Η παρούσα διπλωματική εργασία πραγματεύεται τη μελέτη μιας διάταξης ανεμογεννήτριας με σύγχρονη μηχανή με μόνιμους μαγνήτες η οποία συνδέεται μέσω dc διασύνδεσης με το δίκτυο. Τη dc διασύνδεση τη δημιουργεί ένας dc πυκνωτής και από την πλευρά της μηχανής υπάρχει ένας ac/dc πλήρως ελεγχόμενος ανορθωτής ισχύος ενώ από την πλευρά του δικτύου βρίσκεται ένας dc/ac πλήρως ελεγχόμενος αντιστροφέας ισχύος. Σκοπός της εργασίας είναι αρχικά να μελετήσουμε θεωρητικά το συνολικό σύστημα της ανεμογεννήτριας χρησιμοποιώντας το μετασχηματισμό Park για τη μοντελοποίηση του στο d-q πλαίσιο αναφοράς. Στη συνέχεια προχωρούμε στον υπολογισμό των εξισώσεων στο χώρο κατάστασης και τελικά προτείνουμε ένα σύστημα ελέγχου το οποίο βασίζεται στους PI ελεγκτές. Τέλος, προσομοιώνουμε το παραπάνω σύστημα με τη βοήθεια της εφαρμογής Simulink του λογισμικού MATLAB και μελετώντας τα αποτελέσματα, εξάγουμε τα ανάλογα συμπεράσματα. / This thesis deals with the study of a wind turbine device with a permanent magnet synchronous machine which is connected with the grid side via a dc interconnection. The dc link is created by a dc capacitor and on the machine side there is an ac / dc power converter while on the grid side there is a dc / ac power converter, both of which are totally controlled. Aim of this thesis is to study the complete wind turbine system in the d-q rotating vertical axes system through the Park transformation. Then we calculate the state space equations and propose a control system based on PI controllers. Finally, we simulate the complete system with the MATLAB Simulink and having studied the results, we draw conclusions.

The motion of ocean waves can be captured and converted into usable electricity. This indicates that wave power has the potential to supply electricity to grids like wind or solar power. A point absorbing wave energy converter (WEC) system has been developed for power production at Uppsala University. This system contains a semi-submerged buoy on the water surface driving a linear synchronous generator placed on the seabed. The concept is to connect many small units together, to form a wave farm for large-scale electricity generation. A lot of effort has gone into researching how to enhance the power absorption from each WEC unit. These improvements are normally done separately for the buoy, the generator or the electrical system, due to the fact that modelling the dynamic behavior of the entire WEC system is complicated and time consuming. Therefore, a quick, yet simple, assessment tool is needed.  This thesis focuses on studying the use of the equivalent circuit as a WEC system modelling tool. Based on the force analysis, the physical elements in an actual WEC system can be converted into electrical components. The interactions between the regular waves, the buoy, and the Power Take-off mechanism can be simulated together in one circuit network. WEC performance indicators like the velocity, the force, and the power can be simulated directly from the circuit model. Furthermore, the annual absorbed electric energy can be estimated if the wave data statistics are known. The linear and non-linear equivalent circuit models developed in this thesis have been validated with full scale offshore experimental results. Comparisons indicate that the simplest linear circuit can predict the absorbed power reasonably well, while it is not so accurate in estimating the peak force in the connection line. The non-linear circuit model generates better estimations in both cases. To encourage researchers from different backgrounds to adapt and apply the circuit model, an instruction on how to establish a non-linear equivalent circuit model is supplied, as well as on how to apply the model to accelerate the decision making process when planning a WEC system.

Spacecraft simulator platforms can simulate the microgravity environment of space on Earth, for the purposes of testing the Attitude and Orbit Control Subsystem of satellites. In order to do this, the satellite is mounted on a bench and the combined center of mass of this assembly is controlled by a series of moving masses. The objective is to bring this center or mass as close as possible to the center of rotation, since solids in microgravity always rotate around their own center of mass. The air-bearing platform located, designed and built at the NanoSat Laboratory of the Kiruna Space Campus of the Luleå University of Technology makes use of four balancing masses, which are displaced by that number of linear actuators. This document explains the process followed to design an algorithm for the estimation of the center of mass and the subsequent calculation of the required positions of the balancing masses to bring this center of mass back to the center of rotation. First, the equations of rotational motion of the bench were found through two formulations: quaternions and Euler-Lagrange. Secondly, these equations were used to obtain an estimation of the center of mass via Batch Least-Squares. Thirdly, the equations of the center of mass of a system of point masses were used to find the proper positions of the balancing masses. Finally, the complete algorithm was tested with Hardware-in-the-Loop simulations before testing it in the real hardware of the platform. The developed algorithm was not capable of estimating the center of mass with sufficient accuracy, which invalidated the obtained actuator positions, and thus was not able to compensate the offset of the center of mass. Recommended lines of development are provided to assist on the continuation of this work.

In this report, the modeling process and operation of an autonomous hybrid power system is studied. It is built based on a hypothetical case study of electrification of a remote village of 100 inhabitants in Kenya. The power demand is estimated and the costs of equipment components are specified after extensive research, so that the techno-economical design of the system can be carried out. The microgrid consists of photovoltaics, wind turbine, batteries, diesel genset, basic loads and water pumping and purification load. The system is modeled and simulated in terms of power management and its operation as well as the performance of the dispatch strategy is assessed. Problems like the management of extra power or tackling the deficit of power in the system are addressed. The model represents reliably the behavior of the microgrid and several improving actions are suggested.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O presente trabalho objetiva o desenvolvimento de uma estratégia de controle adaptativa capaz de estabilizar e atuar no cumprimento de trajetórias de um veículo quadricóptero. O quadricóptero é definido como uma aeronave de pousos de decolagens verticais (VTOL) e emergiu a partir da segunda metade da década de 2000 como uma plataforma promissora para utilização em diversas finalidades devido, principalmente, à sua simplicidade mecânica, alto payload e robustez. Por isso, essa aeronave tem sido vastamente explorada desde então nas publicações da área, preocupando-se, como este trabalho, em propor metodologias numéricas para aprimorar a autonomia e confiabilidade na utilização prática destes veículos. O modelo matemático do helicóptero foi obtido a partir do formalismo de Euler- Lagrange, considerando um corpo rígido, simétrico e tomando a origem do sistema de coordenadas coincidente com o centro de gravidade do veículo. Como forma de se obter um modelo mais fiel à situação real de voo, o Efeito Giroscópio sobre corpo e as hélices foi considerado. Sob a ótica da engenharia de controle, é considerado um sistema subatuado por possuir 4 entradas (associadas às quatro velocidades angulares dos rotores) e seis variáveis de estado (correspondentes às coordenadas generalizadas da mecânica lagrangeana). A partir do modelo obtido, um simulador foi desenvolvido na plataforma Simulink® como método para aferir sobre a eficácia das estratégias de controle propostas. Inicialmente, foi efetivada a estabilização do veículo por um controlador PID clássico e, em seguida, os resultados foram comparados com os dados presentes na literatura a fim de garantir o bom funcionamento da rotina desenvolvida. Finalmente, uma estratégia de controle PID adaptativo foi proposta a partir da implementação de programação heurística baseada em Algoritmos Genéticos para identificar os ganhos ideais dos controladores das coordenadas z, x e y. Os resultados apontaram um considerável ganho de desempenho do método adaptativo sobre o PID clássico para estabilização e seguimento de trajetórias de um veículo quadrirrotor na presença de variação de massa. / This work aims the development of an adaptive control strategy on stabilization and path tracking tasks of a quadrotor vehicle. The quadrotor is defined as a Vertical Take Off and Landing (VTOL) aircraft and it has emerged, in the second half of the 2000s as a promising platform for use in many purposes, mainly due to its mechanical simplicity, high payload and robustness. Therefore, this aircraft has been widely exploited on this area, which researches has focusing, as this work , to propose numerical methods in order to improve the autonomy and reliability in practical use of these vehicles. The helicopter model of the helicopter was obtained from the Euler-Lagrange formalism, considering it as a rigid body, symmetrical and taking the origin of the coordinate system coincides with the center of gravity of the vehicle. In order to obtain a more accurate model compared to the actual flight situation, the Gyro effect on body and propellers was considered. From the perspective of control engineering, it is considered an underactuated system which has 4 inputs (associated with four angular velocities of the rotors) and six state variables (corresponding to generalized coordinates of Lagrangian mechanics) A simulator was developed on Simulink® platform evaluated from the model obtained as a way to check on the effectiveness of the proposed control strategies. Initially, it was implemented a classic PID controller in order to stabilize the, and then the results were compared to the data present in the literature in order to ensure the reliability of the routine implemented. Lastly, an adaptive PID control strategy was proposed from the implementation of heuristic programming based on genetic algorithms to identify optimal gains controllers to the coordinates z , x and y subsystems. The results indicated a significant performance gain of the adaptive method over the classic PID for stabilization and path tracking tasks of a quadrirrotor vehicle in the presence of mass variation. / Dissertação (Mestrado)

abstract: This thesis introduces the Model-Based Development of Multi-iRobot Toolbox (MBDMIRT), a Simulink-based toolbox designed to provide the means to acquire and practice the Model-Based Development (MBD) skills necessary to design real-time embedded system. The toolbox was developed in the Cyber-Physical System Laboratory at Arizona State University. The MBDMIRT toolbox runs under MATLAB/Simulink to simulate the movements of multiple iRobots and to control, after verification by simulation, multiple physical iRobots accordingly. It adopts the Simulink/Stateflow, which exemplifies an approach to MBD, to program the behaviors of the iRobots. The MBDMIRT toolbox reuses and augments the open-source MATLAB-Based Simulator for the iRobot Create from Cornell University to run the simulation. Regarding the mechanism of iRobot control, the MBDMIRT toolbox applies the MATLAB Toolbox for the iRobot Create (MTIC) from United States Naval Academy to command the physical iRobots. The MBDMIRT toolbox supports a timer in both the simulation and the control, which is based on the local clock of the PC running the toolbox. In addition to the build-in sensors of an iRobot, the toolbox can simulate four user-added sensors, which are overhead localization system (OLS), sonar sensors, a camera, and Light Detection And Ranging (LIDAR). While controlling a physical iRobot, the toolbox supports the StarGazer OLS manufactured by HAGISONIC, Inc. / Dissertation/Thesis / Model-Based Development of Multi-iRobot Toolbox (version 1.0) / M.S. Computer Science 2012

abstract: As the complexity of robotic systems and applications grows rapidly, development of high-performance, easy to use, and fully integrated development environments for those systems is inevitable. Model-Based Design (MBD) of dynamic systems using engineering software such as Simulink® from MathWorks®, SciCos from Metalau team and SystemModeler® from Wolfram® is quite popular nowadays. They provide tools for modeling, simulation, verification and in some cases automatic code generation for desktop applications, embedded systems and robots. For real-world implementation of models on the actual hardware, those models should be converted into compilable machine code either manually or automatically. Due to the complexity of robotic systems, manual code translation from model to code is not a feasible optimal solution so we need to move towards automated code generation for such systems. MathWorks® offers code generation facilities called Coder® products for this purpose. However in order to fully exploit the power of model-based design and code generation tools for robotic applications, we need to enhance those software systems by adding and modifying toolboxes, files and other artifacts as well as developing guidelines and procedures. In this thesis, an effort has been made to propose a guideline as well as a Simulink® library, StateFlow® interface API and a C/C++ interface API to complete this toolchain for NAO humanoid robots. Thus the model of the hierarchical control architecture can be easily and properly converted to code and built for implementation. / Dissertation/Thesis / M.S. Computer Science 2013

In this thesis, the concept of virtual reality has been elaborated in the context of games, industrial design and manufacturing. The main purpose of this master’s thesis is to create a virtual environment for games that are near to the reality and according to the human nature through aspects like better interface, simulation, lights, shadow effects and their types. The importance of these aspects regarding realistic virtual environment is complemented through the comparison between two environments i.e. desktop and CAVE on a flight simulation program.

Currently, there is lack of effective and scalable methods to specify and ana-lyze requirements specifications, and verify the behavioral models of embed-ded systems. Most embedded systems requirements are expressed in naturallanguage which is flexible and intuitive but frequently ambiguous, vague andincomprehensive. Besides to natural language, template-based requirementsspecification methods are used to specify requirements specifications (esp. insafety-critical applications), which reduce ambiguity and improves the com-prehensibility of the specifications. However, the template-based method areusually rigid due to the fixed structures of the templates. They also lack meta-models for extensibility, and template selection is challenging.In this thesis, we proposed a domain specific language for embedded sys-tems, called ReSA, which is constrained natural language but flexible enoughto allow engineers to use different constructs to specify requirements. Thelanguage has formal semantics in proportional logic and description logic thatenables non-trivial and rigorous analysis of requirements specification, e.g.,consistency checking, completeness of specifications, etc.Moreover, we propose a scalable formal verification of Simulink models,whichisusedtodescribethebehaviorofsystemsthroughcommunicatingfunc-tional blocks. In industry, Simulink is the de facto modeling and analysis en-vironment of embedded systems. It is also used to generate code automati-cally from special Simulink models for various hardware platforms. However,Simulink lacks formal approach to verify large and hybrid Simulink models.Therefore, we also propose a formal verification of Simulink models, repre-sented as stochastic timed automata, using statistical model checking, whichhas proven to scale for industrial applications.We validate our approaches on industrial use cases from the automotiveindustry. These includes Adjustable Speed Limiter (ASL) and Brake-By-Wire(BBW) systems from Volvo Group Trucks Technology, both safety-critical. / Verispec

The field of robotics is becoming increasingly more important and consequently, students need better tools to gain knowledge and experience with them. The University of Skövde was interested in developing a learning tool focused on a virtual simulation of mobile robots. Despite the fact that there are several programmes to create this tool, MATLAB was preferable because of its strong presence in educational institutions. The objectives were oriented towards testing different robot kinematics in an adjustable virtual 3D environment. Moreover, the simulation needed a part in which future users could design own algorithms in order to control the AGVs. Therefore, sensors such as LIDAR sensors were necessary to enable a possible interaction between the robot and the scenario created. This project was developed with a previous study and a comparison of some MATLAB projects and tools. After that, the scenario and the simulation were produced. As a result, a virtual simulation has been created emphasising that the user could modify and adapt multiple parameters such as the size of the AGV, the form of the virtual environment or the selection of forward or inverse kinematics in order to develop different types of algorithms. Other features can be adjusted manually such as the type or number of sensors as well as SLAM conditions. Finally, this thesis was conducted to give a basis about mobile robots and to be a first step for operating with real robots. The simulation also provides an easy to use interface in which students can keep working in it through the introduction of new applications related to image processing or more sophisticated algorithms and controllers.