Reply to 'Comments on the robust stability analysis of adaptive controllers using normalizations'

The author addresses a statement in the above-titled paper by P.P. Khargonekar and R. Ortega (see ibid., vol. 34, no. 4, p. 478, April (1989)) that the proofs in four earlier papers, including two of which he is a coauthor, failed to establish that the proposed adaptive controllers provide a nonvanishing robustness margin for the considered class of unmodeled dynamics. He shows that the results in those papers are correct and that the above statement and its implications are misleading. He also rebuts an incorrect statement that mu * is inversely proportional to the initial condition mod eta (0) mod of the unmodeled dynamics, leading the reader to the conclusion that the results of the four papers cannot be global with respect to mod eta (0) mod .