Use of power and energy concepts in the analysis of multivariable feedback controllers

The general linear-feedback multivariable-regulator problem is considered in terms of the injection of power into the controlled system by the controller. The concepts of power, energy, power decomposition, active power and reactive power are studied in this context and shown to give a physical insight into the techniques of modal control and spin-space mapping. An analogy is established between the energy exchanges of a system and its controller, and the energy-interchange effects in quantum mechanics.