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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

The Control of Multiple Actuators using Single IEHEC Pump/Motor

Bekele, Teshale, Åman, Rafael, Handroos, Heikki 28 April 2016 (has links) (PDF)
The awareness and concern of our environment together with legislation have set more and more tightening demands for energy efficiency of non-road mobile machinery(NRMM). Integrated electro- hydraulic energy converter (IEHEC) has been developed in Lappeenranta University of Technology (LUT) /1/. The elimination of resistance flow, and the recuperation of energy makes it very efficient alternative. The difficulties of IEHEC machine to step to the market has been the requirement of one IEHEC machine per one actuator. The idea is to switch IEHEC between two actuators of log crane using fast on/off valves. The control system architecture is introduced. The system has been simulated in co-simulation using Simulink/Mevea. The simulated responses of pumpcontrolled system is compared to the responses of the conventional valve-controlled system.
2

On Discretization of Sliding Mode Control Systems

Wang, Bin, s3115026@student.rmit.edu.au January 2008 (has links)
Sliding mode control (SMC) has been successfully applied to many practical control problems due to its attractive features such as invariance to matched uncertainties. The characteristic feature of a continuous-time SMC system is that sliding mode occurs on a prescribed manifold, where switching control is employed to maintain the state on the surface. When a sliding mode is realized, the system exhibits some superior robustness properties with respect to external matched uncertainties. However, the realization of the ideal sliding mode requires switching with an infinite frequency. Control algorithms are now commonly implemented in digital electronics due to the increasingly affordable microprocessor hardware although the essential conceptual framework of the feedback design still remains to be in the continuous-time domain. Discrete sliding mode control has been extensively studied to address some basic questions associated with the sliding mode control of discrete-time systems with relatively low switching frequencies. However, the complex dynamical behaviours due to discretization in continuous-time SMC systems have not yet been fully explored. In this thesis, the discretization behaviours of SMC systems are investigated. In particular, one of the most frequently used discretization schemes for digital controller implementation, the zero-order-holder discretization, is studied. First, single-input SMC systems are discretized, stability and boundary conditions of the digitized SMC systems are derived. Furthermore, some inherent dynamical properties such as periodic phenomenon, of the discretized SMC systems are studied. We also explored the discretization behaviours of the disturbed SMC systems. Their steady-state behaviours are discussed using a symbolic dynamics approach under the constant and periodic matched uncertainties. Next, discretized high-order SMC systems and sliding mode based observers are explored using the same analysis method. At last, the thesis investigates discretization effects on the SMC systems with multiple inputs. Some conditions are first derived for ensuring the
3

Vivid Agents: How They Deliberate, How they React, How They Are Verified

Wagner, Gerd 12 July 2019 (has links)
We propose a model of an agent which is both logical and operational. Our model of vivid agents takes into account that agents need not only the ability to draw inferences but also to update their current knowledge state, to represent and to perform (and to simulate the execution of) actions in order to generate and exe- cute plans, and to react and interact in response to perception and communication events. We illustrate our formalization of this basic functionality of an agent by means of examples. We also show how our model fits into the transition system semantics of concurrent reactive systems by identifying the five basic transitions of vivid agent systems: perception, reaction, planning, action, and replanning.
4

The Control of Multiple Actuators using Single IEHEC Pump/Motor

Bekele, Teshale, Åman, Rafael, Handroos, Heikki January 2016 (has links)
The awareness and concern of our environment together with legislation have set more and more tightening demands for energy efficiency of non-road mobile machinery(NRMM). Integrated electro- hydraulic energy converter (IEHEC) has been developed in Lappeenranta University of Technology (LUT) /1/. The elimination of resistance flow, and the recuperation of energy makes it very efficient alternative. The difficulties of IEHEC machine to step to the market has been the requirement of one IEHEC machine per one actuator. The idea is to switch IEHEC between two actuators of log crane using fast on/off valves. The control system architecture is introduced. The system has been simulated in co-simulation using Simulink/Mevea. The simulated responses of pumpcontrolled system is compared to the responses of the conventional valve-controlled system.
5

Digital pumps in speed-controlled systems – an energy study for a loader crane application

Kärnell, Samuel, Rankka, Amy, Dell`Amicio, Alessandro, Ericson, Liselott 25 June 2020 (has links)
Imagine a system with a pump driven by a speed-controlled electric motor. What and how much can be gained by using a pump with discretely variable displacement instead of a conventional fixed pump in such a system? This question is the focus in this paper, in which a simulation study based on a drive cycle for a loader crane is presented. The results indicate that the system efficiency from inverter input to pump output can increase by a few percentages. This might be considered small in relation to the increasing complexity that comes with discrete displacement. However, the results also show that a system with discrete displacement substantially reduces torque and cooling requirements on the electric motor. The required maximum torque can be reduced by 30 to 50 % and the motor can generate up to 40 % less heat since it can work in more efficient conditions. These potential benefits will be obtained with only a few discrete displacement settings available.
6

Influence des fautes transitoires sur la fiabilité d'un système contrôlé en réseau / Impact of transient faults on the reliability evaluation of a networked control system

Ghostine, Rony 12 June 2008 (has links)
Ce travail s'inscrit dans le cadre de l'évaluation de la sûreté de fonctionnement des systèmes commandés en réseau (SCR). La capacité des systèmes de commandes à compenser les effets de certaines défaillances de composants amène à redéfinir le concept de défaillances du système. La conséquence est que l'évaluation de la fiabilité prévisionnelle du système est dépendante de l'évaluation fonctionnelle et devient impossible avec les méthodes traditionnelles de la sûreté de fonctionnement. Pour surmonter ces difficultés, une approche basée sur la modélisation en vue de la simulation est proposée. Nous avons choisi les Réseaux d'activités stochastiques (SAN) largement connus dans la modélisation des protocoles de communication ainsi que dans les études de la sûreté de fonctionnement. Dans un premier temps, nous avons cherché à identifier l'incidence de deux types de défaillances fugitives : la perte d'un échantillon d'une part et le retard d'un échantillon dans la boucle de régulation d'autre part. Après, nous simulons le comportement en présence des deux types de perturbations simultanément, mettant en évidence des effets cumulatifs. Si on tient compte maintenant du fait que l'origine des pertes ou retards est due à la présence du réseau, il faut l'introduire dans le modèle. On introduit alors dans le modèle global du système la représentation SAN d'un réseau CAN et l'injection des défaillances dans celui-ci. La méthode de Monte Carlo est utilisée pour estimer les indicateurs de sûreté de fonctionnement et on montre l'influence de certains facteurs comme la charge du réseau par exemple. Nous avons proposé une méthode et les outils associés pour approcher cette évaluation par simulation et ainsi apporter une aide à la conception des systèmes satisfaisant à des exigences critiques sur certains paramètres de performance / Achieved work in this thesis deals with dependability evaluation of networked controlled system (NCS). The ability of control system to offset the effects of some components’ failure leads to redefine the concept of system failure. Consequently the reliability evaluation is dependent on functional parameters and becomes impossible with traditional dependability methods. This work aims at bringing a contribution relative to this aspect. To overcome these difficulties, an approach based on both modelling and simulation is proposed. We choose to work with stochastic activity network (SAN) widely used in modelling communication protocols as well as in dependability studies. First we sought to identify the incidence of two types of transient faults: loss of samples and delay within the control loop. Next we simulate the behaviour in the presence of two types of disturbances at the same time highlighting the cumulative effects. In fact the origin of the loss or delay information inside the control loop is due to the presence of the network, this aspect must be taken into account, that is why we introduce a new model representing the Controller Area Network (CAN) and injection of possible perturbations. Monte-Carlo method is used to estimate dependability parameters showing the influence of some factors such as network load for example. We have proposed a method and associated tools to approach this evaluation by simulation and thus provide assistance in designing systems to meet requirements on certain performance parameters
7

Finding missing people : Hur kan man effektivisera arbete med att söka efter försvunna personer?

Lugnegård, Mikael January 2015 (has links)
Finding missing people and obtaining an overview of complex emergencies is very demanding and requires costly resources. I have on a few occasions sought after my grandfather, who, when he got Alzheimer, liked to go for a stroll at night (!) when my grandmother was sleeping. Those kind of situations are very stressful, especially a cold winter night. During my first 25 years I was part of a dedicated outdoor culture with countless ski trips, mountain hikes, mountain bike trips and many hours in primarily Swedish nature. It happened on a few occasions that we came in contact with people who worked with rescue operations in this type of environment. It could be about hikers who strayed away or been injured in the inaccessible nature, lost skiers in the mountain massifs around Riksgränsen, berry pickers in the Västerbotten forests etc. There are many examples of this type of situations and it's reflections on these scenarios and similar current problem which is the basis for this project.   Every year, about 7000 people are reported missing in Sweden. Of these remains about 30-35 vanished. Globally, the figure is huge. Earthquakes, floods and other hit by natural occurs despite various preventive measures. There are many occasions where the search, reconnaissance and location of individuals as well as physical problems play a critical role, but where human capacity seldom is sufficient. Search party chains (organized by organisations like Missing People) requires significant human resources and costs precious time, police helicopter reconnaissance is economically very costly, not environmentally friendly and involves a significant margin of error. With these statements as background, I would look at the possibility of creating a thorough design solution that contributes to people in need can be located, provided security and helped significantly faster than today without requiring significant resources. With this as a backdrop, I wanted to create a concept that would contribute to that more people were found and could be saved. Through an extensive research of how a rescue operation is conducted, interviews with police and Missing People, as well as observations during actual operations, I identified a few main problem areas that my concept generation would center around. Together with my sponsor, we wanted to create something that can best be described as a robotic eagle with hyper vision, long flight time and a positive association for the victim. The result is Aetos (Greek for eagle). A modular drone-system with innovative features to handle with long flights and demanding rescue missions. Thanks to an aerodynamic shape and a remote-controlled system Aetos requires minimal resources to create overview and help in locating the missing person. We want to save lives, and it can Aetos that.
8

Červená královna / The Red Queen

Králík, Martin Unknown Date (has links)
Red Queen is a chess piece on the story of Alice in Wonderland, which is constantly running to hold it in place, because the world around it is constantly in motion. Therefore, it is a symbol of the theory of evolution, a constant necessity innovation and the eternal escape from competitors. Red Queen's Race is constructed into a miniature civilization, or rather one growing superorganism, which constantly oscillates between the digital and the physical world. The main consciousness of this association is black majestically looking server that supplies with his computing power and energy all attached printers. They are designed specifically for this purpose, such as abstraction of robotics industry, with an emphasis on a functionally aesthetic form, in yellow-orange color of heavy industrial machinery. The most important and largest part of this system, are entities which printers materialize. They are created according to a living creature of this world, generated by computer, based on a unique code, which is the result of calculating the evolutionary recombination, processed by the server, depending on the reactions of outside observers at the objects which are already created. Sense of each entity is attract attention. How much more, the greater is the chance to continue their code in future generations.

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