With the aid of disturbance observer strategy, this article aims to investigate rejection and stabilization problems for periodic piecewise time-varying systems that are subject delays, parameter uncertainties, nonlinear perturbations exogenous disturbances. To be more specific, built by segmenting fundamental period into a limited number subintervals. Further, disturbances engendered from an s...

In this work we deal with the design of the robust feedback control of wastewater treatment system, namely the activated sludge process. This problem is formulated by a nonlinear ordinary differential system. On one hand, we develop a robust analysis when the specific growth function of the bacterium μ is not well known. On the other hand, when also the substrate concentration in the feed strea...

The main issue of this paper is the design of a class of SISO robust control law for the regulation of dissolved oxygen (DO) of an industrial Activated Sludge Wastewater Plant via the air flow rate (non-affine control input). The control design is related with an uncertainty estimator (reduced order observer) based Generic Model Control (GMC). The desired dissolved oxygen trajectory is proposed...

In this paper, a robust sliding mode observer (SMO) design problem is investigated for the purpose of reconstruction of actuator faults in a class of uncertain linear systems. A sufficient condition for the existence and the stability of the SMO is established by solving a set of linear matrix inequalities (LMIs). Also, a new design method for the robust SMO with H∞ techniques is proposed to gu...

This paper presents a systematic design methodology for fuzzy observer-based secure communications of chaotic systems with guaranteed robust performance. The Takagi–Sugeno fuzzy models are given to exactly represent chaotic systems. Then, the general fuzzy model of many well-known chaotic systems is constructed with only one premise variable in fuzzy rules and the same premise variable in the s...