Download or read book Identification of Low Order Equivalent System Models from Flight Test Data 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 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: Identification of low order equivalent system dynamic models from flight test data was studied. Inputs were pilot control deflections, and outputs were aircraft responses, so the models characterized the total aircraft response including bare airframe and flight control system. Theoretical investigations were conducted and related to results found in the literature. Low order equivalent system modeling techniques using output error and equation error parameter estimation in the frequency domain were developed and validated on simulation data. It was found that some common difficulties encountered in identifying closed loop low order equivalent system models from flight test data could be overcome using the developed techniques. Implications for data requirements and experiment design were discussed. The developed methods were demonstrated using realistic simulation cases, then applied to closed loop flight test data from the NASA F-18 High Alpha Research Vehicle.Morelli, Eugene A.Langley Research CenterEXPERIMENT DESIGN; DYNAMIC MODELS; SYSTEM IDENTIFICATION; FLIGHT TESTS; DATA PROCESSING; FLIGHT CONTROL; DEFLECTION; AIRCRAFT PERFORMANCE; ERROR ANALYSIS; FLIGHT CHARACTERISTICS; FEEDBACK CONTROL

Download or read book Identification of Low Order Equivalent System Models from Flight Test Data written by Eugene A. Morelli and published by . This book was released on 2000 with total page 59 pages. Available in PDF, EPUB and Kindle. Book excerpt: Identification of low order equivalent system dynamic models from flight test data was studied. Inputs were pilot control deflections, and outputs were aircraft responses, so the models characterized the total aircraft response including bare airframe and flight control system. Theoretical investigations were conducted and related to results found in the literature. Low order equivalent system modeling techniques using output error and equation error parameter estimation in the frequency domain were developed and validated on simulation data. It was found that some common difficulties encountered in identifying closed loop low order equivalent system models from flight test data could be overcome using the developed techniques. Implications for data requirements and experiment design were discussed. The developed methods were demonstrated using realistic simulation cases, then applied to closed loop flight test data from the NASA F-18 High Alpha Research Vehicle.

Download or read book Closed Loop System Identification Experience for Flight Control Law and Flying Qualities Evaluation of a High Performance Fighter Aircraft written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-16 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper highlights some of the results and issues associated with estimating models to evaluate control law design methods and design criteria for advanced high performance aircraft. Experimental fighter aircraft such as the NASA-High Alpha Research Vehicle (HARV) have the capability to maneuver at very high angles of attack where nonlinear aerodynamics often predominate. HARV is an experimental F/A-18, configured with thrust vectoring and conformal actuated nose strakes. Identifying closed-loop models for this type of aircraft can be made difficult by nonlinearities and high order characteristics of the system. In this paper, only lateral-directional axes are considered since the lateral-directional control law was specifically designed to produce classical airplane responses normally expected with low-order, rigid-body systems. Evaluation of the control design methodology was made using low-order equivalent systems determined from flight and simulation. This allowed comparison of the closed-loop rigid-body dynamics achieved in flight with that designed in simulation. In flight, the On Board Excitation System was used to apply optimal inputs to lateral stick and pedals at five angles at attack : 5, 20, 30, 45, and 60 degrees. Data analysis and closed-loop model identification were done using frequency domain maximum likelihood. The structure of identified models was a linear state-space model reflecting classical 4th-order airplane dynamics. Input time delays associated with the high-order controller and aircraft system were accounted for in data preprocessing. A comparison of flight estimated models with small perturbation linear design models highlighted nonlinearities in the system and indicated that the closed-loop rigid-body dynamics were sensitive to input amplitudes at 20 and 30 degrees angle of attack. Murphy, Patrick C. Langley Research Center NASA/TM-1998-207995, NAS 1.15:207995 ...

Download or read book Estimation of Handling Qualities Parameters of the Tu 144 Supersonic Transport Aircraft from Flight Test Data written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-13 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: Low order equivalent system (LOES) models for the Tu-144 supersonic transport aircraft were identified from flight test data. The mathematical models were given in terms of transfer functions with a time delay by the military standard MIL-STD-1797A, "Flying Qualities of Piloted Aircraft," and the handling qualities were predicted from the estimated transfer function coefficients. The coefficients and the time delay in the transfer functions were estimated using a nonlinear equation error formulation in the frequency domain. Flight test data from pitch, roll, and yaw frequency sweeps at various flight conditions were used for parameter estimation. Flight test results are presented in terms of the estimated parameter values, their standard errors, and output fits in the time domain. Data from doublet maneuvers at the same flight conditions were used to assess the predictive capabilities of the identified models. The identified transfer function models fit the measured data well and demonstrated good prediction capabilities. The Tu-144 was predicted to be between level 2 and 3 for all longitudinal maneuvers and level I for all lateral maneuvers. High estimates of the equivalent time delay in the transfer function model caused the poor longitudinal rating. Curry, Timothy J. and Batterson, James G. (Technical Monitor) Langley Research Center NCC1-29; RTOP 537-08-23-21

Download or read book On Subscale Flight Testing written by Alejandro Sobron and published by Linköping University Electronic Press. This book was released on 2018-11-05 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Estimating Short period Dynamics Using an Extended Kalman Filter written by and published by . This book was released on 1990 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Advances in Swarm Intelligence written by Ying Tan and published by Springer. This book was released on 2012-06-13 with total page 631 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book and its companion volume, LNCS vols. 7331 and 7332, constitute the Proceedings of the Third International conference on Swarm Intelligence, ICSI 2012, held in Shenzhen, China in June 2012. The 145 full papers presented were carefully reviewed and selected from 247 submissions. The papers are organized in 27 cohesive sections covering all major topics of swarm intelligence research and developments.

Download or read book Rotorcraft System Identification written by and published by . This book was released on 1991 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Identification of Dynamic Systems Nonlinear analysis and manoeuvre design written by and published by . This book was released on 1986 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Pt. 1 examines the practical application of parameter estimation methodology to the problem of estimating aircraft stability and control derivatives from flight test data. The primary purpose is to present a comprehensive and unified picture of the entire parameter estimation process and its integration into a flight test program. Pt. 2 covers areas such as flight path reconstruction, nonlinear model identification, optimal input design and flight test instrumentation. This approach is referred to as the Two-Step Method (TSM), also known as Estimation Before Modelling (EBM) in the literature. It will be shown that this approach has significant practical advantages over methods which no attempt is made to decompose the joint parameter-state estimation problem. The two-step method is generally applicable to flight vehicles such as fixed wing aircraft and rotorcraft which are equipped with state of the art inertial reference systems.

Download or read book Structural Dynamic Model Obtained from Flight Use with Piloted Simulation and Handling Qualities Analysis written by Bruce G. Powers and published by . This book was released on 1996 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

Download or read book Modeling XV 15 Tilt rotor Aircraft Dynamics by Frequency and Time domain Identification Techniques written by and published by . This book was released on 1986 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: Models of the open-loop hover dynamics of the XV-15 Tilt-Rotor Aircraft are extracted from flight data using two approaches: frequency-domain and time-domain identification. Both approaches are reviewed and the identification results are presented and compared in detail. The extracted models compare favorably, with the differences associated mostly with the inherent weighting of each technique. Step responses are used to show that the predictive capability of the models from both techniques is excellent. Based on the results of this study, the relative strengths and weaknesses of the frequency and time-domain techniques are summarized, and a proposal for a coordinated parameter identification approach is presented. (Author).

Download or read book Identification of Dynamic Systems written by Richard E. Maine and published by . This book was released on 1986 with total page 167 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pt. 1 examines the practical application of parameter estimation methodology to the problem of estimating aircraft stability and control derivatives from flight test data. The primary purpose is to present a comprehensive and unified picture of the entire parameter estimation process and its integration into a flight test program. Pt. 2 covers areas such as flight path reconstruction, nonlinear model identification, optimal input design and flight test instrumentation. This approach is referred to as the Two-Step Method (TSM), also known as Estimation Before Modelling (EBM) in the literature. It will be shown that this approach has significant practical advantages over methods which no attempt is made to decompose the joint parameter-state estimation problem. The two-step method is generally applicable to flight vehicles such as fixed wing aircraft and rotorcraft which are equipped with state of the art inertial reference systems.

Download or read book Identification Des Syst mes Pour Le D veloppement Int gr Des A ronefs Et Les Essais en Vol written by and published by . This book was released on 1999 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aircraft System Identification written by Eugene Morelli and published by Sunflyte Enterprises. This book was released on 2016 with total page 618 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book The Role of Modeling and Flight Testing in Rotorcraft Parameter Identification written by R. T. N. Chen and published by . This book was released on 1986 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: The importance of recognizing that each lower-order model used for rotorcraft parameter identification has a limited range of applicability is illustrated in some detail. Examples are given to illustrate the use of conditioning the test input signals and the potential of using multi-axis test inputs to enhance the parameter identifiability. The paper discusses the benefits and limitations of using frequency sweeps as flight-test input signals for identification of frequency response for rotorcraft and for the subsequent fitting of parametric transfer-function models. This paper demonstrates the major role played by analytical modeling and the understanding of the physics involved in the rotorcraft flight dynamics, particularly understanding the limit of lower-order models, in achieving successful rotorcraft parameter identification. (Author).

Download or read book Commerce Business Daily written by and published by . This book was released on 1998-10 with total page 1996 pages. Available in PDF, EPUB and Kindle. Book excerpt: