Abstract
The Luenberger's observer is frequently used for the estimator of linear time invariant control systems. However, it cannot be applied directly to the plants which have varying parameters.
For this problem, This paper provides an observer whose structure is not affected by the varying parameter of the plant.
The results of this paper give the existence condition and stability condition of such an observer and provide a direct design procedure. The extension of this idea to the design of an unknown input observer is also presented.
