HIGH ANGLE OF ATTACK MANEUVERING AND STABILIZATION CONTROL OF AIRCRAFT A THESIS SUBMITTED TO THE GRADUATE SCHOOL OF NATURAL AND APPLIED SCIENCES OF MIDDLE EAST TECHNICAL UNIVERSITY BY ÖZGÜR ATE ŞOĞLU IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN MECHANICAL ENGINEERING JULY 2007 Approval of the Thesis “HIGH ANGLE OF ATTACK MANEUVERING AND STABILIZATION CONTROL OF AIRCRAFT” Submitted by ÖZGÜR ATE ŞOĞLU in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Mechanical Engineering by, Prof. Dr. Canan ÖZGEN Dean, Graduate School of Natural and Applied Sciences __________________________ Prof. Dr. S. Kemal İDER Head of Department, Mechanical Engineering __________________________ Prof. Dr. M. Kemal ÖZGÖREN Supervisor, Mechanical Engineering Dept., METU __________________________ Examining Committee Members: Prof. Dr. Bülent E. PLAT İN (*) Mechanical Engineering Dept., METU __________________________ Prof. Dr. M. Kemal ÖZGÖREN (**) Mechanical Engineering Dept., METU __________________________ Prof. Dr. M. Kemal LEBLEB İCİOĞLU Electrical and Electronics Engineering Dept., METU __________________________ Prof. Dr. Tuna BALKAN Mechanical Engineering Dept., METU __________________________ Asst. Prof. Dr. Yakup ÖZKAZANÇ Electrical and Electronics Engineering Dept., HÜ __________________________ Date: __________________________ (*) Head of Examining Committee (**) Supervisor PLAGIARISM I hereby declare that all information in this document has been obtained and presented in accordance with academic rules and ethical conduct. I also declare that, as required by these rules and conduct, I have fully cited and referenced all material and results that are not original to this work. Name, Last Name : Özgür ATE ŞOĞLU Signature : iii ABSTRACT HIGH ANGLE OF ATTACK MANEUVERING AND STABILIZATION CONTROL OF AIRCRAFT ATE ŞOĞLU, Özgür Ph. D., Department of Mechanical Engineering Supervisor: Prof. Dr. M. Kemal ÖZGÖREN July 2007, 281 pages In this study, the implementation of modern control techniques, that can be used both for the stable recovery of the aircraft from the undesired high angle of attack flight state (stall) and the agile maneuvering of the aircraft in various air combat or defense missions, are performed. In order to accomplish this task, the thrust vectoring control (TVC) actuation is blended with the conventional aerodynamic controls. The controller design is based on the nonlinear dynamic inversion (NDI) control methodologies and the stability and robustness analyses are done by using robust performance (RP) analysis techniques. The control architecture is designed to serve both for the recovery from the undesired stall condition ( the stabilization controller ) and to perform desired agile maneuvering (the attitude controller ). The detailed modeling of the aircraft dynamics, aerodynamics, engines and thrust vectoring paddles, as well as the flight environment of the aircraft and the on-board sensors is performed. Within the iv control loop the human pilot model is included and the design of a fly-by-wire controller is also investigated. The performance of the designed stabilization and attitude controllers are simulated using the custom built 6 DoF aircraft flight simulation tool. As for the stabilization controller, a forced deep-stall flight condition is generated and the aircraft is recovered to stable and pilot controllable flight regimes from that undesired flight state. The performance of the attitude controller is investigated under various high angle of attack agile maneuvering conditions. Finally, the performances of the proposed controller schemes are discussed and the conclusions are made. Keywords: High Alpha Maneuvering, Thrust Vectoring Control (TVC), Nonlinear Inverse Dynamics (NID), Robust Performance (RP) Analysis, Human Pilot. v ÖZ UÇAKLARIN YÜKSEK HÜCUM AÇISINDA MANEVRA VE STAB İLİZASYON DENET İMİ ATE ŞOĞLU, Özgür Doktora, Makina Mühendisli ği Bölümü Tez Yöneticisi: Prof. Dr. M. Kemal ÖZGÖREN Temmuz 2007, 281 sayfa Bu çalı şmada, uçakların yüksek hücum açılarında denetimi için modern yöntemler kullanılarak denetleyici tasarımları gerçekle ştirilmi ştir. Denetleyiciler hem stabilizasyon hem de yönelim denetiminde kullanılabilecek yapıda tasarlanmı ştır. Tasarlanan denetleyiciler, uçakları istenmeden kar şıla şılan ve oldukça tehlikeli olabilecek yüksek hücum açılarındaki uçu şlardan kurtarmak ve pilot tarafından kolaylıkla denetlenebilecek kararlı uçu ş durumlarına getirmekte kullanılabildi ği gibi, aynı zamanda, sava ş ve savunma uçu şlarında yüksek hücum açılarında gerçekle ştirilen çevik manevraların denetiminde de kullanılabilmektedir. Denetim itki vektörü denetimi (İVD) yöntemi ile geleneksel aerodinamik kontrol eyleticileri harmanlanarak gerçekle ştirilmi ştir. Denetim tasarımında do ğrusal olmayan evrik dinamik (DOED) yöntemi kullanılmı ş ve dayanıklılık analizleri yapılmı ştır. Hava aracının dinami ği, aerodinami ği, motoru, itki yönlendirme pedalları, uçu ş ortamı ve üzerindeki algılayıcılar detaylı olarak modellenmi ş ve 6 vi serbestlik dereceli bir hava aracı uçu ş benzetimi sentezlenmi ştir. Bu modellere pilot modeli de eklenmi ş ve denetim yapılarının pilot modeli ile birlikte dayanıklılık analizleri yapılmı ştır. Stabilizasyon denetimi için hava aracı bilerek istenmeyen bir yüksek hücum açısında uçu ş durumuna itilmi ş ve buradan denetim yardımı ile kurtarılarak kararlı ve kolay denetlenebilir uçu ş rejimlerine çekilmi ştir. Yönelim denetiminin ba şarımı ise yüksek hücum açılarında yapılan farklı çevik manevra benzetimleri ile gösterilmi ştir. Gerçekle ştirilen benzetimlerin sonuçları incelenmi ş ve tasarlanan denetim yapılarının ba şarımları yorumlanmı ştır. Anahtar Kelimeler: Yüksek Hücum Açılarında Manevralar, İtki Vektörü Denetimi (İVD), Do ğrusal Olmayan Evrik Dinamik (DOED), Dayanıklılık Ba şarım Analizi, Pilot Modeli. vii In the Name of My Beloved Father viii ACKNOWLEDGMENTS Above all, I wish to express my sincere gratitude to my supervisor, Prof. Dr. M. Kemal ÖZGÖREN for his guidance, helpful suggestions, encouragements, valuable interaction and feedbacks throughout the study. I would also like to thank to my Thesis Supervising Committee members, Prof. Dr. Bülent E. PLAT İN and Prof. Dr. M. Kemal LEBLEB İCİOĞLU for their constructive comments and guidance throughout my study. Furthermore, I would like to thank to my thesis jury committee members Prof. Dr. Tuna BALKAN and Asst. Prof. Dr. Yakup ÖZKAZANÇ for their contributions. I would like to thank to my colleague Dr. Volkan NALBANTO ĞLU for his prompt comments and feedbacks, and also, my manager and colleagues and friends from Aselsan MGEO for their help and friendship. In addition, I am indebted to my family to form a part of my vision of life and teach me to do the things at my best rate. Also, I am thankful to my father, and his happy memory, to teach the strong, straight and joyful side of life from the mathematics point of view. Finally, my sincere gratitude is dedicated to the cosmological Prime Mover for giving me the inspiration to begin and the desire to conclude this thesis work. ix TABLE OF CONTENTS ABSTRACT.............................................................................................................. iv ÖZ ............................................................................................................................. vi ACKNOWLEDGMENTS ........................................................................................ ix TABLE OF CONTENTS........................................................................................... x LIST OF TABLES ..................................................................................................xiii LIST OF FIGURES ................................................................................................ xiv LIST OF SYMBOLS ............................................................................................xxiii LIST OF ABBREVIATIONS................................................................................ xxx CHAPTER 1. INTRODUCTION............................................................................................. 1 1.1. The Scope of the Study ........................................................................... 1 1.2. Controlling the Aircraft........................................................................... 2 1.2.1. Basic Flight Maneuvers............................................................... 4 1.2.2. Basic Flight Maneuvers for Fighters........................................... 6 1.3. The Fundamentals of Air Combat Maneuvers ...................................... 10 1.3.1. Basic Air Combat (Fighter) Maneuvers .................................... 15 1.3.2. Basic Air Combat Tactics.......................................................... 18 1.4. High Angle of Attack Aerodynamics.................................................... 21 1.5. High Angle of Attack Maneuvering Control ........................................ 26 1.5.1. Dynamic Inverse Controller Design.......................................... 35 x 1.5.1.1. 2-Time Scale Method.................................................. 37 1.5.1.2. Simplified Longitudinal Controller Example for an Aircraft ..................................................................................... 39 1.5.1.3. The Assignment of the Desired Dynamics.................. 41 1.5.1.4. The Basic Issues of Dynamic Inversion...................... 44 1.5.2. Stability and Robustness Analysis ...........................................