The Silver Ratio and its Relation to Controllability

Abstract

This note investigates the controllability of two unstable second-order systems that are coupled through a common input. These dynamics occur for different types of inverted-pendulum systems. Controllability is quantified by the volume of the state-space that can be reached with unit energy, provided that the system starts and ends at the origin. It is shown that controllability is maximized when the ratio between the time constants amounts to the silver ratio.