For systems affected by time-varying parameters, we provide a novel constru
ction of controllers that lake on-line measurements of these parameters int
o account to achieve a certain desired performance specification. Since the
controller construction is based on multipliers or scalings that are not,
as typical in many robust control problems, structured but that are full an
d do not need to obey any inertia properties, our results permit to reduce
the conservatism if allowing for arbitrary fast parameter variations to an
arbitrary degree. The paper contains results for parameterized linear matri
x inequalities (full block S-procedure) and dualization as well as eliminat
ion results for quadratic matrix inequalities that are of independent inter
est. (C) 2001 Elsevier Science Ltd. All rights reserved.