Is Controller Fragility a problem inherent to Robust Control?
Department of Mechanical Engineering
We will criticize most of the conclusions reached
in a recent IEEE Transactions on Automatic Control publication,
``Robust, Fragile or Optimal,'' (August 1997, Keel and
While we do not dispute the numerical correctness of the paper's
results, we believe that the interpretations reached by the authors
misleading. A thorough analysis of each example, modeling
controllers as dynamic systems with imperfect components,
bolsters our viewpoint. We will also comment on a
published letter to TAC and the 1998 ACC session on the topic.
Our perspective is joint work with David Faris, Tom Pare, Jonathan
and Khalid Al-Ali.