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Author: National Aeronautics and Space Adm Nasa Publisher: Independently Published ISBN: 9781723726651 Category : Science Languages : en Pages : 38
Book Description
Near real-time stability and control derivative extraction is required to support flight demonstration of Intelligent Flight Control System (IFCS) concepts being developed by NASA, academia, and industry. Traditionally, flight maneuvers would be designed and flown to obtain stability and control derivative estimates using a postflight analysis technique. The goal of the IFCS concept is to be able to modify the control laws in real time for an aircraft that has been damaged in flight. In some IFCS implementations, real-time parameter identification (PID) of the stability and control derivatives of the damaged aircraft is necessary for successfully reconfiguring the control system. This report investigates the usefulness of Prescribed Simultaneous Independent Surface Excitations (PreSISE) to provide data for rapidly obtaining estimates of the stability and control derivatives. Flight test data were analyzed using both equation-error and output-error PID techniques. The equation-error PID technique is known as Fourier Transform Regression (FTR) and is a frequency-domain real-time implementation. Selected results were compared with a time-domain output-error technique. The real-time equation-error technique combined with the PreSISE maneuvers provided excellent derivative estimation in the longitudinal axis. However, the PreSISE maneuvers as presently defined were not adequate for accurate estimation of the lateral-directional derivatives.Moes, Timothy R. and Smith, Mark S. and Morelli, Eugene A.Armstrong Flight Research Center; Langley Research CenterAUTOMATIC CONTROL; FLIGHT CONTROL; REAL TIME OPERATION; CONTROL SYSTEMS DESIGN; AIRCRAFT CONTROL; DAMAGE; PARAMETER IDENTIFICATION; AIRCRAFT MANEUVERS; AIRCRAFT STABILITY; ERROR ANALYSIS; FOURIER TRANSFORMATION; TIME DOMAIN ANALYSIS
Author: National Aeronautics and Space Adm Nasa Publisher: Independently Published ISBN: 9781723726651 Category : Science Languages : en Pages : 38
Book Description
Near real-time stability and control derivative extraction is required to support flight demonstration of Intelligent Flight Control System (IFCS) concepts being developed by NASA, academia, and industry. Traditionally, flight maneuvers would be designed and flown to obtain stability and control derivative estimates using a postflight analysis technique. The goal of the IFCS concept is to be able to modify the control laws in real time for an aircraft that has been damaged in flight. In some IFCS implementations, real-time parameter identification (PID) of the stability and control derivatives of the damaged aircraft is necessary for successfully reconfiguring the control system. This report investigates the usefulness of Prescribed Simultaneous Independent Surface Excitations (PreSISE) to provide data for rapidly obtaining estimates of the stability and control derivatives. Flight test data were analyzed using both equation-error and output-error PID techniques. The equation-error PID technique is known as Fourier Transform Regression (FTR) and is a frequency-domain real-time implementation. Selected results were compared with a time-domain output-error technique. The real-time equation-error technique combined with the PreSISE maneuvers provided excellent derivative estimation in the longitudinal axis. However, the PreSISE maneuvers as presently defined were not adequate for accurate estimation of the lateral-directional derivatives.Moes, Timothy R. and Smith, Mark S. and Morelli, Eugene A.Armstrong Flight Research Center; Langley Research CenterAUTOMATIC CONTROL; FLIGHT CONTROL; REAL TIME OPERATION; CONTROL SYSTEMS DESIGN; AIRCRAFT CONTROL; DAMAGE; PARAMETER IDENTIFICATION; AIRCRAFT MANEUVERS; AIRCRAFT STABILITY; ERROR ANALYSIS; FOURIER TRANSFORMATION; TIME DOMAIN ANALYSIS
Author: Roger Larsson Publisher: Linköping University Electronic Press ISBN: 9176850706 Category : Science Languages : en Pages : 326
Book Description
With the demand for more advanced fighter aircraft, relying on unstable flight mechanical characteristics to gain flight performance, more focus has been put on model-based system engineering to help with the design work. The flight control system design is one important part that relies on this modeling. Therefore, it has become more important to develop flight mechanical models that are highly accurate in the whole flight envelope. For today’s modern fighter aircraft, the basic flight mechanical characteristics change between linear and nonlinear as well as stable and unstable as an effect of the desired capability of advanced maneuvering at subsonic, transonic and supersonic speeds. This thesis combines the subject of system identification, which is the art of building mathematical models of dynamical systems based on measurements, with aeronautical engineering in order to find methods for identifying flight mechanical characteristics. Here, some challenging aeronautical identification problems, estimating model parameters from flight-testing, are treated. Two aspects are considered. The first is online identification during flight-testing with the intent to aid the engineers in the analysis process when looking at the flight mechanical characteristics. This will also ensure that enough information is available in the resulting test data for post-flight analysis. Here, a frequency domain method is used. An existing method has been developed further by including an Instrumental Variable approach to take care of noisy data including atmospheric turbulence and by a sensor-fusion step to handle varying excitation during an experiment. The method treats linear systems that can be both stable and unstable working under feedback control. An experiment has been performed on a radio-controlled demonstrator aircraft. For this, multisine input signals have been designed and the results show that it is possible to perform more time-efficient flight-testing compared with standard input signals. The other aspect is post-flight identification of nonlinear characteristics. Here the properties of a parameterized observer approach, using a prediction-error method, are investigated. This approach is compared with four other methods for some test cases. It is shown that this parameterized observer approach is the most robust one with respect to noise disturbances and initial offsets. Another attractive property is that no user parameters have to be tuned by the engineers in order to get the best performance. All methods in this thesis have been validated on simulated data where the system is known, and have also been tested on real flight test data. Both of the investigated approaches show promising results.
Author: Eugene Morelli Publisher: Sunflyte Enterprises ISBN: 9780997430615 Category : Technology & Engineering Languages : en Pages : 618
Book Description
This book provides a comprehensive overview of both the theoretical underpinnings and the practical application of aircraft modeling based on experimental data also known as aircraft system identification. Much of the material presented comes from the authors own extensive research and teaching activities at the NASA Langley Research Center, and is based on real-world applications of system identification to aircraft. The book uses actual flight-test and wind-tunnel data for case studies and examples, and is a valuable resource for researchers and practicing engineers, as well as a textbook for postgraduate and senior-level courses. [...] The methods and algorithms explained in the book are implemented in a NASA software toolbox called SIDPAC (System IDentification Programs for AirCraft). SIDPAC is written in MATLAB®, and is available by request from NASA Langley Research Center. SIDPAC is composed of many different tools that implement a wide variety of approaches explained fully in the book. These tools can be readily applied to solve aircraft system identification problems.
Author: Alejandro Sobron Publisher: Linköping University Electronic Press ISBN: 9176852202 Category : Languages : en Pages : 130
Book Description
Downscaled physical models, also referred to as subscale models, have played an essential role in the investigation of the complex physics of flight until the recent disruption of numerical simulation. Despite the fact that improvements in computational methods are slowly pushing experimental techniques towards a secondary role as verification or calibration tools, real-world testing of physical prototypes still provides an unmatched confidence. Physical models are very effective at revealing issues that are sometimes not correctly identified in the virtual domain, and hence can be a valuable complement to other design tools. But traditional wind-tunnel testing cannot always meet all of the requirements of modern aeronautical research and development. It is nowadays too expensive to use these scarce facilities to explore different design iterations during the initial stages of aircraft development, or to experiment with new and immature technologies. Testing of free-flight subscale models, referred to as Subscale Flight Testing (SFT), could offer an affordable and low-risk alternative for complementing conventional techniques with both qualitative and quantitative information. The miniaturisation of mechatronic systems, the advances in rapid-prototyping techniques and power storage, as well as new manufacturing methods, currently enable the development of sophisticated test objects at scales that were impractical some decades ago. Moreover, the recent boom in the commercial drone industry has driven a quick development of specialised electronics and sensors, which offer nowadays surprising capabilities at competitive prices. These recent technological disruptions have significantly altered the cost-benefit function of SFT and it is necessary to re-evaluate its potential in the contemporary aircraft development context. This thesis aims to increase the comprehension and knowledge of the SFT method in order to define a practical framework for its use in aircraft design; focusing on low-cost, short-time solutions that don’t require more than a small organization and few resources. This objective is approached from a theoretical point of view by means of an analysis of the physical and practical limitations of the scaling laws; and from an empirical point of view by means of field experiments aimed at identifying practical needs for equipment, methods, and tools. A low-cost data acquisition system is developed and tested; a novel method for semi-automated flight testing in small airspaces is proposed; a set of tools for analysis and visualisation of flight data is presented; and it is also demonstrated that it is possible to explore and demonstrate new technology using SFT with a very limited amount of economic and human resources. All these, together with a theoretical review and contextualisation, contribute to increasing the comprehension and knowledge of the SFT method in general, and its potential applications in aircraft conceptual design in particular.
Author: Babin, Marcel Publisher: UNESCO ISBN: 9231040421 Category : Nature Languages : en Pages : 880
Book Description
The proliferation of harmful phytoplankton in marine ecosystems can cause massive fish kills, contaminate seafood with toxins, impact local and regional economies and dramatically affect ecological balance. Real-time observations are essential for effective short-term operational forecasting, but observation and modelling systems are still being developed. This volume provides guidance for developing real-time and near real-time sensing systems for observing and predicting plankton dynamics, including harmful algal blooms, in coastal waters. The underlying theory is explained and current trends in research and monitoring are discussed.Topics covered include: coastal ecosystems and dynamics of harmful algal blooms; theory and practical applications of in situ and remotely sensed optical detection of microalgal distributions and composition; theory and practical applications of in situ biological and chemical sensors for targeted species and toxin detection; integrated observing systems and platforms for detection; diagnostic and predictive modelling of ecosystems and harmful algal blooms, including data assimilation techniques; observational needs for the public and government; and future directions for research and operations.
Author: Douglas A. Joyce Publisher: ISBN: 9781626830196 Category : Research aircraft Languages : en Pages : 409
Book Description
The X-31 Enhanced Fighter Maneuverability Demonstrator was unique among experimental aircraft. A joint effort of the United States and Germany, the X-31 was the only X-plane to be designed, manufactured, and flight tested as an international collaboration. It was also the only X-plane to support two separate test programs conducted years apart, one administered largely by NASA and the other by the U.S. Navy, as well as the first X-plane ever to perform at the Paris Air Show. Flying Beyond the Stall begins by describing the government agencies and private-sector industries involved in the X-31 program, the genesis of the supermaneuverability concept and its initial design breakthroughs, design and fabrication of two test airframes, preparation for the X-31's first flight, and the first flights of Ship #1 and Ship #2. Subsequent chapters discuss envelope expansion, handling qualities (especially at high angles of attack), and flight with vectored thrust. The book then turns to the program's move to NASA's Dryden Flight Research Center and actual flight test data. Additional tasking, such as helmet-mounted display evaluations, handling quality studies, aerodynamic parameter estimation, and a "tailless" study are also discussed.The book describes how, in the aftermath of a disastrous accident with Ship #1 in 1995, Ship #2 was prepared for its outstanding participation in the Paris Air Show. The aircraft was then shipped back to Edwards AFB and put into storage until the late 1990s, when it was refurbished for participation in the U. S. Navy's VECTOR program. The book ends with a comprehensive discussion of lessons learned and includes an Appendix containing detailed information.
Author: National Research Council Publisher: National Academies Press ISBN: 0309056888 Category : Transportation Languages : en Pages : 221
Book Description
Adverse aircraft-pilot coupling (APC) events include a broad set of undesirable and sometimes hazardous phenomena that originate in anomalous interactions between pilots and aircraft. As civil and military aircraft technologies advance, interactions between pilots and aircraft are becoming more complex. Recent accidents and other incidents have been attributed to adverse APC in military aircraft. In addition, APC has been implicated in some civilian incidents. This book evaluates the current state of knowledge about adverse APC and processes that may be used to eliminate it from military and commercial aircraft. It was written for technical, government, and administrative decisionmakers and their technical and administrative support staffs; key technical managers in the aircraft manufacturing and operational industries; stability and control engineers; aircraft flight control system designers; research specialists in flight control, flying qualities, human factors; and technically knowledgeable lay readers.
Author: National Aeronautics and Space Adm Nasa
Author: National Aeronautics and Space Adm Nasa
Author: Mark S. Smith
Author: Roger Larsson
Author: Eugene Morelli
Author: Alejandro Sobron
Author: 
Author: Babin, Marcel
Author: Douglas A. Joyce
Author: National Research Council
Author: Lawrence W. Taylor