  We present a new approach to parametric robust controller design, where we
compute controllers of arbitrary order and structure which minimize the
worst-case $H_\infty$ norm over a pre-specified set of uncertain parameters. At
the core of our method is a nonsmooth minimization method tailored to functions
which are semi-infinite minima of smooth functions. A rich test bench and a
more detailed example illustrate the potential of the technique, which can deal
with complex problems involving multiple possibly repeated uncertain
parameters.
