ABSTRACT
Stability of the standard feedback system, Figure 2.11, is determined by checking whether the roots of 1 + G(s) = 0 are in the open left half plane or not, where G(s) = P(s)C(s) is the given open-loop transfer function. Suppose that G(s) has finitely many poles, then it can be written as G = NG /DG , where NG (s) has no poles and DG (s) is a polynomial containing all the poles of G(s). Clearly, 1 + G ( s ) = 0 ⇔ F ( s ) : = D G ( s ) + N G ( s ) D G ( s ) = 0. https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780203750117/ac81ce98-2aa9-4457-91c8-df490c7f3b94/content/eq350.tif"/>
