Abstract: “In this paper a detailed comparative study has been carried out between two well known methods of reduced order observer construction, namely - Reduced Order Luenberger method (1964, 1971) [1, 2] and Reduced Order Das and Ghosal method (1981) [5]. Through proper examples and illustrations, similarities and dissimilarities between the above mentioned methodsand their advantage & disadvantages are explained in this paper. Brief mathematical preliminaries, a few theorems, lemmas and governing equations are also included in this paper according to the context.”

Keywords: Luenberger Observer, Generalized Matrix Inverse, State Feedback Control, Ackermann’s formula, Full & Reduced order observer, Inverted Pendulum.