Output Feedback Control of the Nonlinear Aeroelastic Response of a Slender Wing

Abstract

This paper presents the design of optimal constant gain output feedback based controllers for a nonlinear aeroelastic system. Controllers are designed for flutter suppression as well as gust-load alleviation. This controller architecture is one of the simplest, using direct feedback of the sensor outputs, but its performance is highly dependent on sensor selection and placement. Also, optimal design of such controllers require an accurate knowledge of the expected disturbance mode and gust spectrum. This paper presents results pertaining to the performance of SOF controllers for aeroelastic control (linear and nonlinear) and compares it to that of LQR and LQG controllers. Controllers are designed for various sensor placement. The gain and phase margins of the various controllers are also presented to understand the robustness characteristics. For optimal sensor placement and with knowledge of the disturbance, the constant gain output feedback controller performance and robustness was found to be equivalent to that of linear quadratic regulator and linear quadratic Gaussian controllers for the example considered. These controllers were also shown to be very easy to alter and combine with other controllers/filters for better overall system response.