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Proceedings ArticleDOI

Experimental validation of generalized predictive control for active flutter suppression

15 Sep 1996-pp 125-129
TL;DR: In this paper, a generalized predictive controller is proposed for flutter control of a subsonic airfoil, which is based on the minimization of a suitable cost function over a finite prediction horizon.
Abstract: This paper presents a status report on the experimental results of the transonic wind-tunnel test conducted to demonstrate the use of generalized predictive control for flutter control of a subsonic airfoil. The generalized predictive control algorithm is based on the minimization of a suitable cost function over a finite prediction horizon. The cost function minimizes the sum of the mean square output of the plant predictions using a suitable plant model, weighted square of control increments, and the term which incorporates the input constraints. The characteristics of the subsonic airfoil are such that its dynamics are invariant to low input frequencies. This results in a control surface that drifts within the specified input constraints. An augmentation to the cost function that penalizes this low frequency drift is derived and demonstrated. The initial validation of the controller uses a linear plant predictor model for the computation of the control inputs. The generalized predictive controller based on this model could successfully suppress the flutter for all testable mach numbers and dynamic pressures in the transonic region. The wind-tunnel test results confirmed that the generalized predictive controller is robust to modeling errors. The simulation results that were used to determine the nominal ranges for control parameters before wind-tunnel testing are also included. The wind-tunnel test results were in good agreement with the results of the simulation.

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Citations
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01 Jan 2006
TL;DR: In this paper, the authors used linear matrix inequalities (LMIs) techniques to design an active state-feedback control to suppress flutter, which is a potentially destructive instability resulting from an interaction between aerodynamic, inertial, and elastic forces.
Abstract: Flutter is an in-flight vibration of flexible structures caused by energy in the airstream absorbed by the lifting surface. This aeroelastic phenomenon is a problem of considerable interest in the aeronautic industry, because flutter is a potentially destructive instability resulting from an interaction between aerodynamic, inertial, and elastic forces. To overcome this effect, it is possible to use passive or active methodologies, but passive control adds mass to the structure and it is, therefore, undesirable. Thus, in this paper, the goal is to use linear matrix inequalities (LMIs) techniques to design an active state-feedback control to suppress flutter. Due to unmeasurable aerodynamic-lag states, one needs to use a dynamic observer. So, LMIs also were applied to design a state-estimator. The simulated model consists of a classical flat plate in a two-dimensional flow. Two regulators were designed, the first one is a non-robust design for parametric variation and the second one is a robust control design, both designed by using LMIs. The parametric uncertainties are modeled through polytopic uncertainties. The paper concludes with numerical simulations for each controller. The open-loop and closed-loop responses are also compared and the results show the flutter suppression. The perfomance for both controllers are compared and discussed. Keywords : Flutter, active control, LMI, polytopic uncertainties, robustness

13 citations

Journal ArticleDOI
TL;DR: In this article, the authors proposed a method to solve the problem of artificial intelligence in the context of the State University of Campinas (UNICAMP Cidade Universitaria, Rua Mendeleiev s/n, 13083-970 Campinas, SP
Abstract: Department of Mechanical Design State University of Campinas - UNICAMP Cidade Universitaria, Rua Mendeleiev s/n, 13083-970 Campinas, SP

12 citations


Cites background from "Experimental validation of generali..."

  • ...Haley and Soloway (1996) have made an experimental investigation in a transonic wind-tunnel to demonstrate the use of the generalized predictive control for flutter suppression of a subonic airfoil....

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  • ...The idea is old and it was first tested in 1973 on a B-52-E aircraft that achieved flight velocity above the specified limit, besides some problems with model accuracy and robustness, (Garrick, 1976)....

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Journal ArticleDOI
TL;DR: In this article, a subsonic passenger aircraft in its cruise speed was analyzed using optimization tools CFD and FEA tools, and the results were exposed computationally including both fluid and structural interaction problem, which can able to predict accurately the nature of an aircraft during its flutter.

10 citations

Journal ArticleDOI
TL;DR: Aeroelasticity is the study of the mutual interaction that takes place among the inertial, elastic and aerodynamic forces acting on the structural members exposed to an airstream and the influence of this study on the design as mentioned in this paper.

4 citations

References
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Proceedings ArticleDOI
29 Jul 1996
TL;DR: In this article, the authors describe the formulation of a model of the dynamic behavior of the Benchmark Active Controls Technology (BACT) wind-tunnel model for application to design and analysis of flutter suppression controllers.
Abstract: This paper describes the formulation of a model of the dynamic behavior of the Benchmark Active Controls Technology (BACT) wind-tunnel model for application to design and analysis of flutter suppression controllers. The model is formed by combining the equations of motion for the BACT wind-tunnel model with actuator models and a model of wind-tunnel turbulence. The primary focus of this paper is the development of the equations of motion from first principles using Lagrange''s equations and the principle of virtual work. A numerical form of the model is generated using values for parameters obtained from both experiment and analysis. A unique aspect of the BACT wind-tunnel model is that it has upper- and lower-surface spoilers for active control. Comparisons with experimental frequency responses and other data show excellent agreement and suggest that simple coefficient-based aerodynamics are sufficient to accurately characterize the aeroelastic response of the BACT wind-tunnel model. The equations of motion developed herein have been used to assist the design and analysis of a number of flutter suppression controllers that have been successfully implemented.

62 citations


"Experimental validation of generali..." refers methods in this paper

  • ...The model of the BACT plant was a reduced order discrete model based on the model obtained in [ 8 ]3 . The sampling frequency for the discretization was 200 Hertz....

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  • ...simulated using a linear model that was previously developed from the knowledge of the plant and system identification techniques using preexisting wind-tunnel data [ 8 ]....

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01 Jul 1992
TL;DR: The Benchmark Models Program at NASA LaRC as discussed by the authors is a multi-year activity that will involve testing of several different models to investigate various aeroelastic phenomena, such as a rigid semispan wing having a rectangular planform and a NACA 0012 airfoil shape.
Abstract: The Structural Dynamics Division at NASA LaRC has started a wind tunnel activity referred to as the Benchmark Models Program. The primary objective of the program is to acquire measured dynamic instability and corresponding pressure data that will be useful for developing and evaluating aeroelastic type CFD codes currently in use or under development. The program is a multi-year activity that will involve testing of several different models to investigate various aeroelastic phenomena. The first model consisted of a rigid semispan wing having a rectangular planform and a NACA 0012 airfoil shape which was mounted on a flexible two degree-of-freedom mount system. Two wind-tunnel tests were conducted with the first model. Several dynamic instability boundaries were investigated such as a conventional flutter boundary, a transonic plunge instability region near Mach = 0.90, and stall flutter. In addition, wing surface unsteady pressure data were acquired along two model chords located at the 60 to 95-percent span stations during these instabilities. At this time, only the pressure data for the conventional flutter boundary is presented. The conventional flutter boundary and the wing surface unsteady pressure measurements obtained at the conventional flutter boundary test conditions in pressure coefficient form are presented. Wing surface steady pressure measurements obtained with the model mount system rigidized are also presented. These steady pressure data were acquired at essentially the same dynamic pressure at which conventional flutter had been encountered with the mount system flexible.

21 citations