Dynamics And Control Of Structures: A Modal Approach (mechanical Engineering Series)

Robots, aerospace structures, active earthquake-damping devices of tall buildings, and active sound suppression are examples of the application of structural dynamics and control methods. This book addresses the structural dynamics and control problems encountered by mechanical, civil, and control engineers. Many problems presented in this book originated in recent applications in the aerospace industry, and have been solved using the approach presented here. Dynamics analysis and controller design for flexible structures require a special approach due to the large size of structural models, and because flexible structure testing and control typically requires massive instrumentation (sensors and actuators). But the rapid development of new technologies and the increased power of computers allows for the formulation and solution of engineering problems that seemed to be unapproachable not so very long ago. The modal approach was chosen in this book. It has a long tradition in structural engineering (see, e.g., [84], [87], and [26]) and is also used in control system analysis, e.g., [93]. Its usefulness, thoroughly tested, does not need extensive justification. Both structural testing and analysis give priority to the modal representation, due to its compactness, simplicity, and explicit physical interpretation. Also, many useful structural properties are properly exposed only in modal coordinates. In this book the modal approach, preferred by structural engineers, is extended into control engineering, giving new analytical results, and narrowing the gap between structural and control analysis. Advanced Structural Dynamics and Active Control of Structures describes comparatively new areas of structural dynamics and control, and presents new tools to solve problems of dynamics and control. It applies control system methods (such as state space representation, controllability and observability, grammians, system norms, and Markov parameters) to solve structural dynamics problems (e.g., sensor and actuator placement, identification, or damage detection), It uses structural methods (such as modal analysis, and modal independence) to solve control problems (e.g., the design of LQG and H¥ controllers), and provides new insight into well-known control laws. It is based on practical applications, originated from developing and applying techniques of structural dynamics, identification, and control to antennas and radiotelescopes. It uses approximate approach in order to simplify analysis of large structural models (for example, to obtain Hankel singular values for a structure with thousands degrees of freedom), and to represent properties of large structures in closed form - a form that is simple and easy to apprehend. This book is a revision and continuation of Gawronski's previous book, Dynamics and Control of Structures. Three new chapters discuss special models, modal actuators and sensors, and system identification. Other chapters have been significantly revised and supplemented with new topics, including discrete-time models of structures, limited-time and frequency grammians and reduction, almost-balanced modal models, simultaneous placement of sensors and actuators, and structural damage detection. The updated and expanded appendices include programs that apply methods presented in the book in Matlab® simulations, Matlab programs that solve examples from each chapter, and additional appendix with data of models presented in the book. Appropriate for graduate courses on vibration and structural dynamics, and in control system courses with application to structural control, Advanced Structural Dynamics and Active Control of Structures will also be useful for engineers who deal with structural dynamics and control. Some praise for Wodek Gawronski's Dynamics and Control of Structures: A Modal Approach: "This book succeeds well in its intent to build a bridge between the structural engineer and the control engineer to control flexible structures. The needed ingredients to this end from both fields are presented side-by-side in an integrated fashion and illustrated by good design examples of increasing challenge. Dynamics and Control of Structures is a very good reference book ..." -Applied Mechanics Reviews "... An excellent, clearly written, up-to-date exposition which should serve graduate students and researchers as a bridge between structural and control engineering." -Zentralblatt für Mathematik Wodek K. Gawronski, Ph.D. is Principal Engineer, Antenna Control Systems for the Jet Propulsion Laboratory at California Institute of Technology, and is an Associate Editor of the Journal of Guidance, Control, and Dynamics (American Institute of Aeronautics and Astronautics) This book addresses problems in structural dynamics and control encountered in such applications as: aerospace structures, robotics, earthquake-damage prevention, and active noise suppression. The rapid developments of new technologies and computer power have made it possible to formulate and solve engineering problems that seemed unapproachable only a few years ago. The treatment combines concepts from control engineering (such as system norms and controllability) and structural engineering (such as modal properties and modal models), thereby both revealing new structural properties as well as giving new insights into well-known laws. The techniques discussed will make it easier for structural engineers to design control systems and for control engineers to deal with structural dynamics. The discussion begins by defining flexible structures and structural models, using such examples as the international space station and the antennas of NASA's deep-space network. The book then turns to controllability and observability; properties of system norms (Häsubinfinityü, Häsub2ü, and Hankel); and model reduction in terms of these norms. A discussion of sensor and actuator location follows: selecting these is rarely an easy task. The concluding chapters discuss the design of dissipative LQG and Häsubinfinityü controllers. Matlab codes for many of the procedures and methods discussed in the book are included "This book is a revision and continuation of Gawronski's previous book, Dynamics and Control of Structures: A Modal Approach. Three new chapters discuss special models, modal actuators and sensors and system identification. Other chapters have been significantly revised and supplemented with new topics, including discrete-time models of structures, limited-time and -frequency grammians and reduction, almost-balanced modal models, simultaneous placement of sensors and actuators, and structural damage detection. The updated and expanded appendices include programs that apply methods presented in the book in Matlab, simulations, Matlab programs that solve examples from each chapter, and an additional appendix with data of models presented in the book." "Appropriate for graduate courses on vibration and structural dynamics, and in control system courses with application to structural control, Advanced Structural Dynamics and Active Control of Structures will also be useful for engineers who deal with structural dynamics and control."--Jacket Front Matter....Pages i-xx Front Matter....Pages 1-1 Introduction....Pages 3-10 Models....Pages 11-31 Controllability and Observability....Pages 32-52 Norms....Pages 53-69 Model Reduction....Pages 70-89 Assignment....Pages 90-99 Actuator and Sensor Placement....Pages 100-128 Front Matter....Pages 129-129 Dissipative Controllers....Pages 131-141 LQG Controllers....Pages 142-176 H ∞ and H 2 Controllers....Pages 177-205 Back Matter....Pages 206-232