Output Feedback Variable Structure Adaptive Control of an Aeroelastic Systems

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The question of control of a class of aeroelastic systems with structural nonlinearities based on the variable structure model reference adaptive control theory is treated. It is assumed that the system parameters are unknown and unmodeled nonlinear functions are present in the model. Control laws for the trajectory control of pitch angle and plunge displacement are derived. For the synthesis of controllers, only measured output variable (pitch angle or plunge displacement) is used for feedback. The feedback loop includes two relays, whose outputs are functions of certain auxiliary error signals. Modulation functions of the relays are generated on-line using bounds on uncertain functions and signals derived from the input and output of the system. Digital simulation results are presented that show that in the closed-loop system with only output feedback, pitch angle, and plunge displacement are smoothly regulated to zero in spite of the uncertainty and unmodeled functions in the system.


Adaptive control systems; Aeroelasticity; Airplanes—Wings; Nonlinear control theory; Nonlinear systems; Stability of airplanes


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