Lift Regulation During Transverse Gust Encounters Using a Modified Goman-Khrabrov Model

This paper presents a framework for the estimated state regulation of the lift force for a maneuvering wing during a transverse gust encounter. An expression for the effective angle of attack of the wing is derived and used to construct a modified Goman-Khrabrov (GK) model for wing-gust encounters. Experiments were carried out in the University of Maryland water towing facility to identify parameters in the modified GK model and to evaluate its ability to represent gust encounters of varying gust strengths. Using this gust-encounter model, an observer-based feedback controller for pitch actuation is constructed to regulate the coefficient of lift of a wing during a transverse gust encounter. Closed-loop control simulations provided pitching kinematics that mitigated the transient force response. Gust encounter experiments were performed using the control signal from simulation as an open-loop control signal during an encounter with a known gust. The lift force time histories of the gust encounter experiments with control show effective mitigation of the peak lift force. The wing experienced transient forces that merit further investigation, including an initial transient peak and a later undershoot that may be due to uncertainty in the start of the gust region.