A chapter titled “Modified Reference Model MRAC (M-MRAC): An Application to a Generic Transport Aircraft,” by Vahram Stepanyan and Kalmanje Krishnakumar, was published in the book Advances in Intelligent and Autonomous Aerospace Systems. The book is part of the American Institute of Aeronautics and Astronautics (AIAA) series “Progress in Astronautics and Aeronautics.”
This chapter addresses aircraft resiliency via an inner-loop adaptive control that incorporates a new modification for handling larger uncertainties that typically require large adaptive gains when using conventional Model Reference Adaptive Control (MRAC). Large uncertainties, such as aircraft damage, actuator and sensor failures, and environmental factors, are common causes of large transport aircraft loss-of-control incidents and accidents. The proposed approach is based on feeding back the tracking error signal to modify the reference model of the control system of a conventional MRAC design. When doing so, the following benefits are observed: a stable adaptation that allows a large adaptive gain to be used for better tracking performance with improved stability robustness; and guaranteed tracking of a given command and the ideal control signal (one that would be designed if the system were known), not only asymptotically, but also in transient. The resulting control signal is free of oscillations, which are unavoidable for large adaptation rates in MRAC. The provided design guideline makes it possible to track a reference command of any magnitude from any initial position without controller re-tuning.
NASA PROGRAM FUNDING: Vehicle Safety Systems Technologies (VSST) project, Aviation Safety Program, Aeronautics Research Mission Directorate (ARMD)
TEAM: Vahram Stepanyan (MCT) and Kalmanje Krishnakumar (NASA)
Contact: Vahram Stepanyan