The governing equation for the system (Plant) in state-space representation may be expressed as

(26.1)

The governing equation for the Observer based on Fig. 26.1 is

	(26.2)

where the superscript 'Λ' denotes estimation.

Subtracting Eqns. (26.1) to (26.2) and defining the error in estimation of state vector as

one may get the equation of motion corresponding to error dynamics as

	(26.3)

The characteristic equation related to the error dynamics (Eqn. (26.3) is

(26.4)