Duality between reduced-order observer and sliding mode controller and its application

This paper proposes a new design scheme for a reduced-order state observer. The method is derived by using duality between the design of the reduced-order observer and the design of a switching plane of sliding mode controller. In the method, a reduce-order observer is designed by calculating eigenvectors corresponding to the assigned poles. The method does not require the transformation of state equation into Gopinath form and can assign the poles of the observer directly.