Este trabalho apresenta maneiras de trabalhar com o controle de potência reativa e estabilidade de tensão em microgrids. A estratégia de controle utilizada é o Controle por Tensão Distribuída (Distributed Voltage Control - DVC), ou controle por tensões distribuídas, um laço integral que considera as potências reativas em todas as barras como entradas e as tensões respectivas como sinais de controle. Diferentes estratégias de controle para distribuição de potência foram propostas e analisadas, sempre enfatizando seus aspectos conceituais. O cálculo dos ganhos do controlador, embora fundamental para o sucesso de qualquer estratégia de controle, geralmente não é discutido, e não são dados métodos ou linhas gerais para esta tarefa. Neste trabalho, apresentamos e discutimos diferentes metodologias para o projeto de ganhos de controle em DVC. Além disso, sendo o sistema não-linear, grandes variações de performance podem ser observadas se os mesmos ganhos de controle são usados para todos os pontos de operação, o que motiva a proposta de uma estratégia de programação de ganhos, também apresentada neste trabalho. / This text deals with the control of reactive power distribution and voltage stability in microgrids. The control strategy studied is the Distributed Voltage Control (DVC), an integral loop considering entries as reactive in every bus and the bus voltages as control signals. Different control strategies for power distribution have been proposed and analysed, always emphasising its conceptual aspects; design of the controller’s gains, however fundamental for the success of any control strategy, is usually not discussed, and no methods or guideline are given for this task. In this text we present and discuss different methodologies for tuning the control gains in DVC. Moreover, since power systems are nonlinear, large variations in performance can be observed if the same control gains are used for all operating points, which motivates the proposal of a gain scheduling strategy, also presented in here.

Este trabalho apresenta maneiras de trabalhar com o controle de potência reativa e estabilidade de tensão em microgrids. A estratégia de controle utilizada é o Controle por Tensão Distribuída (Distributed Voltage Control - DVC), ou controle por tensões distribuídas, um laço integral que considera as potências reativas em todas as barras como entradas e as tensões respectivas como sinais de controle. Diferentes estratégias de controle para distribuição de potência foram propostas e analisadas, sempre enfatizando seus aspectos conceituais. O cálculo dos ganhos do controlador, embora fundamental para o sucesso de qualquer estratégia de controle, geralmente não é discutido, e não são dados métodos ou linhas gerais para esta tarefa. Neste trabalho, apresentamos e discutimos diferentes metodologias para o projeto de ganhos de controle em DVC. Além disso, sendo o sistema não-linear, grandes variações de performance podem ser observadas se os mesmos ganhos de controle são usados para todos os pontos de operação, o que motiva a proposta de uma estratégia de programação de ganhos, também apresentada neste trabalho. / This text deals with the control of reactive power distribution and voltage stability in microgrids. The control strategy studied is the Distributed Voltage Control (DVC), an integral loop considering entries as reactive in every bus and the bus voltages as control signals. Different control strategies for power distribution have been proposed and analysed, always emphasising its conceptual aspects; design of the controller’s gains, however fundamental for the success of any control strategy, is usually not discussed, and no methods or guideline are given for this task. In this text we present and discuss different methodologies for tuning the control gains in DVC. Moreover, since power systems are nonlinear, large variations in performance can be observed if the same control gains are used for all operating points, which motivates the proposal of a gain scheduling strategy, also presented in here.

Este trabalho apresenta maneiras de trabalhar com o controle de potência reativa e estabilidade de tensão em microgrids. A estratégia de controle utilizada é o Controle por Tensão Distribuída (Distributed Voltage Control - DVC), ou controle por tensões distribuídas, um laço integral que considera as potências reativas em todas as barras como entradas e as tensões respectivas como sinais de controle. Diferentes estratégias de controle para distribuição de potência foram propostas e analisadas, sempre enfatizando seus aspectos conceituais. O cálculo dos ganhos do controlador, embora fundamental para o sucesso de qualquer estratégia de controle, geralmente não é discutido, e não são dados métodos ou linhas gerais para esta tarefa. Neste trabalho, apresentamos e discutimos diferentes metodologias para o projeto de ganhos de controle em DVC. Além disso, sendo o sistema não-linear, grandes variações de performance podem ser observadas se os mesmos ganhos de controle são usados para todos os pontos de operação, o que motiva a proposta de uma estratégia de programação de ganhos, também apresentada neste trabalho. / This text deals with the control of reactive power distribution and voltage stability in microgrids. The control strategy studied is the Distributed Voltage Control (DVC), an integral loop considering entries as reactive in every bus and the bus voltages as control signals. Different control strategies for power distribution have been proposed and analysed, always emphasising its conceptual aspects; design of the controller’s gains, however fundamental for the success of any control strategy, is usually not discussed, and no methods or guideline are given for this task. In this text we present and discuss different methodologies for tuning the control gains in DVC. Moreover, since power systems are nonlinear, large variations in performance can be observed if the same control gains are used for all operating points, which motivates the proposal of a gain scheduling strategy, also presented in here.

O objetivo do trabalho é apresentar dois algoritmos para a solução de problemas de controle ótimo quadrático robusto com restrições, dentro de um contexto de controladores preditivos (MPC do inglês Model Predictive Control). Inicialmente apresentamos uma breve introdução aos algoritmos MPC, com ênfase na abordagem do controlador linear quadrático. Em seguida são apresentados os dois algoritmos de interesse, que utilizam técnicas de otimização LMI. Dessa forma as restrições e as incertezas podem ser colocadas em formas computacionalmente tratáveis. Por fim são realizadas simulações e comparações entre esses algoritmos, bem como com técnicas de MPC encontradas na literatura atual. / The goal of the work is to present two algorithms for the solution of robust quadratic optimal control problems with restrictions, within a model predictive control (MPC) setup. Initially we present a brief introduction of the MPC algorithms, emphasizing the linear quadratic controller approach. Next the two algorithms of interest, using LMI optimization techniques, are presented. By using this technique the restrictions and uncertainties can be written in a computational way. Finally some simulations and comparisons between these algorithms, as well as with MPC techniques found in the current literature, are performed.

This thesis investigates and implements the sensor fusion necessary to autonomously reverse a full size truck and trailer system. This is done using a LiDAR mounted on the rear of the truck along with a RTK-GPS. It is shown that the relative angles between truck-dolly and dolly-trailer can be estimated, along with global position and global heading of the trailer. This is then implemented in one of Scania's test vehicles, giving it the ability to continuously estimate these states. A controller is then implemented, showing that the full scale system can be stabilised in reverse motion. The controller is tested both on a static reference path and a reference path received from a motion planner. In these tests, the controller is able to stabilise the system well, allowing the truck to do complex manoeuvres backwards. A small lateral tracking error is present, which needs to be further investigated.

Direct lift control for aircraft has been around in the aeronautical industry for decades but is mainly used in commercial aircraft with dedicated direct lift control surfaces. The focus of this thesis is to investigate if direct lift control is feasible for a fighter aircraft, similar to Saab JAS 39 Gripen, without dedicated control surfaces. The modelled system is an aircraft that is inherently unstable and contains nonlinearities both in its aerodynamics and in the form of limited control surface deflection and deflection rates. The dynamics of the aircraft are linearised around a flight case representative of a landing scenario. Direct lift control is then applied to give a more immediate relation from pilot stick input to change in flight path angle while also preserving the pitch attitude. Two different control strategies, linear quadratic control and model predictive control, were chosen for the implementation. Since fighter aircraft are systems with fast dynamics it was important to limit the computational time. This constraint motivated the use of specialised methods to speed up the optimisation of the model predictive controller. Results from simulations in a nonlinear simulation environment supplied by Saab, as well as tests in high-fidelity flight simulation rigs with a pilot, proved that direct lift control is feasible for the investigated fighter aircraft. Sufficient control authority and performance when controlling the flight path angle were observed. Both developed controllers have their own advantages and which strategy is the most suitable depends on what the user prioritises. Pilot workload during landing as well as precision at touch down were deemed similar to conventional control.

<p>Networked embedded control systems are present almost everywhere. A recent trend is to introduce wireless sensor networks in these systems, to take advantage of the added mobility and flexibility offered by wireless solutions. In such networks, the sensor observations are typically quantized and transmitted over noisy links. Concerning the problem of closed-loop control over such non-ideal communication channels, relatively few works have appeared so far. This thesis contributes to this field, by studying some fundamentally important problems in the design of joint source--channel coding and optimal control.</p><p>The main part of the thesis is devoted to joint design of the coding and control for scalar linear plants, whose state feedbacks are transmitted over binary symmetric channels. The performance is measured by a finite-horizon linear quadratic cost function. The certainty equivalence property of the studied systems is utilized, since it simplifies the overall design by separating the estimation and the control problems. An iterative optimization algorithm for training the encoder--decoder pairs, taking channel errors into account in the quantizer design, is proposed. Monte Carlo simulations demonstrate promising improvements in performance compared to traditional approaches.</p><p>Event-triggered control strategies are a promising solution to the problem of efficient utilization of communication resources. The basic idea is to let each control loop communicate only when necessary. Event-triggered and quantized control are combined for plants affected by rarely occurring disturbances. Numerical experiments show that it is possible to achieve good control performance with limited control actuation and sensor communication.</p>

We study canonical forms for Hamiltonian and symplectic matrices or pencils under equivalence transformations which keep the class invariant. In contrast to other canonical forms our forms are as close as possible to a triangular structure in the same class. We give necessary and sufficient conditions for the existence of Hamiltonian and symplectic triangular Jordan, Kronecker and Schur forms. The presented results generalize results of Lin and Ho [17] and simplify the proofs presented there.

We study canonical forms for Hamiltonian and symplectic matrices or pencils under equivalence transformations which keep the class invariant. In contrast to other canonical forms our forms are as close as possible to a triangular structure in the same class. We give necessary and sufficient conditions for the existence of Hamiltonian and symplectic triangular Jordan, Kronecker and Schur forms. The presented results generalize results of Lin and Ho [17] and simplify the proofs presented there.

Networked embedded control systems are present almost everywhere. A recent trend is to introduce wireless sensor networks in these systems, to take advantage of the added mobility and flexibility offered by wireless solutions. In such networks, the sensor observations are typically quantized and transmitted over noisy links. Concerning the problem of closed-loop control over such non-ideal communication channels, relatively few works have appeared so far. This thesis contributes to this field, by studying some fundamentally important problems in the design of joint source--channel coding and optimal control. The main part of the thesis is devoted to joint design of the coding and control for scalar linear plants, whose state feedbacks are transmitted over binary symmetric channels. The performance is measured by a finite-horizon linear quadratic cost function. The certainty equivalence property of the studied systems is utilized, since it simplifies the overall design by separating the estimation and the control problems. An iterative optimization algorithm for training the encoder--decoder pairs, taking channel errors into account in the quantizer design, is proposed. Monte Carlo simulations demonstrate promising improvements in performance compared to traditional approaches. Event-triggered control strategies are a promising solution to the problem of efficient utilization of communication resources. The basic idea is to let each control loop communicate only when necessary. Event-triggered and quantized control are combined for plants affected by rarely occurring disturbances. Numerical experiments show that it is possible to achieve good control performance with limited control actuation and sensor communication. / QC 20101109