Comparison of μ- and H2-Synthesis Controllers on an Experimental Typical Section

Abstract

An experimental comparison of H2 - and μ-synthesized flutter suppression control systems was performed. A simple parametric uncertainty can be used to track changes in system dynamics as a function of dynamic pressure. The control system was implemented experimentally on a NACA 0012 test model of a typical section mounted in a low-speed wind tunnel. The pitching angle, flap angle, and plunge deflection of the airfoil were measured with sensors and fed back through the control compensator to generate a single control signal commanding the trailing-edge flap of the airfoil. The model of the aeroelastic system, including the dynamics of the sensors and actuators in the bandwidth of interest, was obtained using system identification techniques. For comparison purposes, an H2 control system with standard linear quadratic Gaussian weightings also was designed and implemented. When compared to the H2 control system, the μ-synthesis controller provided better disturbance rejection in the bandwidth of the unsteady aeroelastic dynamics. In addition, the μ controller required less control energy than the H2 control system. The final advantage of μ-synthesis is the ability to design an aggressive μ control system that is stabilizing across the range of operating dynamic pressures.