  In this paper, we propose a model reduction technique for linear parameter
varying (LPV) systems based on available tools for fixed-structure controller
synthesis. We start by transforming a model reduction problem into an
equivalent controller synthesis problem by defining an appropriate generalized
plant. The controller synthesis problem is then solved by using gradient-based
tools available in the literature. Owing to the flexibility of the
gradient-based synthesis tools, we are able to impose a desired structure on
the obtained reduced model. Additionally, we obtain a bound on the
approximation error as a direct output of the optimization problem. The
proposed methods are applied on a benchmark mechanical system of interconnected
masses, springs and dampers. To evaluate the effect of the proposed
model-reduction approach on controller design, LPV controllers designed using
the reduced models (with and without an imposed structure) are compared in
closed-loop with the original model.
