Wind Tunnel Assessment of a Robust Gust Load Alleviation Controller Designed Using µ-Synthesis

Abstract

Gust and turbulence loads are a sizing case in the structural design of a transport aircraft, particularly for those with high aspect ratio wings. Active control technologies can help reduce these loads, leading to a lighter aircraft design, which in turn reduces fuel consumption and emissions. Robust control is a well-suited method to develop controllers for the multi-variable aeroservoelastic system, with µ-synthesis providing explicit treatment of system uncertainties to guarantee robust performance and stability. However, applying µ-synthesis presents the challenge of translating the desired control objectives into the synthesis framework that includes a generalized plant and weighting functions. This paper addresses this challenge in the context of designing a gust load alleviation controller, which is intended for experimental testing in a wind tunnel. The goal is to demonstrate the practical applicability of the µ-synthesis method and to develop a guideline for controller design. Competing control objectives, such as performance, control effort, and robustness, will be explicitly addressed and balanced within the design process. The benefits of µ-synthesis for controller design in multi-variable systems are explored by comparing three different controllers, each utilizing different subsets of sensors and actuators. The developed controllers are experimentally validated by wind tunnel testing.