In this paper, a modular observer design methodology is formulated for nonlinear systems with partial model knowledge. Our consists of three phases: (i) an initial robust that enables one to learn the dynamics without allowing state estimation error diverge (hence, safe); (ii) learning phase wherein unmodeled components are estimated using Gaussian process-based Bayesian optimization; and, (iii...

Recently Kazantzis-Kravaris and Kreisselmeier-Engel have suggested two apparently different approaches to constructing observers for nonlinear systems. We show that these approaches are closely related and lead to observers with linear error dynamics in transformed variables. In particular we give sufficient conditions for the existence of smooth solutions to the Kazantzis-Kravaris PDE.

In this study, we develop fuzzy adaptive tracking control via two-layer fuzzy observers, variable structure systems (VSS), and H∞ control algorithm for nonlinear systems with plant uncertainties, output delays, and external disturbances. The Takagi–Sugeno fuzzy dynamic model with adaptation capability is used to approximate the nonlinear system. When the system states are not available, the sta...

This paper proposes a sliding-mode control scheme for a class of nonlinear systems with multiple time delays, in the state variables and in the output signal. The unmeasured state of the system is estimated by an asymptotic observer for the zero dynamics and high-gain observers connected in cascade for a chain of integrators with a nonlinear input disturbance which compose the complete state. T...

In a bioprocess it is desired to produce high amounts of biomass or metabolites such as vitamins, antibiotics, and ethanol, among others. The measurement of biological parameters as the cell, by-product concentrations and the specific growth rate are essential to the successful monitoring and control of bioprocesses (Horiuchi & Kishimoto, 1998). Adequate control of the fermentation process redu...

A robust high gain observer for state and unknown inputs/faults estimations for a special class of nonlinear systems is developed in this article. Ensuring the observability of the faults/unknown inputs with respect to the outputs, the faults can be estimated from the sliding surface. Under a Lipschitz condition for the nonlinear part, the high gain observers are designed under some regularity ...

This paper is concerned with the problem of  H observer design for a class of time-delay nonlinear systems with external disturbance. The purpose of this problem is to design a  H observers such that, for the addressed nonlinearities as well as all admissible external disturbance in state equation, the observation process remains globally exponentially stable, independently of the time delay....

— In this paper, our recent work on robust model-based fault diagnosis (FD) for several satellite control systems using learning and sliding mode approaches are summarized. Firstly, a variety of nonlinear mathematical models for these satellite control systems are described and analyzed for the purpose of fault diagnosis. These satellite control systems are classified into two classes of nonlin...

The estimation problem for uncertain time-delay systems is addressed. A design method of reduced-order interval observers is proposed. The observer estimates the set of admissible values (the interval) for the state at each instant of time. The cases of known fixed delays and uncertain time-varying delays are analyzed. The proposed approach can be applied to linear delay systems and nonlinear t...

Abs t r ac t In this paper, we establish that detectability is a necessary condition for the existence of general observers (asymptotic or exponential) for discrete-time nonlinear systems. Using this necessary condition, we show that there does not exist any general observer (asymptotic or exponential) for discrete-time nonlinear systems with real parametric uncertainty, if the state equilibriu...