A new interpretation of the LQG/LTR technique using optimal projection equations

It is demonstrated that the LQR/LTR (linear quadratic Gaussian/loop transfer recovery) technique can be viewed as a way to achieve robustness even under the constraint of a reduced-order controller, even though one is not necessarily recovering a desired transfer function asymptotically. The optimal projection equation (OPE) approach gives an expanded view of LQG/LTR technique when the order of the controller is intentionally less than the order of the system design model. Also, the OPE approach allows other forms for Omega , which may give more flexibility as to how the system perturbations are modeled, to be chosen.<>