A note on spillover and robustness for flexible systems

Many stabilizer designs for infinite-dimensional systems, for example, flexible systems, are based on a finite-dimensional approximation of the original system. It is shown that whether or not this approach leads to a stabilizing controller for the infinite-dimensional system is, in fact, a robustness question: lack of robustness can lead to a spillover effect from the neglected dynamics, which destroys the stability. This phenomenon is illustrated by an example of a damped flexible system