This paper addresses the design of reduced-order interval-observers for dynamic systems with time-invariant uncertainty. Because of the limitations of using the set-based approach to preserve the time dependency of parameter uncertainty and the wrapping effect to deal with interval-observers, the trajectory-based interval-observer approach is used with an appropriate observer gain. But, there c...

For joint estimation of state variables and unknown parameters, adaptive observers usually assume some persistent excitation (PE) condition. In practice, the PE condition may not be satisfied, because underlying recursive problem is ill-posed. To remedy lack condition, inspired by ridge regression, this paper proposes a regularized observer with enhanced parameter adaptation gain. Like in typic...

The paper proposes a method for observer design for a class of nonlinear systems. We decompose the system using a weaker concept than the relative degree. We provide sufficient conditions for global asymptotic stability of the error dynamics. The observer design is carried out by means of a change of coordinates combined with a high gain technique. In particular, our approach results in an obse...

A full-order observer accomplishes its purpose by calculating the “residual,” which is the difference between the measured output and the corresponding quantity generated by a model of S synthesized in the observer. The residual, multiplied by a “gain” is used as an input to a model of S . If the gain is chosen appropriately, the observer Ŝ will be an asymptotically stable dynamic system and th...

In this paper, the properties of a high gain observer-based disturbance estimation are analysed, and a time delay calculation approach is proposed for improving the identification of model parameter variation. The focus of this paper is the time delay between the actual disturbance and its estimate in a high gain disturbance estimation observer. It is proved, in this paper, the delay depends on...

A high gain observer is proposed for a class of multi-output nonlinear systems with unknown inputs in order to simultaneously estimate the whole state as well as the unknown inputs. The gain of this observer does not require the resolution of any dynamical system and is explicitly given. Moreover, its tuning is reduced to the choice of two real numbers. The performances of the proposed observer...