No description available.

No description available.

No description available.

No description available.

The servosystems which drive a milling table must be capable of asymptotic tracking and disturbance rejection, and must be robust. The internal model principle is a general method developed by Davison, Desoer and Wonham which achieves asymptotic tracking and disturbance rejection, and is robust. In this thesis, a state-variable control system for the positioning of a milling table is designed by using the internal model principle. The control system is simulated as both a continuous-time system and as a discrete-time system. Results of the simulation indicate that a microprocessor-driven version of the state-variable discrete-time control system is a feasible and practical method of control. / M.S.

A method utilizing H2 control concepts and the numerical method of Polynomial Chaos was developed in order to create a novel robust probabilistically optimal control approach. This method was created for the practical reason that uncertainty in parameters tends to be inherent in system models. As such, the development of new methods utilizing probability density functions (PDFs) was desired. From a more theoretical viewpoint, the utilization of Polynomial Chaos for studying and designing control systems has not been very thoroughly investigated. The current work looks at expanding the H2 and related Linear Quadratic Regulator (LQR) control problems for systems with parametric uncertainty. This allows solving deterministic linear equations that represent probabilistic linear differential equations. The application of common LTI (Linear Time Invariant) tools to these expanded systems are theoretically justified and investigated. Examples demonstrating the utilized optimization process for minimizing the H2 norm and parallels to LQR design are presented. The dissertation begins with a thorough background section that reviews necessary probability theory. Also, the connection between Polynomial Chaos and dynamic systems is explained. Next, an overview of related control methods, as well as an in-depth review of current Polynomial Chaos literature is given. Following, formal analysis, related to the use of Polynomial Chaos, is provided. This lays the ground for the general method of control design using Polynomial Chaos and H2. Then an experimental section is included that demonstrates controller synthesis for a constructed probabilistic system. The experimental results lend support to the method. / Ph. D.

The study of robotics cannot be satisfactorily pursued without access to working robots. The inexpensive Rhino robot arm is one that academic institutions can easily obtain for educational purposes. This thesis presents a new controller that replaces the original Rhino controller, which in many ways was not suited, or was too limited, for experimentation. A comparison of the old and new controllers is given, but the primary purpose of this thesis is to provide complete details of the new controller, and its use. The conclusion discusses the performance of the new controller and areas of experimentation to which it might be applied. / Master of Science

Controladores PID são amplamente utilizados no controle de processos industriais. Estes controladores precisam necessariamente ser ajustados adequadamente a fim de garantir a correta operação do processo controlado. A fim de suprir esta necessidade surgiram os chamados métodos de ajuste para controladores PID, inicialmente propostos por John Ziegler e Nathaniel B. Nichols em 1942. Desde então muitos outros métodos de ajuste baseados nas idéias de Ziegler e Nichols foram propostos, surgindo assim uma família de métodos afins. Em vista da simplicidade de implementação e do consequente baixo custo computacional envolvido, estes métodos mostraram-se adequados para serem incorporados ao firmware de controladores PID industriais de baixo custo. Estes métodos acabaram por gerar um legado tal que sua utilização persiste intensamente até os dias de hoje. No entanto, frente à crescente oferta de microcontroladores de baixo custo e alto desempenho, o custo computacional de um método de ajuste vem perdendo relevância. Isso abre margem para explorar outros métodos que proporcionem melhor desempenho e robustez, mas, por ventura, demandem mais recursos computacionais. Dessa forma, este trabalho propõe-se a avaliar métodos alternativos que sejam compatíveis com os recursos computacionais atuais. Métodos com maior custo computacional, como o Virtual Reference Feedback Tuning (VRFT), Iterative Feedback Tuning (IFT) e Iterative Correlation-based Tuning (ICbT), são apresentados como candidatos para serem incorporados ao firmware de controladores PID industriais. Tratam-se de métodos diretos de ajuste baseado em dados onde os parâmetros do controlador são determinados de forma que o comportamento do sistema em malha fechada seja tal que minimize um critério de desempenho definido a priori. Através deste critério de desempenho pode-se definir o comportamento desejado para o sistema em malha fechada. Neste trabalho são analisadas as principais características destes métodos, resultados obtidos e custo computacional. Com base nos resultados desta análise é mostrado que os métodos VRFT, IFT e ICbT podem ser utilizados como alternativa para o ajuste (incorporado ao firmware) de controladores PID industriais. / PID controllers are widely used in industrial process control. These controllers must necessarily be properly tuned to ensure the correct operation of the controlled process. In order to meet this need, the so-called tuning methods for PID controllers have emerged, initially proposed by John Ziegler and Nathaniel B. Nichols in 1942. Since then many other controller design methods based on the ideas of Ziegler and Nichols have been proposed, giving rise to a family of related methods. Given the simplicity of implementation and the low computational effort involved, these methods are suitable to be incorporated into the firmware of low cost industrial PID controllers. These methods have generated such a legacy that its use remains intense until the present day. However, with the growing offer of low cost and high performance microcontrollers, the computational effort of a tuning method is becoming less important. This opens up scope for exploring other methods that provide better performance and robustness, possibly at the cost of demanding more computational resources. This study aims to evaluate alternative methods that are compatible with current computational resources. Methods with higher computational effort, such as Virtual Reference Feedback Tuning (VRFT), Iterative Feedback Tuning (IFT) and Iterative Correlation based Tuning (ICbT) are presented as candidates to be incorporated into the firmware of industrial PID controllers. These are direct data-based methods for the adjustment of controllers where the parameters are determined such that the behavior of the closed-loop system is such as to minimize a performance criterion defined a priori. Through this performance criterion one can specify the desired behavior for the closed-loop system. This work analyzes the main characteristics of these methods, results and computational effort. Based on the results of this analysis it is shown that the methods VRFT, IFT and ICbT can be used as an alternative to the adjustment (build into the firmware) of industrial PID controllers.

Design control is a relevant concept for any age and any context of urban development by use of many varying tools from highly prescriptive ones to flexible guidance in order to control design of urban space and places. Production of clear definitions and types for the tools is critical for effective use of the design tools to guide and code the urban design. Distinctive parameters for the definitions and types of the design control tools are scale of intervention, level of prescription and contents and component of the tool. In this thesis, design control tools including design guides, briefs, frameworks and design codes are analysed in terms of this parameters, in order to reach the aim of the thesis which is building taxonomy of design control tools and taxonomy of their contents and components by analysing contemporary design control tools.

Offshore wind power production is an attractive clean energy option, but the difficulty of access can lead to expensive and rare opportunities for maintenance. Smart loads management (controls) are investigated for their potential to increase the fatigue life of damaged offshore wind turbine rotor blades. This study will consider two commonly encountered damage types for wind turbine blades, the trailing edge disbond (bond line failure) and shear web disbond, and show how 3D finite element modeling can be used to quantify the effect of operations and control strategies designed to extend the fatigue life of damaged blades. Modern wind turbine blades are advanced composite structures, and blade optimization problems can be complex with many structural design variables and a wide variety of aeroelastic design requirements. The multi-level design method is an aeroelastic structural design technique for beam-like structures in which the general design problem is divided into a 1D beam optimization and a 2D section optimization. As a demonstration of aeroelastic design, the multi-level design method is demonstrated for the internal structural design of a modern composite rotor blade. Aeroelastic design involves optimization of system geometry features as well as internal features, and this is demonstrated in the design of a flying wing aircraft. Control methods such as feedback control also have the capability alleviate aeroelastic design requirements and this is also demonstrated in the flying wing aircraft example. In the case of damaged wind turbine blades, load mitigation control strategies have the potential to mitigate the effects of damage, and allow partial operation to avoid shutdown. The load mitigation strategies will be demonstrated for a representative state-of-the-art wind turbine (126m rotor diameter). An economic incentive will be provided for the proposed operations strategies, in terms of weighing the cost and risk of implementation against the benefits of increased revenue due to operation of damaged turbines. The industry trend in wind turbine design is moving towards very large blades, causing the basic design criterion to change as aeroelastic effects become more important. An ongoing 100 m blade (205 m rotor diameter) design effort intends to investigate these design challenges. As a part of that effort, this thesis will investigate damage tolerant design strategies to ensure next-generation blades are more reliable.