Cette étude se focalise principalement sur la modélisation et l’amélioration d’un accumulateur industriel de bande. Le premier chapitre présente la modélisation non-linéaire, puis la linéarisation autour d'un point de fonctionnement, d’un accumulateur industriel comportant un chariot pneumatique ou motorisé. Cette modélisation complète prend en compte les non-linéarités des différents types d’actionneurs du chariot. Les paramètres mécaniques les plus influents sur les performances de ces accumulateurs sont mis en évidence, puis les stratégies de commandes industrielles classiques sont testées sur ces accumulateurs. Le second chapitre présente l’optimisation des performances de l’accumulateur. Des améliorations de la commande sont réalisées : prise en compte de la robustesse, optimisations multi-objectifs, nouvelles structures de commandes. Ces améliorations montrent un net gain des performances concernant la tension de bande à la sortie de l'accumulateur. De nouvelles structures d’accumulateurs incluant un danseur sont proposées, améliorant fortement les performances. Une comparaison des performances des différents accumulateurs est présentée. Le dernier chapitre présente l’étude du frottement bande textile/rouleau. Le comportement au frottement de bandes textiles glissant sur un rouleau est identifié. L'évolution du coefficient de frottement est déterminée expérimentalement pour différents paramètres et types de bandes. Suite à ces mesures, un modèle de bande défilant sur un rouleau, incluant coefficient de frottement et perte d’adhérence est proposé et montre l’influence du coefficient de frottement sur la réponse du système à une variation de vitesse de bande. / This study focuses mainly on modeling and optimization of industrial web accumulators. The chapter one presents the nonlinear model of an industrial accumulator including a pneumatic actuated or a motorized carriage. The nonlinear model is then linearized around a working point. This model takes into account nonlinearities of both carriage actuators. The most influent mechanical parameters on the accumulator performances are highlighted and then, classical industrial control strategies are tested on the modeled accumulators. The chapter two concerns the accumulator performances optimization. Firstly, controllers are improved by taking into account the robustness against parameter variations, by using multi-objective controllers optimization or by using new control strategies. All these improvements show drastic performances gain. New accumulator structures including a dancer roll are proposed and improve also the accumulator performances. A performances comparison of the entire presented accumulator is presented at the end of this chapter. The last chapter presents the study of the friction between textile fabric and roll. The friction behavior of a web sliding on a roll is identified. The friction coefficient evolution is experimentally determined for different experimental parameters and kind of webs. These measures have permitted to build a model of a web sliding on a roll. This model, including the friction coefficient and the adherence loss between web and roll highlights the response of the web/roll system against web velocity variation.

A manipulação de materiais é uma das tarefas em que comumente empregam-se robôs para substituir o trabalho humano, dadas algumas vantagens como: maior precisão na manipulação de cargas e maior velocidade de execução da tarefa, bem como por aumentar a segurança do operador. Apesar dessas vantagens, os dispositivos robóticos são largamente empregados apenas em situações em que velocidade e precisão são indispensáveis, em outros casos, os equipamentos convencionais (como talhas, gruas e macacos hidráulicos) e os dispositivos específicos (aqueles fazem uso de molas e contrapesos), vêm sendo utilizados nas tarefas cotidianas, principalmente pelo fato de, entre outros, serem menos dispendiosos. Comparando-se estas duas soluções disponíveis, tem-se que os equipamentos tradicionais, apesar de sua simplicidade e versatilidade de movimentação, apresentam limitações quando são exigidas precisão e eficiência, enquanto os dispositivos robóticos apresentam alta complexidade tanto no projeto quanto na operação, representando uma solução cara e com movimentação restrita pela programação. Neste contexto, o presente trabalho tem por objetivo estudar e propor uma solução intermediária entre a solução convencional e a robótica. O foco do estudo é o projeto de um dispositivo simplificado, que faz uso de molas e de um sistema de alavanca para manipular cargas. Um estudo preliminar desse mecanismo mostrou imperfeições quanto à força de contrabalanceamento. Com o intuito de corrigir esse erro foi usado um sistema de controle, que é constituído por um motor elétrico, um mecanismo de correção, sensores e um módulo controlador. O dispositivo proposto apresenta um controle simplificado, vez que a movimentação é feita exclusivamente pelo operador, possibilitando assim que o dispositivo apresente um baixo consumo de energia. Um protótipo é desenvolvido e os testes demonstraram a eficácia da solução. / The material handling is one task in which robot is commonly employed to replace the human work because it has some advantages such as, higher precision in the handling and higher speed of the task, and to increase operator safety. Despite these advantages, the robotic device is most employed only in situation that speed and precision are essential; in other cases, the conventional equipments (such as hydraulic jacks, cranes and pulley systems) and the specific device (which use springs and counterweight), have been used in daily tasks mainly because of they are less expensive. Comparing these two solutions, it is possible to say that the conventional devices, despite its simplicity and guidance, have limitations when the task requires precision and speed, while the robotic solution has higher complexity in both design and in operation, representing an expensive solution with a programming that restrict the movement. In this context, the present work has the objective the study and development of an intermediate solution between the conventional solution and the robotic device. The proposed study is based on a simplified device, which uses springs and a lever system to handle material. A preliminary study on this mechanism shows imperfections in balance force. In order to correct this error, a control system is used. The control system is constituted by an electric motor, a correcting mechanism, sensors and a controller. The proposed device presents simple control because movements are responsibility of the human operator moreover presents low power consumption, due to the use of springs. A prototype is developed and tests demonstrate the effectiveness of the solution.

This thesis gives different views on the modeling and simulation of physical systems, especially together with embedded systems, forming mechatronic systems. The main considered application domain is automotive. One motivation behind the work is to find suitable representations of physical systems to be used in an architectural description language for automotive embedded systems, EAST-ADL2, which is implemented as a UML2 profile, and uses concepts from both UML and SysML. As a part of the thesis, several languages and tools are investigated, including bond graphs, MATLAB/Simulink, Ptolemy II, Modelica, MATLAB/Simscape and SysML. For SysML, the modeling of continuous-time systems and how it relates to MATLAB/Simulink and Modelica is evaluated. A case study of an electric power assisted steering is modeled to show the differences, the similarities and the usage of the above mentioned languages and tools. To be able to classify the tools and languages, five realization levels were developed: Physical modeling models Constraint models Continuous causal models Discretized models Discretized models with solver and platform implementation By using these realization levels, models, tools and modeling languages can be classified, and transformations between them can be set up and analyzed. As a result, a method to describe the simulation behavior of a MATLAB/Simulink model has been developed using SysML activity diagrams as an approach to achieve integrated system models. Another result is an evaluation of the parametric diagrams of SysML for continuous-time modeling, which shows that they do not enable “physical modeling”, i.e. modeling the topology of the system and getting the underlying equations out of this topology. By including physical ports and physical connectors to SysML internal block diagrams, this could be solved. The comparison also shows many similarities between the languages. The results led to a more detailed investigation on conjugate variables, such as force and velocity, and electric current and voltage, and how these are treated in various languages. The thesis also includes two industrial case studies: one of a twin-screw compressor, and one of a simulation environment for automotive fuel-cell systems. Conclusions are drawn from these models, referring to the realization levels. / QC 20100810

Robotics is an emerging field, and it is also affecting several other fields. Design of robotic platforms gains more importance since the focus and aim of the robotics research broadens widely and the variety of the users is significant. This work aims to present the design of a modular mobile robotic platform, which should be simple, easy to build and easy to use. The concept of modularity, usage of off-the shelf components and utilizing a PC platform, are addressed in this work. As a result of this work, a conceptual design is presented, and a prototype is built to highlight some important aspects of the conceptual design.

This thesis presents a technique termed Blended Shared Control, whereby a human operator's commands are merged with the commands of an electronic agent in real time to control a manipulator. A four degree-of-freedom hydraulic excavator is used as an application example, and two types of models are presented: a fully dynamic model incorporating the actuator and linkage systems suitable for high-fidelity user studies, and a reduced-order velocity-constrained kinematic model amenable for real-time optimization. Intended operator tasks are estimated with a recursive algorithm; the task is optimized in real time; and a command perturbation is computed which, when summed with the operator command, results in a lower task completion time. Experimental results compare Blended Shared Control to other types of controllers including manual control and haptic feedback. Trials indicate that Blended Shared Control decreases task completion time when compared to manual operation.

M. Tech. Electrical Engineering. / The hypothesis states that a closed loop control system could be applied to a mechatronic system consisting of a mechanical device(s) to be fitted onto the user, and other relevant periphery mechanical devices, appropriately actuated to provide powered movement to assist the wheelchair-bound individual securely attain a standing position.The premise upon which the hypothesis was to be tested relates to the control system's ability to facilitate the upward movement proposed and its degree of stability when simulating the system, thus re-creating the anticipated functionality.

Mining is one of the main economic sectors in South Africa. Mining activity contains hazards such collapsing of structures, presence of dangerous gases, accidental explosions and fires. Even though most of these hazards are identified and minimized sometimes accidents occur. These accidents lead to human injuries, direct fatalities and fatalities resulting from delays in victims getting medical attention as a result of delays in search and rescue missions. The rescue missions in underground mines present challenges where rescuers are not sure which locations are victims in, what the area conditions like in the rescue path. A quad rotor unmanned aerial vehicle (UAV) for search and rescue missions is presented. The UAV is controlled from a remote location over Wi-Fi. The communication allows data relay to the ground control station. The communication system is tested on the university’s Wi-Fi network. The UAV also contains a vision system that contains a human detection algorithm to give an indication of human presence to rescuers. The human detection system is based on Haar- Cascade classifiers. The model developed was found to have a false alarm rate of 5×10-3% after training. The model was further tested on streaming data and the overall average positive human detection was found to be 97 %. In the same tests overall false average detection was found to be 2.5 %. The video feed is streamed from the UAV to the ground station (GS) and the flight control instructions are sent to the UAV from the GS via Wi-Fi. / Thesis (M.Sc.Eng)-University of KwaZulu-Natal, Durban, 2013.

No description available.

This thesis describes a system which is able to track and imitate human motion. The system is divided into two major parts: computer vision system and robot arm motion control system. Through the use of two real-time video cameras, computer vision system identifies the moving object depending on the colour features, as the object colour is matched within the colour range in the current image frame, a method that employs two vectors is used to calculate the coordinates of the object. After the object is detected and tracked coordinates are saved to a pre-establish database in the purpose of further data processing, a mathematical algorithm is performed to the data in order to give a better robotic motion control. Robot arm manipulator responds with a move within its workspace which corresponds to a consequential human-type motion. Experimental outcomes have shown that the system is reliable and can successfully imitate a human hand motion in most cases.

The quality of Machine Translation (MT) can often be poor due to it appearing incoherent and lacking in fluency. These problems consist of word ordering, awkward use of words and grammar, and translating text too literally. However we should not consider translations such as these failures until we have done our best to enhance their quality, or more simply, their fluency. In the same way various processes can be applied to touch up a photograph, various processes can also be applied to touch up a translation. This research outlines the improvement of MT quality through the application of Fluency Enhancement (FE), which is a process we have created that reforms and evaluates text to enhance its fluency. We have tested our FE process on our own MT system which operates on what we call the SAM fundamentals, which are as follows: Simplicity - to be simple in design in order to be portable across different languages pairs, Adaptability - to compensate for the evolution of language, and Multiplicity - to determine a final set of translations from as many candidate translations as possible. Based on our research, the SAM fundamentals are the key to developing a successful MT system, and are what have piloted the success of our FE process.