Collaborative Research: Lift regulation via kinematic maneuvering in uncertain gusts

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When a wing passes through a strong gust of wind, large amounts of lift are generated very quickly. The resulting lift transient, and the speed at which it builds, presents a challenge to maintaining vehicle control and can result in structural deformation or failure. It is therefore of interest to equip wings with ways to mitigate strong gust responses, i.e., to regulate lift. The long-term goal of this project is to assess the sensitivity of lift production to uncertainties in the gust flow, and to create new control strategies for mitigation of lift transients during detrimental unforeseen gust encounters. Results of this work will apply to a broad range of applications including wind and water turbines operating in tides, waves, and wakes; and air and water vehicles of all scales, from small aerial vehicles operating in urban environments to manned vehicles operating in complex terrain, air wakes, and extreme weather. The project will also encompass educational and outreach activities, including elementary and middle school visits and a research and mentoring program for undergraduate transfer students.The goal of this project is to apply tools from fluid dynamics, reduced-order modeling, and optimal and robust control theory to elucidate and model the underlying flow physics of an unsteady and uncertain large-amplitude transverse gust encounter, and to apply this knowledge to design control laws for regulation of lift production through kinematic actuation during and after this event. The technical approach is to (1) synthesize a physics-based low-order model that includes leading- and trailing-edge vortex dynamics based on high-resolution unsteady force, flow field, and surface pressure measurements on a rigid wing in a large-amplitude transverse gust encounter; (2) construct an optimal robust control framework for lift regulation in the gust that properly accounts for uncertainties in the gust flow (e.g., width and amplitude) and the wing's response thereto; and (3) implement the proposed closed-loop control framework in real-time gust encounter experiments in the laboratory. Research activities will explore methods of combining analytical and physics-based aerodynamic models with data-driven techniques for more robust and extensible models of wings passing through unsteady and uncertain large disturbances. Contributions to the scientific community include (1) a flow model designed for large-amplitude gust encounters with a high degree of uncertainty in the gust flow, and (2) integration of this model into a robust real-time feedback control loop for kinematic maneuvering in a wing-gust encounter without a priori knowledge of the gust parameters.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.