A Multi-Channel H_infinity Preview Control Approach to Load Alleviation Function Design

Abstract

Gust load alleviation functions are mainly designed for two objectives: first, alleviating the structural loads resulting from turbulence or gust encounter, and hence reducing the structural fatigue and/or reducing the structural weight; and second, enhancing the ride qualities, and hence the passengers' comfort. Whilst load alleviation functions can improve both aspects, the designer will still need to make design tradeoffs between these two objectives and between various types and locations of the structural loads. The possible emergence of affordable and reliable remote wind sensor techniques (e.g. Doppler LIDAR) in the future also leads to consider new types of load alleviation functions as these sensors would permit to anticipate the near future gusts and other types of turbulence. In this paper, we propose a preview control design methodology for the design of a load alleviation function with such anticipation capabilities based on recent advancements on discrete-time reduced-order multi-channel H_infinity techniques. The methodology is illustrated on the DLR Discus-2c flexible sailplane model.