DESIGN AND EXAMINATION OF H-INFINITY ROBUST CONTROLLER FOR GROUND EFFECT PROBLEM

An aeroelastic problem in the ground effect is treated. The H(i)nfinity control theory based on the loop-shaping design procedure is applied to designing controllers for flutter suppression and attenuation of the aerodynamic disturbance caused by the ground irregulation. A two-dimensional Bat-plate airfoil with three degrees of freedom, plunging, pitching, and control surface deflection is treated. The aeroelastic characteristics vary according to the altitude at which the airfoil is flying. Stability analysis and controller design are performed with the models with aerodynamic data obtained by the doubler-lattice method aerodynamic calculations and Pade approximation with two lag terms. Examination of robustness of the designed controllers are performed with numerical experiments using the finite difference method.