Comments on "Robust, fragile, or optimal?" [with reply]

The issue of fragile controllers produced by using popular robust and optimal control synthesis methods was raised by Keel-Bhattacharyya in the above mentioned paper (ibid. vol.42 (1997)). The commenter points out that the controller fragility problem described in the paper is: 1) well known in the literature; 2) due to the poor choice of examples; 3) can easily be fixed by changing the optimization criteria; and 4) can be fixed by changing the implementation. In reply, Keel-Bhattacharyya disagree with him on all counts and explain their argument.

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