Advanced Modeling and Control for Aeroservoelastic Design

It is well-understood that actuator nonlinearities, such as free-play, can induce limit cycle oscillations (LCO) in otherwise stable closed-loop systems. In flight control systems, free-play specifications are often set conservatively in order to preclude free-play-induced LCO. However, conservative free-play requirements can increase the manufacturing cost of actuators and give rise to a costly program of regular inspections. An analytical method to safely relax free-play limits could significantly reduce actuator manufacturing and lifecycle costs. Importantly, in addition to accurate aeroelastic modeling to predict LCO, proven adaptive control methods exist to mitigate the effects of uncertain actuator nonlinearities, such as free-play. Thus, maximum benefit would be derived from a tool that combines accurate aeroservoelastic modeling and adaptive control to relax free-play manufacturing tolerances, mitigate the adverse closed-loop effects of actuator free-play, and adapt to changes in free-play over time. Barron Associates and its partners propose to develop an Advanced Modeling and Control for Aeroservoelastic Design (AMCAD) Toolbox to provide the Air Force with a rigorous analytical method to establish safe free-play limits for flight control surfaces. AMCAD will feature our recently-developed, computationally-efficient aeroelastic flutter prediction methodology and a proven adaptive control technique for actuator nonlinearity compensation.