A reduced-order Unknown Input Observer scheme for a class of nonlinear fractional- order systems

The issue of concepting reduced order continuous-time observers has been subject to several research works. Up to now, only very few papers have treated the specific one-sided Lipschitz class of systems with unknown inputs. Likewise, the literature contains very few works treating reduced order observers for fractional-order systems. Recently, a unifying attempt has been done to construct reduced order observers for one-sided Lipschitz fractional-order systems, but with no unknown inputs in the model. By the present paper, we design a reduced order observer for that same class of systems, taking into consideration the unknown inputs.