A novel derivation methodology for polynomial-LQ controller design

A simple derivation method for optimization of linear-quadratic (LQ) controllers is presented in the discrete-time polynomial systems framework. A control-law variation, regarded as a potential feedforward from the innovations, is used. Orthogonality is evaluated in the frequency domain by collectively cancelling unstable poles by zeros. The suggested method, summarized as a three-step scheme, is exemplified on a disturbance measurement feedforward and an output feedback problem. It is a simple, more direct alternative to the completing-the-squares approach