Advances in Aeronautical Systems PDF
Preview Advances in Aeronautical Systems
CONTRIBUTORS TO THIS VOLUME J. A. DE ABREU-GARCIA ITZHACK Y. BAR-ITZHACK KENNETH R.BOFF WILLIAM J.CODY DOUGLAS G. DEWOLF PAUL R.FREY T. T HARTLEY GEORGE MEYER WILLIAM B. ROUSE JOSEF SHIN AR P. F SINGER G.ALLAN SMITH D. D. SWORDER HENDRIKUS G. VISSER STEPHEN A. WHITMORE CONTROL AND DYNAMIC SYSTEMS ADVANCES IN THEORY AND APPLICATIONS Edited by C. T. LEONDES School of Engineering and Applied Science University of California, Los Angeles Los Angeles, California and College of Engineering University of Washington Seattle, Washington VOLUME 38: ADVANCES IN AERONAUTICAL SYSTEMS ® ACADEMIC PRESS, INC. Harcourt Brace Jovanovich, Publishers San Diego New York Boston London Sydney Tokyo Toronto This book is printed on acid-free paper. @ Copyright © 1990 by Academic Press, Inc. All Rights Reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publisher. Academic Press, Inc. San Diego, California 92101 United Kingdom Edition published by Academic Press Limited 24-28 Oval Road, London NW1 7DX Library of Congress Catalog Card Number: 64-8027 ISBN 0-12-012738-5 (alk. paper) Printed in the United States of America 90 91 92 93 9 8 7 6 5 4 3 2 1 CONTRIBUTORS Numbers in parentheses indicate the pages on which the authors' contributions begin. J. A. De Abreu-Garcia (211), Department of Electrical Engineering, The University of Akron, Akron, Ohio 44325 Itzhack Y. Bar-Itzhack (369), Department of Aerospace Engineering, Technion-Israel Institute of Technology, Haifa, 32000 Israel Kenneth R. Boff (41), United States Air Force, Armstrong Aerospace Medical Re- search Laboratory, Wright Patterson Air Force Base, Ohio 43455 William J. Cody (41), Search Technology, Inc., Norcross, Georgia 30092 Douglas G. De Wolf (307), Hughes Aircraft Company, Los Angeles, California 90009 Paul R. Frey (41), Search Technology, Inc., Norcross, Georgia 30092 T. T. Hartley (211), Department of Electrical Engineering, The University of Akron, Akron, Ohio 44325 George Meyer (1), NASA Ames Research Center, Moffett Field, California 94035 William B. Rouse (41), Search Technology, Inc., Norcross, Georgia 30092 Jcsef Shinar (153), Faculty of Aerospace Engineering, Technion-Israel Institute of Technology, Haifa, 32000 Israel P. F. Singer (273), Hughes Aircraft Company, El Segundo, California 90245 G. Allan Smith (1), Department of Electrical Engineering, Yale University, New Haven, Connecticut 06520 D. D. Sworder (273), Department of AMES, University of California, San Diego, La Jolla, California 92093 Hendrikus G. Visser (153), Faculty of Aerospace Engineering, Delft University of Technology, Delft, The Netherlands Stephen A. Whitmore (101), NASA Ames Research Center, Moffett Field, California 94035 Vll PREFACE In the 1940s military and civil aircraft were relatively simple and uncomplicated, as were their avionics systems. The intervening period and the last decade in particular have witnessed a tremendous growth in the capability and performance of aircraft and their avionics systems. In military aircraft the trend is toward future aircraft designs which will include significant nonlinear features in their aerody- namic and propulsion characteristics; in addition, they may be required to operate over extreme flight envelopes with implications for advanced automatic or semiau- tomatic flight control systems. Parallel advances are occurring in military aircraft avionics systems. Such aircraft as the ATF (Advanced Tactical Fighter) will have the computing power of three Cray supercomputers on board, and very necessarily so. Military aircraft sensor systems are becoming increasingly more powerful and their sensor data is being "fused." Current advanced trends include "smart aircraft skins," wherein the sensor systems might actually become an integral part of the aircraft skin. Other advanced trends of very impressive proportions are also occurring. Separately, in commercial aircraft, triply redundant inertial guidance systems have now been standard for almost two decades. Integrated GPS (Global Positioning Satellite) and AHARS (Attitude and Heading Reference Systems) seem to be an eventual certainty. The "glass cockpit," wherein display devices are multifunctional, is now a very significant reality. The MLS (Microwave Landing System), a very high precision capability landing system which is capable of category 3, zero-zero (visibility) landings and which has been aborning for over two decades, starting with the deliberations of RTCA/SC-117 (Radio Technical Com- mission for Aeronautics/Special Committee —117), seems to be headed for eventual, albeit delayed, introduction into commercial aviation. All these trends and many more make it most appropriate to devote a theme volume to "Advances in Aeronautical Systems Dynamics and Control," the theme for this volume in this Academic Press series. The first contribution, "Aircraft Automatic Flight Control System with Model ix x PREFACE Inversion," by G. Allan Smith and George Meyer, lays a foundation for a rather powerfully capable approach to aircraft trajectory control by the technique of inverse-model follower control systems. The basic idea behind the inverse-model follower is to embed an inverse model of the aircraft force and moment generating processes into the control system. The series combination of this inverse model provides the controls—aircraft control surface deflections, throttle, and thrust angle for aircraft, where applicable—necessary to produce the commanded acceleration input in response to a commanded trajectory acceleration input. A feedback control loop around this open-loop feed-forward control then results in an overall closely linear system which can compensate for model uncertainty and external disturbances. Of course, many questions arise as a result of all this, and this first contribution is devoted to answering such questions. Because of the fundamental importance of advanced aircraft trajectory capabilities, particularly in military aircraft, this is a most appropriate contribution with which to begin this volume. The next contribution, "Information Systems for Supporting Design of Complex Human-Machine Systems," by W. B. Rouse, W. J. Cody, K. R. Boff, and P. R. Frey, is concerned with the design of complex systems and how information systems can support the design process. With particular reference to the introductory comments for this preface, it is eminently clear that the design process for modern aeronautical systems is becoming an increasingly elaborate and challenging process. Indeed, the design decision process is a distributed process, typically across temporal, organi- zational, geographic, and disciplinary attributes. Further, for complex aeronautical systems, design decisions emerge both from individuals' activities as well as from group processes when individuals collaborate. Further, in the military aircraft area, the design process involves a continual iteration with respect to operational requirements, which it seems are in a constant state of flux. In addition, national politics have a very heavy influence on the design process as a number of specific aircraft system designs have clearly manifested. In the area of commercial aircraft, continual iterations with the customer community on the international scene have a heavy influence on the design process. In any event, this contribution which treats comprehensively the many issues involved in the design of complex human- machine systems, namely aircraft, is an essential element of this volume. Recent advances in aircraft performance and maneuver capability have dramati- cally complicated the problem of flight control augmentation. With increasing regularity, aircraft system designs require that aerodynamic parameters derived from pneumatic measurements be used as control system feedbacks. These require- ments necessitate that pneumatic data be measured with accuracy and fidelity. To date this has been a difficult task. The primary difficulty in obtaining high frequency pressure measurements is pressure distortion due to frictional attenuation and pneumatic resonance within the sensing system. Typically, most of the distortion occurs within the pneumatic tubing used to transmit pressure impulses from the surface of the aircraft to the measurement transducer. The next contribution, "Formulation of a Minimum Variance Decon volution Technique for Compensation PREFACE xi of Pneumatic Distortion in Pressure Sensing Devices," by Stephen A. Whitmore, presents techniques for achieving essential accuracy and fidelity in these pneumatic sensor systems and, because of the fundamental importance of this issue in modern aircraft, constitutes an essential element of this volume. One of the fundamental tasks in modern military aircraft is the interception of adversary aircraft with the essential objective of disrupting a hostile mission. The next contribution, "Synthesis and Validation of Feedback Guidance Laws for Air- to-Air Interceptions," by Josef Shinar and Hendricks G. Visser, provides an in- depth analysis of these issues and powerful and practically implementable techniques for guidance laws for air-to-air interceptions. Because of the rather comprehensive nature of this contribution, it will be an important source reference for workers in this field for years to come, and, as such, it constitutes an essential element of this volume. Real-time simulation of aeronautical systems is fundamental in the analysis, design, and testing of today's increasingly conplex aeronautical systems. Perhaps more important is the fact that simulation, including 3-D vision and motion simulation techniques, is an essential element in pilot training for both commercial and military aircraft. For instance, imagine, if you will, the first time the Boeing 747 airplane was flown, the huge significance of this event, and the absolute requirement that it be a completely successful flight. This is a classic example of the enormous significance of adequately valid real-time simulation techniques. The next contri- bution, "Multistep Matrix Integrators for Real-Time Simulation," by J. A. De Abreu-Garcia and T. T. Hartley, is a comprehensive treatment of issues which are of fundamental significance in achieving faithful real-time simulation results for both linear and nonlinear systems. Training simulators have achieved such a high level of capability that experienced pilots have felt the stresses and strains of flying under actual conditions. They have played a key role in the design of every single aircraft in modern times, particularly their cockpit instrumentation. Clearly, this contribution is also an essential element of this volume. An essential characteristic of all modern aeronautical systems is their avionics system, which is composed of many elements, in particular sensor systems. The matter of sensor systems signal processing and, in particular, electro-optical (EO) sensor systems signal processing is of particular significance and a continual challenge for military aircraft. There are many aspects of this problem including target dynamics, stochastic processes, system modeling, and others. In a rather remarkably comprehensive treatment of the basic and applied aspects of this problem, the next contribution, 'The Role of Image Interpretation in Tracking and Guidance," by D. D. Sworder and P. F. Singer, provides an excellent articulation of the many issues in this broad problem area. Because of the increasing pervasiveness of the issues treated in this contribution, in particular, with the increasing trend to the requisite implementation of "Smart" EO systems (trackers), this contribution plays a rather fundamental role in the overall contents of this volume. Parameter estimation in the presence of a stochastic environment has been a Xll PREFACE problem of theoretical interest for about three decades. Over the past decade, however, it has been of increasing applied interest in various advanced aeronautical systems. Examples have included parameter estimation in VSTOL aircraft, guid- ance system parameter estimates, and other issues. More generally, in aerospace systems the requirement for parameter estimation has, in some cases, resulted in extremely challenging and significant modeling issues. For example, the MX guidance system requires approximately a 90 element state vector, and the Trident vehicle requires approximately a 130 element state vector in the overall vehicle and guidance system parameter estimation. The next contribution, "Continuous Time Parameter Estimation: Analysis Via a Limiting Ordinary Differential Equation," by Douglas G. Dewolf, presents an analysis of many of the fundamental analytical issues in this area and a number of new results of fundamental significance. Inertial navigation systems are now an integral part of the avionics suite of all commercial and military aircraft. Their operation on both aircraft have many common features. However, there are also distinctions. One of these, in the case of military aircraft and, in some cases, the air-to-ground missiles they might carry, is the requirement for in-flight alignment. In-flight alignment is required for military aircraft in some operational instances because of the requirement for instant takeoff or "scrambling" as it is sometimes called. The next contribution, "In-Flight Alignment of Inertial Navigation Systems," by Itzhack Y. Bar-Itzhack, concludes this volume with an in-depth treatment of the issues and techniques in this area. The authors are all to be commended for their superb contributions which will provide, in this volume, a unique and significant reference source for many years to come for practicing professionals as well as those involved with advancing the state of the art. AIRCRAFT AUTOMATIC FLIGHT CONTROL SYSTEM WITH MODEL INVERSION G. ALLAN SMITH Electrical Engineering Department Yale University New Haven, Connecticut GEORGE MEYER NASA Ames Research Center Moffett Field, California NOMENCLATURE 2 I. INTRODUCTION 5 II. HISTORICAL BACKGROUND 6 III. CONTROL SYSTEM CONCEPT 8 IV. CONTROL SYSTEM IMPLEMENTATION 11 A. COMMAND SECTION 11 B. CONTROL SECTION 11 V. MODEL INVERSION PROCESS 13 VI. SIMULATION RESULTS 20 A. VERTICAL-ATTITUDE MANEUVERING 21 B. TRANSITION RUN FROM FORWARD FLIGHT TO HOVER 24 C. OTHER TRAJECTORIES 27 VII. ONGOING RESEARCH 27 VIII. CONCLUSIONS 28 APPENDIX A. COMMAND SECTION AND REGULATOR SECTION DESIGN 30 APPENDIX B. MATHEMATICAL DETAILS 35 REFERENCES 39 CONTROL AND DYNAMIC SYSTEMS, VOL. 38 1 G. ALLAN SMITH AND GEORGE MEYER NOMENCLATURE A aircraft acceleration vector Ac smooth commanded acceleration vector Ai rough commanded acceleration vector EF force equations error vector EM moment equations error vector Ε (θ) elementary direction cosine matrix for rotation about the second axis 2 through an angle Θ, similar notation for other angles and axes, where [cos Θ 0 -sin Θ] Ε (θ)= 0 1 0 2 |_ sin Θ 0 cos 0J F force vector acting on aircraft in Earth reference axes F force vector acting on aircraft in body axes b G gravity vector J aircraft moment of inertia matrix, where 0 XX J = 0 Iyy 0 *xz " ^ζζ. m aircraft mass moment vector acting on aircraft in body axes M b aircraft position vector R smooth commanded position vector Rc rough commanded position vector Ri STOL short takeoff and landing
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