Advanced UAV Aerodynamics, Flight Stability and Control

14 Autonomous Gust Alleviation in UAVs

Ya Wang¹ and Daniel J. Inman²

¹ Department of Mechanical Engineering, SUNY, Stony Brook, NY, USA

² Department of Aerospace Engineering, University of Michigan, Ann Arbor, MI, USA

14.1 Introduction

When a gust hits a small, umnanned air vehicle, stability can easily be lost. Various active control schemes have been proposed in the literature to cancel wing vibrations induced by gusts (see for instance Regan and Jutte 2012). The expression ‘gust alleviation’ often refers to load alleviation. Here, however, we are referring specifically to reducing the vibrations induced in a wing by a gust using harvested energy. The whole control scheme is automatic, or autonomous, in a self‐contained way, and does not reduce the power available to the propulsion system. In particular we focus on a system that uses energy absorbed from wing vibrations during normal flight to power a control system that will cancel vibrations induced when the aircraft is subject to a gust. In order to focus on the details of the system design, the air‐flow is modelled in the simplest way, but using the Dryden power spectral density (PSD); see for instance McClean (1990). Other simplifying assumptions include linearity of the structural response and simplified modelling of the composite structure using the rule of mixtures. The basic idea put forth here is that normal “clear sky” induced wing vibrations can be harvested. The resulting energy stored is released later ...