Tools For Nonlinear Control Systems Analysis And Design For Aeroengines

The objective of this research was to develop tools for modeling analysis, and control design for unsteady flow and combustion phenomena critical to operation of military aeroengines. We have made significant progress in control-oriented modeling model validation and control design for processes affecting operation of aeroengines. The progress in modeling includes control-oriented reduced order models for turbomachinery flow including compressors, diffusers, recirculation zones, and jets in cross flow. Major breakthrough was achieved in the area of nonlinear model validation and parameter identification, with particular focus on models of combustion instability. In particular, method of nonlinear model validation and parameter identification for systems with non-equilibrium attractors and noise drive systems based on comparison of long-term statistics has been transitioned to internal UTRC projects. New results in control of limit-cycling systems with bounded control were obtained. Significant progress was achieved in adaptive control of combustion instability, control of pressure recovery in diffusers, control of recirculation zone, and control of jets in cross flow. In particular, framework for control of mixing based on hierarchy of vorticity evolution models has been introduced. The framework has been used in control of mixing enhancement in jets in cross-flow and led to experimental validation of model-based analysis.

This book aims to develop systematic design methodologies to model-based nonlinear control of aeroengines, focusing on (1) modelling of aeroengine systems—both component-level and identification-based models will be extensively studied and compared; and (2) advanced nonlinear control designs—set-point control, transient control and limit-protection control approaches will all be investigated. The model-based design has been one of the pivotal technologies to advanced control and health management of propulsion systems. It can fulfil advanced designs such as fault-tolerant control, engine modes control and direct thrust control. As a consequence, model-based design has become an important research area in the field of aeroengines due to its theoretical interests and engineering significance. One of the central issues in model-based controls is the tackling of nonlinearities. There are publications concerning with either nonlinear modelling or nonlinear controls; yet, they are scattered throughout the literature. It is time to provide a comprehensive summary of model-based nonlinear controls. Consequently, a series of important results are obtained and a systematic design methodology is developed which provides consistently enhanced performance over a large flight/operational envelope, and it is thus expected to provide useful guidance to practical engineering in aeroengine industry and research.

"Formal methods is a field of computer science that emphasizes the use of rigorous mathematical techniques for verification and design of hardware and software systems. Analysis and design of nonlinear control design plays an important role across many disciplines of engineering and applied sciences, ranging from the control of an aircraft engine to the design of genetic circuits in synthetic biology. While linear control is a well-established subject, analysis and design of nonlinear control systems remains a challenging topic due to some of the fundamental difficulties caused by nonlinearity. Formal Methods for Control of Nonlinear Systems provides a unified computational approach to analysis and design of nonlinear systems. Features Constructive approach to nonlinear control Rigorous specifications and validated computation Suitable for graduate students and researchers who are interested in learning how formal methods and validated computation can be combined together to tackle nonlinear control problems with complex specifications from an algorithmic perspective. Combines mathematical rigor with practical applications"--

"Formal methods is a field of computer science that emphasizes the use of rigorous mathematical techniques for verification and design of hardware and software systems. Analysis and design of nonlinear control design plays an important role across many disciplines of engineering and applied sciences, ranging from the control of an aircraft engine to the design of genetic circuits in synthetic biology. While linear control is a well-established subject, analysis and design of nonlinear control systems remains a challenging topic due to some of the fundamental difficulties caused by nonlinearity. Formal Methods for Control of Nonlinear Systems provides a unified computational approach to analysis and design of nonlinear systems. Features Constructive approach to nonlinear control Rigorous specifications and validated computation Suitable for graduate students and researchers who are interested in learning how formal methods and validated computation can be combined together to tackle nonlinear control problems with complex specifications from an algorithmic perspective. Combines mathematical rigor with practical applications"--

A systematic computer-aided approach provides a versatile setting for the control engineer to overcome the complications of controller design for highly nonlinear systems. Computer-aided Nonlinear Control System Design provides such an approach based on the use of describing functions. The text deals with a large class of nonlinear systems without restrictions on the system order, the number of inputs and/or outputs or the number, type or arrangement of nonlinear terms. The strongly software-oriented methods detailed facilitate fulfillment of tight performance requirements and help the designer to think in purely nonlinear terms, avoiding the expedient of linearization which can impose substantial and unrealistic model limitations and drive up the cost of the final product. Design procedures are presented in a step-by-step algorithmic format each step being a functional unit with outputs that drive the other steps. This procedure may be easily implemented on a digital computer with example problems from mechatronic and aerospace design being used to demonstrate the techniques discussed. The author’s commercial MATLAB®-based environment, available separately from insert URL here, can be used to create simulations showing the results of using the computer-aided control system design ideas characterized in the text. Academic researchers and graduate students studying nonlinear control systems and control engineers dealing with nonlinear plant, particularly mechatronic or aerospace systems will find Computer-aided Nonlinear Control System Design to be of great practical assistance adding to their toolbox of techniques for dealing with system nonlinearities. A basic knowledge of calculus, nonlinear analysis and software engineering will enable the reader to get the best from this book.

This five year project has brought together researchers in nonlinear control theory (University of California and Caltech) and aeroengine dynamics and control (MIT) to develop new techniques for robust nonlinear Control of aeroengines. Technology transfer to the commercial sector has been achieved through strong and synergistic coupling with Pratt & : Whitney (P & :W) via United Technologies Research Center (UTRC). The specific application areas addressed were active control of. first, compression system rotating stall and surge, and second, blade flutter and forced vibration. These complex physical phenomena, which bear heavily on engine safety and performance, are arguably the most critical considerations in modern aeroengine design. The outcomes of this project are new tools and methods promising to improve both operability and reliability, of military and commercial aeroengines through robust nonlinear control. A highly integrated multi-disciplinary effort has successfully interlaced ideas and results from fluid dynamics, structural dynamics, experiments, and nonlinear control theory. For the highly nonlinear behavior associated with rotating stall and large disturbances new analytical, numerical, and experimental nonlinear techniques have been developed, transitioned to the industrial partner and widely disseminated to the engineering community. The results have appeared in over 40 journal papers, 50 conference proceedings as well as in 2 patents 1.2. Among the important spin-offs of this project are the new AFOSR flow control and mixing projects by M. Krsitc, I. Mezic, and B. Bamieh. They are now better prepared to broaden the scope of control theory as a vital enabling technology.

The major objective of this project is to develop a computer-aided approach to nonlinear stability analysis and nonlinear control system design. This goal is to be obtained by refining the describing function method as a synthesis tool for nonlinear control design. The interim report outlines the approach by this study to meet these goals including an introduction to the INteractive Controls Analysis (INCA) program which was instrumental in meeting these study objectives. A single-input describing function (SIDF) design methodology was developed in this study; coupled with the software constructed in this study, the results of this project provide a comprehensive tool for design and integration of nonlinear control systems. Wie, Bong and Anthony, Tobin Unspecified Center COMPUTER TECHNIQUES; CONTROL SYSTEMS DESIGN; INTERACTIVE CONTROL; NONLINEAR SYSTEMS; COMPUTER PROGRAMS; DESCRIPTIONS; INPUT; METHODOLOGY...