Design and Testing of Gust Load Alleviation Control Laws for the IAWTM Wind Tunnel Test

This paper summarizes the design and testing of gust load alleviation (GLA) control laws developed for the Integrated Adaptive Wing Technology Maturation (IAWTM) wind tunnel test campaign at NASA's Langley Research Center Transonic Dynamics Tunnel (TDT). The IAWTM program is a joint NASA and Boeing effort to demonstrate and validate control and sensing technologies necessary to enable higher aspect ratio flexible transport aircraft. Two of the primary drivers of wing structural sizing in a flexible, high aspect ratio wing are the maneuver and gust loads experienced by the aircraft in the flight envelope. Gust load alleviation control laws aim to reduce the gust loads experienced by the aircraft in flight in order to minimize the required wing structure, reduce fatigue associated with larger gust loads, and improve passenger ride quality. As part of the IAWTM program, multiple GLA control laws were developed by NASA and Boeing and tested in the TDT. One of the designs utilizes gust measurement devices positioned upstream of the test article in the TDT to act as a surrogate LIDAR for a forward-looking feedforward controller. The second control law is a multi-objective linear quadratic Gaussian design with the objective of minimizing wing root strain, which utilizes the onboard accelerometer and strain gage sensors for estimation and feedback. NASA also developed a third Hamiltonian-based control law. The designs for the controllers are presented and the wind tunnel results for the June 2025 tests are summarized All three controllers demonstrates a reduction in inboard strain at different gust frequencies.