Positive linear observer design via positive realization

Positive systems are dynamic systems whose trajectories evolve in the nonnegative orthant of the state space if originated from the orthant. The problem of designing a state observer which generates a nonnegative state estimate (called positive observer) is related to the positive realization problem. Constructing the observer via a positive realization of the transfer function of a conventional linear observer, we present an efficient design method for positive linear observers.