Nonlinear positive observer design for positive dynamical systems

In this paper, the observer design problem is considered for a class of positive dynamical systems. First, we establish a set of sufficient conditions for the design of a general class of positive nonlinear observers for nonlinear positive dynamical systems. Then, the new reduced-order positive observer design techniques are provided for marginally stable and some unstable continuous positive linear systems by thoroughly analyzing the structural properties of sampled systems in terms of reducibility. In particular, a nonlinear reduced-order positive observer is proposed for general reducible positive systems.