O.  Omorogiuwa, E.C.  Obinabo, 
    On the Design of Optimal Output Regulators for Linear Time-Invariant Multivariable Systems,
    International Journal of System Signal Control and Engineering Application,
    Volume 2,Issue 3-4,
    2009,
    Pages 45-50,
    ISSN 1997-5422,
    ijssceapp.2009.45.50,
    (https://makhillpublications.co/view-article.php?doi=ijssceapp.2009.45.50)
    Abstract: This study presents the design of an optimal output regulator for application to a linear time-invariant multivariable system based on the use of a vector of inputs and outputs and a matrix of operations characterizing the input-output relations, assuming the system is both controllable and observable under arbitrary state feedback. The stability property of the solution which is desirable from the view point of feedback control design was clarified.
    Keywords: optimal output regulators;interconnected electric power generating plants;multivariable systems;Stability functions;decouplable linear systems;clarified