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Journal ArticleDOI

Multiple input design for real-time parameter estimation in the frequency domain

01 Sep 2003-IFAC Proceedings Volumes (Elsevier)-Vol. 36, Iss: 16, pp 639-644
TL;DR: In this article, a method for designing multiple inputs for real-time dynamic system identification in the frequency domain was developed and demonstrated The designed inputs are mutually orthogonal in both the time and frequency domains with reduced peak factors to provide good information content for relatively small amplitude excursions.
About: This article is published in IFAC Proceedings Volumes.The article was published on 2003-09-01 and is currently open access. It has received 104 citations till now. The article focuses on the topics: Frequency domain & System identification.

Summary (1 min read)

1. INTRODUCTION

  • The next section describes the multiple input design procedure.
  • Following this, real-time parameter estimation results from applying the designed inputs to the F-15 ACTIVE simulation are presented and discussed.

3. RESULTS

  • For the linearized 1ateraYdirectional dynamics of the F-15 ACTIVE aircraft, the state vector x and input vector u in@.
  • The values of the parameters in the model that were used to generate the simulated data are given in column 2 of Table 1 .

Fig. 2. F-15 ACTIVE Aircraft

  • The multiple input design for the F-15 ACTIVE aircraft laterddirectional dynamics includes four control effectors: aileron, rudder, differential canard, and differential stabilator.
  • These inputs were designed using a flat power spectrum with T' 15 sec.
  • All of the designed inputs achieved an extremely low relative peak factor close to 1.
  • Real-time parameter estimation in the frequency domain (Morelli, 2000) was used to estimate the parameters.
  • For output signal-to-noise ratio equal to 10, the input amplitudes were 0.24 deg, and the mean parameter estimate error was 2.7 percent.

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Citations
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Journal ArticleDOI
TL;DR: The past, present, and future of system identification applied to aircraft at NASA Langley Research Center (LaRC) in Hampton, Virginia are discussed in this article, including some perspective on the role these developments played in the practice of identifying aircraft.
Abstract: The past, present, and future of system identification applied to aircraft at NASA Langley Research Center (LaRC) in Hampton, Virginia, are discussed. Significant research advances generated at NASA LaRC in the past are summarized, including some perspective on the role these developments played in the practice of system identification applied to aircraft. Selected recent research efforts are described, to give an idea of the type of activities currently being pursued at NASA LaRC. These efforts include real-time parameter estimation, identifying flying qualities models, advanced experiment design and modeling techniques for static wind-tunnel database development, and indicial function identification for unsteady aerodynamic modeling. Projected future developments in the area are outlined

127 citations

Journal ArticleDOI
TL;DR: In this article, a maneuver design method that is particularly well-suited for determining the stability and control characteristics of hypersonic vehicles is described in detail, and analytical properties of the maneuver design are explained.
Abstract: A maneuver design method that is particularly well-suited for determining the stability and control characteristics of hypersonic vehicles is described in detail. Analytical properties of the maneuver design are explained. The importance of these analytical properties for maximizing information content in flight data is discussed, along with practical implementation issues. Results from flight tests of the X-43A hypersonic research vehicle (also called Hyper-X) are used to demonstrate the excellent modeling results obtained using this maneuver design approach. A detailed design procedure for generating the maneuvers is given to allow application to other flight test programs.

122 citations

Journal ArticleDOI
TL;DR: In this paper, flight test maneuvers for efficient aerodynamic modeling were developed and demonstrated in flight, where orthogonal optimized multi-sine inputs were applied to aircraft control surfaces to excite aircraft dynamic response in all six degrees of freedom simultaneously while keeping the aircraft close to chosen reference flight conditions.
Abstract: Novel flight test maneuvers for efficient aerodynamic modeling were developed and demonstrated in flight. Orthogonal optimized multi-sine inputs were applied to aircraft control surfaces to excite aircraft dynamic response in all six degrees of freedom simultaneously while keeping the aircraft close to chosen reference flight conditions. Each maneuver was designed for a specific modeling task that cannot be adequately or efficiently accomplished using conventional flight test maneuvers. All of the new maneuvers were first described and explained, then demonstrated on a subscale jet transport aircraft in flight. Real-time and post-flight modeling results obtained using equation-error parameter estimation in the frequency domain were used to show the effectiveness and efficiency of the new maneuvers, as well as the quality of the aerodynamic models that can be identified from the resultant flight data.

91 citations

Journal ArticleDOI
TL;DR: Practical aspects of identifying dynamic models for aircraft in real time were studied and Estimated parameter standard errors, prediction cases, and comparisons with results from postflight analysis using the output-error method in the time domain were used to demonstrate the accuracy of the identified real-time models.
Abstract: Practical aspects of identifying dynamic models for aircraft in real time were studied. Topics include formulation of an equation-error method in the frequency domain to estimate non-dimensional stability and control derivatives in real time, data information content for accurate modeling results, and data information management techniques such as data forgetting, incorporating prior information, and optimized excitation. Real-time dynamic modeling was applied to simulation data and flight test data from a modified F-15B fighter aircraft, and to operational flight data from a subscale jet transport aircraft. Estimated parameter standard errors, prediction cases, and comparisons with results from a batch output-error method in the time domain were used to demonstrate the accuracy of the identified real-time models.

87 citations

Proceedings ArticleDOI
09 Jan 2012
TL;DR: In this article, a method for identifying global aerodynamic models from flight data in an efficient manner is explained and demonstrated, and a novel experiment design technique is used to obtain dynamic flight data over a range of flight conditions with a single flight maneuver.
Abstract: A method for identifying global aerodynamic models from flight data in an efficient manner is explained and demonstrated. A novel experiment design technique was used to obtain dynamic flight data over a range of flight conditions with a single flight maneuver. Multivariate polynomials and polynomial splines were used with orthogonalization techniques and statistical modeling metrics to synthesize global nonlinear aerodynamic models directly and completely from flight data alone. Simulation data and flight data from a subscale twin-engine jet transport aircraft were used to demonstrate the techniques. Results showed that global multivariate nonlinear aerodynamic dependencies could be accurately identified using flight data from a single maneuver. Flight-derived global aerodynamic model structures, model parameter estimates, and associated uncertainties were provided for all six nondimensional force and moment coefficients for the test aircraft. These models were combined with a propulsion model identified from engine ground test data to produce a high-fidelity nonlinear flight simulation very efficiently. Prediction testing using a multi-axis maneuver showed that the identified global model accurately predicted aircraft responses.

86 citations

References
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Book
05 Feb 1992
TL;DR: Equations of Motion Building the Aircraft Model Basic Analytical and Computational Tools Aircraft Dynamics and Classical Design Techniques Modern Design Techniques Robustness and Multivariable Frequency-Domain Techniques Digital Control Appendices Index.
Abstract: Equations of Motion Building the Aircraft Model Basic Analytical and Computational Tools Aircraft Dynamics and Classical Design Techniques Modern Design Techniques Robustness and Multivariable Frequency-Domain Techniques Digital Control Appendices Index.

2,837 citations

Journal ArticleDOI
01 Apr 1976

1,524 citations


Additional excerpts

  • ...~x x t e dt j t T ω ω 1 6 1 6 Ÿ I0 (5)...

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Journal ArticleDOI
TL;DR: In this correspondence, a formula for the phase angles is derived that yields generally low peak factors, often comparable to that of a sinusoidal signal of equal power.
Abstract: This correspondence considers the problem of how to adjust the phase angles of a periodic signal with a given power spectrum to minimize its peak-to-peak amplitude. This "peak-factor problem" arises in radar, sonar, and numerous other applications. However, in spite of the wide-spread interest it has evoked, the peak-factor problem has so far defied solution except in cases where the number of spectral components is small enough to permit an effectively exhaustive search of all phase angle combinations. In this correspondence, a formula for the phase angles is derived that yields generally low peak factors, often comparable to that of a sinusoidal signal of equal power. A formula is also derived for the case in which the phase angles are restricted to 0 and \pi . The latter formula is applicable to the problem of constructing binary sequences of arbitrary length with Iow autocorrelation coefficients for nonzero shifts.

724 citations


"Multiple input design for real-time..." refers background in this paper

  • ...The task is then to identify accurate linear model parameter estimates from measured data in real time, so that the adaptive control logic can make the necessary 2 American Institute of Aeronautics and Astronautics changes to the control law to achieve stability and performance goals....

    [...]

01 Dec 1979
TL;DR: In this paper, a real-time piloted simulation was conducted to evaluate the high-angle-of-attack characteristics of a fighter configuration based on wind-tunnel testing of the F-16 with particular emphasis on the effects of various levels of relaxed longitudinal static stability.
Abstract: A real-time piloted simulation was conducted to evaluate the high-angle-of-attack characteristics of a fighter configuration based on wind-tunnel testing of the F-16, with particular emphasis on the effects of various levels of relaxed longitudinal static stability. The aerodynamic data used in the simulation was conducted on the Langley differential maneuvering simulator, and the evaluation involved representative low-speed combat maneuvering. Results of the investigation show that the airplane with the basic control system was resistant to the classical yaw departure; however, it was susceptible to pitch departures induced by inertia coupling during rapid, large-amplitude rolls at low airspeed. The airplane also exhibited a deep-stall trim which could be flown into and from which it was difficult to recover. Control-system modifications were developed which greatly decreased the airplane susceptibility to the inertia-coupling departure and which provided a reliable means for recovering from the deep stall.

396 citations


Additional excerpts

  • ...T T m m 1 1 2 2 1 6 1 6 1 6 1 6 1 6 1 6 M M (14)...

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Journal ArticleDOI
TL;DR: In this paper, a method for real-time estimation of parameters in a linear dynamic state space model was developed and studied for aircraft dynamic model parameter estimation from measured data in flight for indirect adaptive or reconfigurable control.
Abstract: A method for real-time estimation of parameters in a linear dynamic state space model was developed and studied. The application is aircraft dynamic model parameter estimation from measured data in flight for indirect adaptive or reconfigurable control. Equation error in the frequency domain was used with a recursive Fourier transform for the real-time data analysis. Linear and nonlinear simulation examples and flight test data from the F-18 High Alpha Research Vehicle HARV) were used to demonstrate that the technique produces accurate model parameter estimates with appropriate error bounds. Parameter estimates converged in less than 1 cycle of the dominant dynamic mode natural frequencies, using control surface inputs measured in flight during ordinary piloted maneuvers. The real-time parameter estimation method has low computational requirements, and could be implemented aboard an aircraft in real time.

220 citations


"Multiple input design for real-time..." refers methods in this paper

  • ...Real-time parameter estimation in the frequency domain (Morelli, 2000) was used to estimate the dynamic model parameters....

    [...]

  • ...Recent work has indicated that real-time parameter estimation for a i r d dynamic models can be done effectively using a recursive c h i p Z transform for a selected frequency band, then employing equation-error parameter estimation in the frequency domain (Morelli, 2000)....

    [...]