Robustness of adaptive control systems to unmodeled dynamics : a describing function viewpoint

Thesis: S.B., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.Cataloged from PDF version of thesis.Includes bibliographical references (pages 43-44).Recently, it was shown that a standard model reference adaptive controller modified with a suitably tuned projection algorithm ensures robustness (global boundedness) of the overall adaptive system to a class of unmodeled dynamics with minimal restrictions. However, extensive first-principle based arguments and/or analysis of the parameter trajectory is employed. An alternative to such analysis, albeit approximate, is to use the well-known Describing Function (DF) method. In doing so, the analysis of the robust adaptive control problem becomes tractable and resembles that of familiar and classical linear stability analysis.by Chandan Sharma Subedi.S.B