Some Extensions of Loop Transfer Recovery

In this paper, new conditions for regulator loop transfer recovery (LTR) of minimum phase, non-square, left-invertible, full- or reduced-order observer-based multivariable feedback control systems are derived. It is proved that these conditions are satisfied asymptotically by either the full- or the reduced-order Kalman filters that assume fictitious process noise at the input in the design model. These results eliminate the need for artificially squaring a non-square system and extend the theory to reduced-order observer-based LOG designs. The results are illustrated by a numerical example.