Global estimation of nonlinear systems with unknown-input coefficients

This paper deals with simultaneous state and input-parameter estimation of a class of bounded-state nonlinear systems. By state augmentation, the unknown-input coefficient is seen as an extension of the system states and consequently, an input-gain observer can be conceived to steer the observation error to the origin for some bounded and non-null control input. The proposed design remains valid for nonlinear-input systems with linear parametrization.