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Book Research in Nonlinear Flight Control for Tiltrotor Aircraft Operating in the Terminal Area

Download or read book Research in Nonlinear Flight Control for Tiltrotor Aircraft Operating in the Terminal Area written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-10-26 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: The research during the first year of the effort focused on the implementation of the recently developed combination of neural net work adaptive control and feedback linearization. At the core of this research is the comprehensive simulation code Generic Tiltrotor Simulator (GTRS) of the XV-15 tilt rotor aircraft. For this research the GTRS code has been ported to a Fortran environment for use on PC. The emphasis of the research is on terminal area approach procedures, including conversion from aircraft to helicopter configuration. This report focuses on the longitudinal control which is the more challenging case for augmentation. Therefore, an attitude command attitude hold (ACAH) control augmentation is considered which is typically used for the pitch channel during approach procedures. To evaluate the performance of the neural network adaptive control architecture it was necessary to develop a set of low order pilot models capable of performing such tasks as, follow desired altitude profiles, follow desired speed profiles, operate on both sides of powercurve, convert, including flaps as well as mastangle changes, operate with different stability and control augmentation system (SCAS) modes. The pilot models are divided in two sets, one for the backside of the powercurve and one for the frontside. These two sets are linearly blended with speed. The mastangle is also scheduled with speed. Different aspects of the proposed architecture for the neural network (NNW) augmented model inversion were also demonstrated. The demonstration involved implementation of a NNW architecture using linearized models from GTRS, including rotor states, to represent the XV-15 at various operating points. The dynamics used for the model inversion were based on the XV-15 operating at 30 Kts, with residualized rotor dynamics, and not including cross coupling between translational and rotational states. The neural network demonstrated ACAH control under various circumstances. Future effort

Book The History of the XV 15 Tilt Rotor Research Aircraft

Download or read book The History of the XV 15 Tilt Rotor Research Aircraft written by Martin D. Maisel and published by . This book was released on 2000 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Nonlinear Analysis and Synthesis Techniques for Aircraft Control

Download or read book Nonlinear Analysis and Synthesis Techniques for Aircraft Control written by Declan Bates and published by Springer. This book was released on 2007-10-04 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the first book to focus on the use of nonlinear analysis and synthesis techniques for aircraft control. It is also the first book to address in detail closed-loop control problems for aircraft "on-ground" – i.e. speed and directional control of aircraft before take-off and after touch down. The book will be of interest to engineers, researchers, and students in control engineering, and especially aircraft control.

Book A Study of Nonlinear Flight Control System Designs

Download or read book A Study of Nonlinear Flight Control System Designs written by Lijun Tian and published by . This book was released on 1999 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis discusses both normal aircraft flight control where the control surfaces are the primary effectors, and unconventional emergency flight control by engines only. It has long been realized that nonlinearity in aircraft dynamics is a prominent consideration in design of high-performance conventional flight control systems. The engine-only flight control problem also faces strong nonlinearity, although due to different reasons. A nonlinear predictive control method and an approximate receding-horizon control method are used for normal and engine-only flight control system designs for an F-18 aircraft. The comparison of the performance with that of linear flight controllers provides some insight into when nonlinear controllers may render a much improved performance. The concept of nonlinear flight control system design is extended to output tracking control problem. The capability of the nonlinear controller to stabilize the aircraft and accomplish output tracking control for non-minimum phase system is successfully demonstrated. Numerical simulation results of longitudinal motion based on two typical flight conditions for an F-18 aircraft is presented to illustrate some of these aspects. It is suggested in this thesis that nonlinear flight control system design, particularly the engine-only controller design and output tracking control design for non-minimum phase system by using a nonlinear method is more effective for the highly nonlinear environment. The recently developed continuous-time predictive control approach and an approximate receding-horizon control method are shown to be effective methods in the situation while the conventional linear or popular nonlinear control designs are either ineffective or inapplicable.

Book An Investigation of Nonlinear Controller for Propulsion Controlled Aircraft

Download or read book An Investigation of Nonlinear Controller for Propulsion Controlled Aircraft written by National Aeronautics and Space Adm Nasa and published by . This book was released on 2018-10-22 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aircraft control systems are usually very reliable because of redundancy and multiple control surfaces. However, there are rare occasions when potentially disastrous flight control system failures do occur. At such times, the use of appropriate modulation of engine thrust to stabilize the aircraft may be the only chance of survival for the people aboard. In several cases where complete loss of control systems has occurred in multi-engine aircraft, pilots used the propulsion system to regain limited control of the aircraft with various degrees of success. In order to evaluate the feasibility of using only engine thrust modulation for emergency backup flight control, the NASA Dryden Flight Research Center has been conducting a series of analytical studies and flight tests on several different types of aircraft in a propulsion controlled aircraft (PCA) program. Simulation studies have included B-720, B-727, MD-11, C-402, C-17, F-18, and F-15, and flight tests have included B-747, B-777, MD-11, T-39, Lear 24, F-18, F-15, T-38, and PA-30. One objective was to determine the degree of control available with manual manipulation (open-loop) of the engine throttles. Flight tests and simulations soon showed that a closed loop controller could improve the chances of making a safe runway landing. The major work to date has concentrated on three aircraft (F-15, F-18, and the MD-11). Successful landings using PCA controllers were performed on the F-15 and MD-11 without the use of control surfaces. During the course of the research, some unique challenges have been identified. Compared to the conventional flight control surfaces, the engines are slow and have limited control effectiveness. Hence the ability of the system to promptly respond to aerodynamic changes is limited. Consequently, many nonlinear effects, which are easily accommodated by a conventional flight control system, become significant issues in the design of an effective controller when the engines are used as the o...

Book A Direct Application of the Non Linear Inverse Transformation Flight Control System Design on a Stovl Aircraft

Download or read book A Direct Application of the Non Linear Inverse Transformation Flight Control System Design on a Stovl Aircraft written by National Aeronautics and Space Adm Nasa and published by . This book was released on 2018-10-23 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: The nonlinear inverse transformation flight control system design method is applied to the Lockheed Ft. Worth Company's E-7D short takeoff and vertical land (STOVL) supersonic fighter/attack aircraft design with a modified General Electric F110 engine which has augmented propulsive lift capability. The system is fully augmented to provide flight path control and velocity control, and rate command attitude hold for angular axes during the transition and hover operations. In cruise mode, the flight control system is configured to provide direct thrust command, rate command attitude hold for pitch and roll axes, and sideslip command with turn coordination. A control selector based on the nonlinear inverse transformation method is designed specifically to be compatible with the propulsion system's physical configuration which has a two dimensional convergent-divergent aft nozzle, a vectorable ventral nozzle, and a thrust augmented ejector. The nonlinear inverse transformation is used to determine the propulsive forces and nozzle deflections, which in combination with the aerodynamic forces and moments (including propulsive induced contributions), and gravitational force, are required to achieve the longitudinal and vertical acceleration commands. The longitudinal control axes are fully decoupled within the propulsion system's performance envelope. A piloted motion-base flight simulation was conducted on the Vertical Motion Simulator (VMS) at NASA Ames Research Center to examine the handling qualities of this design. Based on results of the simulation, refinements to the control system have been made and will also be covered in the report. Chung, W. W. and Mcneill, W. E. and Stortz, M. W. Ames Research Center RTOP 533-02-37...

Book Adaptive Compensation of Nonlinear Actuators for Flight Control Applications

Download or read book Adaptive Compensation of Nonlinear Actuators for Flight Control Applications written by Dipankar Deb and published by Springer. This book was released on 2022-07-24 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a basic understanding of adaptive control and its applications in Flight control. It discusses the designing of an adaptive feedback control system and analyzes this for flight control of linear and nonlinear aircraft models using synthetic jet actuators. It also discusses control methodologies and the application of control techniques which will help practicing flight control and active flow control researchers. It also covers modelling and control designs which will also benefit researchers from the background of fluid mechanics and health management of actuation systems. The unique feature of this book is characterization of synthetic jet actuator nonlinearities over a wide range of angles of attack, an adaptive compensation scheme for such nonlinearities, and a systematic framework for feedback control of aircraft dynamics with synthetic jet actuators.

Book Flight Experiments to Improve Terminal Area Operations

Download or read book Flight Experiments to Improve Terminal Area Operations written by Seymour Salmirs and published by . This book was released on 1978 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Exploratory Studies in Generalized Predictive Control for Active Aeroelastic Control of Tiltrotor Aircraft

Download or read book Exploratory Studies in Generalized Predictive Control for Active Aeroelastic Control of Tiltrotor Aircraft written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-05-31 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Aeroelasticity Branch at NASA Langley Research Center has a long and substantive history of tiltrotor aeroelastic research. That research has included a broad range of experimental investigations in the Langley Transonic Dynamics Tunnel (TDT) using a variety of scale models and the development of essential analyses. Since 1994, the tiltrotor research program has been using a 1/5-scale, semispan aeroelastic model of the V-22 designed and built by Bell Helicopter Textron Inc. (BHTI) in 1981. That model has been refurbished to form a tiltrotor research testbed called the Wing and Rotor Aeroelastic Test System (WRATS) for use in the TDT. In collaboration with BHTI, studies under the current tiltrotor research program are focused on aeroelastic technology areas having the potential for enhancing the commercial and military viability of tiltrotor aircraft. Among the areas being addressed, considerable emphasis is being directed to the evaluation of modern adaptive multi-input multi- output (MIMO) control techniques for active stability augmentation and vibration control of tiltrotor aircraft. As part of this investigation, a predictive control technique known as Generalized Predictive Control (GPC) is being studied to assess its potential for actively controlling the swashplate of tiltrotor aircraft to enhance aeroelastic stability in both helicopter and airplane modes of flight. This paper summarizes the exploratory numerical and experimental studies that were conducted as part of that investigation.Kvaternik, Raymond G. and Juang, Jer-Nan and Bennett, Richard L.Langley Research CenterCONTROL SYSTEMS DESIGN; ACTIVE CONTROL; HELICOPTERS; AEROELASTICITY; AIRCRAFT CONTROL; MIMO (CONTROL SYSTEMS); STABILITY AUGMENTATION; V-22 AIRCRAFT; VIBRATION DAMPING

Book Nonclassical Flight Control for Unhealthy Aircraft

Download or read book Nonclassical Flight Control for Unhealthy Aircraft written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-09 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research set out to investigate flight control of aircraft which has sustained damage in regular flight control effectors, due to jammed control surfaces or complete loss of hydraulic power. It is recognized that in such an extremely difficult situation unconventional measures may need to be taken to regain control and stability of the aircraft. Propulsion controlled aircraft (PCA) concept, initiated at the NASA Dryden Flight Research Center. represents a ground-breaking effort in this direction. In this approach, the engine is used as the only flight control effector in the rare event of complete loss of normal flight control system. Studies and flight testing conducted at NASA Dryden have confirmed the feasibility of the PCA concept. During the course of this research (March 98, 1997 to November 30, 1997), a comparative study has been done using the full nonlinear model of an F-18 aircraft. Linear controllers and nonlinear controllers based on a nonlinear predictive control method have been designed for normal flight control system and propulsion controlled aircraft. For the healthy aircraft with normal flight control, the study shows that an appropriately designed linear controller can perform as well as a nonlinear controller. On the other hand. when the normal flight control is lost and the engine is the only available means of flight control, a nonlinear PCA controller can significantly increase the size of the recoverable region in which the stability of the unstable aircraft can be attained by using only thrust modulation. The findings and controller design methods have been summarized in an invited paper entitled. Lu, Ping Armstrong Flight Research Center NCC4-109...

Book NASA Technical Paper

Download or read book NASA Technical Paper written by and published by . This book was released on 1979 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Robust Nonlinear Aircraft Flight Control

Download or read book Robust Nonlinear Aircraft Flight Control written by James M. Buffington and published by . This book was released on 2001 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: This project addresses the development of both control synthesis and analysis methods for affordable, highly integrated nonlinear aircraft control systems through basic research and development of control science and dynamical systems theory. The technical approach is to explore the following three primary research areas: (1) stability analysis, (2) robust nonlinear control, and (3) robust reconfigurable control. The stability analysis task assesses robustness of a baseline flight control system. The analysis results are used to develop on-board model and control allocation requirements for the other two tasks. The robust nonlinear control task includes development of compact on-board model and dynamic control allocation synthesis methods. The reconfigurable control design task includes development of an on-board model update synthesis method. The main accomplishment for the stability analysis task is using structured singular value analysis to formalize control allocation stability implications and to specify stability and control derivative accuracy requirements for on-board model synthesis. The main accomplishments for the robust nonlinear control design task are development of a dynamic control allocation formulation and development of a compact on-board model synthesis method. The main accomplishment for the robust reconfigurable control design task is the development of an on-line learning method for on-board model updates to enhance the robustness of indirect adaptive flight control systems.

Book Scientific and Technical Aerospace Reports

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 702 pages. Available in PDF, EPUB and Kindle. Book excerpt: