154 research outputs found
Dynamic operability assessment : a mathematical programming approach based on Q-parametrization
Bibliography: pages 197-208.The ability of a process plant to guarantee high product quality, in terms of low variability, is emerging as a defining feature when distinguishing between alternative suppliers. The extent to which this can be achieved is termed a plant's dynamic operability and is a function of both the plant design and the control system design. In the limit, however, the closedloop performance is determined by the properties inherent in the plant. This realization of the interrelationship between a plant design and its achievable closed-loop performance has motivated research toward systematic techniques for screening inherently inferior designs. Pioneering research in the early 1980's identified right-half-plane transmission zeros, time delays, input constraints and model uncertainty as factors that limit the achievable closedloop performance of a process. Quantifying the performance-limiting effect of combinations of these factors has proven to be a challenging problem, as reflected in the literature. It is the aim of this thesis to develop a systematic procedure for dynamic operability assessment in the presence of combinations of performance-limiting factors. The approach adopted in this thesis is based on the Q-parametrization of stabilizing linear feedback controllers and involves posing dynamic operability assessment as a mathematical programming problet? In the proposed formulation, a convex objective function, reflecting a measure of closed-loop performance, is optimized over all stable Q, subject. to a set of constraints on the closed-loop behavior, which for many specifications of interest is convex. A discrete-time formulation is chosen so as to allow for the convenient hand.ling of time delays and time-domain constraints. An important feature of the approach is that, due to the convexity, global optimality is guaranteed. Furthermore, the fact that Q parametrizes all stabilizing linear feedback controllers implies that the performance at the optimum represents the best possible performance for any such controller. The results are thus not biased by controller type or tuning, apart from the requirement that the controller be linear
Mixed H2/H∞ control for infinite dimensional systems
The class of infinite dimensional systems often occurs when dealing with distributed
parameter models consisting of partial differential equations. Although forming a
comprehensive description, they mainly become manageable by finite dimensional approximations
which likely neglect important effects, but underlies a certain structure.
In contrast to common techniques for controlling infinite dimensional systems, this
work focuses on using robust control methods. Thus, the uncertainty structure that
occurs due to the discretization shall be taken into account particularly. Additionally,
optimal performance measures can be included into the design process. The mixed
H2/H∞ control approach handles the inclusion of disturbances and inaccuracies while
guaranteeing specified energy or magnitude bounds.
In order to include various of these system requirements, multi-objective robust control
techniques based on the linear matrix inequality framework are utilized. This offers
great flexibility concerning the formulation of the control task and results in convex
optimization problems which can be solved numerically efficient by semi-definite programming.
A flexible robot arm structure serves as the major application example during this
work. The model discretization leads to an LTI system of specified order with an uncertainty
model which is obtained by considering the concrete approximation impact
and frequency domain tests. A structural analysis of the system model relates the
neglected dynamics to a robust characterization. For the objective selection, stability
shall be ensured under all expected circumstances while the aspects of optimal H2 performance,
passive behavior and optimal measurement output selection are included.
The undesirable spillover effect is thoroughly investigated and thus avoided.Tesi
New Approaches in Automation and Robotics
The book New Approaches in Automation and Robotics offers in 22 chapters a collection of recent developments in automation, robotics as well as control theory. It is dedicated to researchers in science and industry, students, and practicing engineers, who wish to update and enhance their knowledge on modern methods and innovative applications. The authors and editor of this book wish to motivate people, especially under-graduate students, to get involved with the interesting field of robotics and mechatronics. We hope that the ideas and concepts presented in this book are useful for your own work and could contribute to problem solving in similar applications as well. It is clear, however, that the wide area of automation and robotics can only be highlighted at several spots but not completely covered by a single book
Robust controller design--minimizing peak-to-peak gain
Includes bibliographical references (p. 87-92).Supported by Wright Patterson Air Force Base. F33615-90-c-3608Munther A. Dahleh
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