Applied Active Control for a Nonlinear Aeroelastic Structure

Linear and nonlinear aeroelasticresponseisexamined using a uniquetest apparatusthat allowsforexperiments of plunge and pitch motion of a wing with prescribed stiffness characteristics. The addition of a control surface, combined with an active control system, extends the stable e ight region. Unsteady aerodynamics are modeled with an approximation to Theodorsen’ s theory appropriate for the low reduced frequencies associated with the experiment. Incorporated with a full-state feedback control law, an optimal observer is utilized to stabilize the system above the open-loop e utter velocity. Coulomb damping and hardening of the pitch stiffness are included to examine nonlinear control behavior. The nonlinear model is tested using the control laws developed from an extensionoflineartheory.EachmodelissimulatedusingMATLAB ® andcomparedwithexperimentalresultsofthe active control system. Excellent correlation between theory and experiment isachieved. Using an optimal observer and full-state feedback, the linear and nonlinear systems are stabilized at velocities that exceed the open-loop e utter velocity. Limited control is achieved when the system is undergoing limit cycle oscillations.

[1]  Jennifer Heeg,et al.  An analytical and experimental investigation of flutter suppression via piezoelectric actuation , 1992 .

[2]  Yuan-Cheng Fung,et al.  An introduction to the theory of aeroelasticity , 1955 .

[3]  Jennifer,et al.  Analytical and Experimental Investigation of Flutter Suppression by Piezoelectric Actuation , 1993 .

[4]  D. Gangsaas,et al.  Practical gust load alleviation and flutter suppression control laws based on a LQG methodology. [Linear Quadratic Gaussian , 1981 .

[5]  T. Theodorsen.  General Theory of Aerodynamic Instability and the Mechanism of Flutter , 1934 .

[6]  D. B. Debra,et al.  Control law synthesis and sensor design for active flutter suppression. , 1973 .

[7]  P. Chen,et al.  LIMIT-CYCLE-OSCILLATION STUDIES OF A FIGHTER WITH EXTERNAL STORES , 1998 .

[8]  H. Ashley,et al.  Unsteady aerodynamic modeling for arbitrary motions , 1977 .

[9]  E Breitbach.  Effects of Structural Non-Linearities on Aircraft Vibration and Flutter , 1978 .

[10]  Earl H. Dowell,et al.  Flutter and Stall Response of a Helicopter Blade with Structural Nonlinearity , 1992 .

[11]  Mordechay Karpel.  Design for Active Flutter Suppression and Gust Alleviation Using State-Space Aeroelastic Modeling , 1982 .

[12]  Sahjendra N. Singh,et al.  Adaptive Output Feedback Control of a Nonlinear Aeroelastic Structure , 1999 .

[13]  B.H.K. Lee,et al.  Flutter analysis of a two-dimensional airfoil containing structural nonlinearities , 1987 .

[14]  Charrissa Y. Lin,et al.  Strain actuated aeroelastic control , 1993 .

[15]  Kenneth B. Lazarus,et al.  Fundamental mechanisms of aeroelastic control with control surface and strain actuation , 1991 .

[16]  R. Vepa,et al.  On the use of Pade approximants to represent unsteady aerodynamic loads for arbitrarily small motions of wings , 1976 .

[17]  V. Mukhopadhyay,et al.  A direct method for synthesizing low-order optimal feedback control laws with application to flutter suppression , 1980 .

[18]  Robert E. Andrews,et al.  An Investigation of Effects of Certain Types of Structural NonHnearities on Wing and Control Surface Flutter , 1957 .

[19]  Earl H. Dowell,et al.  An Elementary Explanation of the Flutter Mechanism with Active Feedback Controls , 1979 .

[20]  B.H.K. Lee,et al.  Flutter analysis of a two-dimensional airfoil with cubic non-linear restoring force , 1986 .

[21]  Heather Gilliatt,et al.  Active control of an aeroelastic structure , 1997 .

[22]  Kenneth B Lazarus.  Multivariable high-authority control of plate-like active lifting surfaces , 1992 .

[23]  Theodore Theodorsen,et al.  Mechanism of flutter: A theoretical and experimental investigation of the flutter problem , 1938 .

[24]  Andrew J. Kurdila,et al.  Identification and Control of Limit Cycle Oscillations in Aeroelastic Systems , 1999 .