, Canada. In addition, as a first step towards identifying the deficiencies of the VLM model and, ultimately, validating the model, actuator performance was measured for open loop step and ramp inputs and compared to the simulation results. With the controller implemented on MHT, a subset of the posture reconfiguration and navigation maneuvers previously performed in simulation were tested on the MHT and the robot performance was evaluated. Furthermore, a parametrized algorithm for statically stable step-climbing was developed and successfully verified on the MHT for different step heights. / Les robots à locomotion articulée sur roues ont la capacité de circuler sur différents types de terrain avec aise, puisqu'ils combinent l'efficacité énergétique des véhicules conventionnels munis de roues et la capacité de se déplacer sur une surface irrégulière des systèmes équipés de pattes. Le Micro-Hydraulic Toolkit (MHT) est un robot quadrupède développé par Recherche et développement pour la défense Canada au centre de recherches de Suffield qui se situe dans cette catégorie. Cette machine est dotée de quatre pattes articulées qui se terminent chacune par une roue. Précédemment, un mécanisme de contrôle cinématique inverse à boucle fermée a été développé et testé en simulation sur un modèle détaillé du MHT à l'aide du logiciel LMS Virtual.Lab Motion (VLM). L'objectif de ce contrôleur était de générer des commandes cinématiques aux joints du robot afin de reconfigurer la posture de celui-ci et d'effectuer des manœuvres de navigations. Dans cette thèse, le contrôleur cinématique inverse est adapté et optimisé pour fonctionner avec le robot MHT. Afin d'identifier les erreurs du modèle du robot sur VLM et de contribuer à la révision du modèle, des expériences ont été effectuées à boucles ouvertes sur les joints du robot en utilisant des commandes en échelon et en rampe. Les résultats de ces tests ont par la suite été comparés avec ceux obtenus en simulation. Puis, après que le contrôleur fut implémenté sur MHT, une séquence de reconfigurations de posture précédemment testée en simulation a été testée sur le robot, et la performance de celui-ci a été évaluée. Finalement, un algorithme paramétré visant à permettre à MHT de monter une marche a été développé et testé avec succès sur le robot avec différentes hauteurs de marches.

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This work investigates the automation of assembly cells and the need to incorporate sensor-guided decision techniques. The experience of industry in this area is examined by observing a real cell on the shop floor. From the collected data conclusions point to an alternative error interpretation which describes the successful completion rather than an enumeration of errors. A methodology for the description of the process in robotic assembly is developed. The constituent phases in handling components are identified as Feeding, Transport and Mating. Each phase has well defined characteristic properties which can be determined using appropriate sensing mechanisms. The mating phase is given special attention by proposing the method of information Spaces as a suitable frame work for sensor fusion and context directed interpretation. Thus the successful progress is described regarding any deviations as errors. They in turn can be interpreted in the context in which they were encountered and recovery is accomplished in the demonstration cell by operator taught routines. Where error repetition occurs, a simple look-up technique suffices to remove the need for another operator intervention. The required data structures and the implementation of the experimental cell are discussed. It is concluded from the results that the principle of knowledge-based assembly control exhibits an intelligent behaviour which contributes to an increase in the cell productivity. This method addresses only a part of the overall problem of assembly automation, but it has a central place in the system and could be extended to the complete system.

No description available.