Compatibility of Observer and Zero Sensitivity Observer

The compatibility of Luenberger observer designed for a time-invariant linear system is comprehensively discussed and an explicit statement is given for a class of systems to which a given observer is compatible. This class indicates allowable variations of system parameters such that the designed observer functions as an observer even when the parameters are changed. The existence condition and the design method for the observer which has zero sensitivity property to plant parameters are described. Further, as an application, the zero sensitivity of a regulator combined with an observer is shown for a class of parameter variations.