Uniformly ultimately bounded tracking control of sandwich systems with nonsymmetric sandwiched dead-zone nonlinearity and input saturation constraint

This article studies the uniformly ultimately bounded output tracking problem of uncertain nonlinear sandwich systems with sandwiched dead-zone nonlinearity in the presence of some practical constraints such as nonsymmetric input saturation, model uncertainties, time-varying external disturbances, and unknown parameters. Due to the existence of both dead-zone and saturation nonlinearities, the design process is more complicated; therefore, to solve the design complexities, the designing process is divided into two phases. The proposed method leads to output tracking with acceptable accuracy. Moreover, all signals in the closed-loop system are ultimately bounded. Simulation results illustrate the applicability and effectiveness of the proposed method by its application on two practical sandwich systems (robotic system and electrohydraulic servo press system).

A Robust Delay Compensator for Uncertain Nonlinear Systems With Unknown Time-Varying Input Delay

This paper proposes a robust compensator for a class of uncertain nonlinear systems subjected to unknown time-varying input delay. The proposed control law is based on the integral of past values of control and a novel filtered tracking error. Sufficient gain conditions dependent on the known bound of the delay are derived using a Lyapunov-based stability analysis, where Lyapunov–Krasovskii (LK) functionals are used to achieve a global uniformly ultimately bounded (GUUB) tracking result. Simulation results for a nonlinear system are used to evaluate the performance and robustness of the controller for different values of time-varying input delay.

Resilient control of switched systems in conditions of input delay and cyber attacks

The subject of this article is to propose novel resilient control strategies for switched systems in conditions of input delay and cyber-attacks. At first it is assumed that the attacker can access the sensor of the system and consequently injects unknown false data to the sensor. Next, it is assumed that attacker can access the control block channel and consequently injects unknown nonlinear false data to the controller and also simultaneously can access the actuator, resulting in the loss of effectiveness of the actuator. In such conditions, novel resilient control strategies are proposed to keep the performance of the attacked system up to a reasonable security bound. To achieve resilience in such conditions, Lyapunov–Krasovskii functional method is applied to show the uniformly ultimately bounded behavior of the system. Finally, for an evaluating approach, two illustrative examples will be solved.

GLOBAL ATTRACTIVITY AND PERMANENCE OF A STAGE-STRUCTURED PEST MANAGEMENT SI MODEL WITH TIME DELAY AND DISEASED PESTS IMPULSIVE TRANSMISSION

In this work, we consider a stage-structured pest management SI model with time delay and diseased pests impulsive transmission. Sufficient conditions which guarantee the global attractivity of pest-extinction periodic solution and permanence of the system are obtained. We also prove that all solutions of the system are uniformly ultimately bounded. Our results provide reliable tactic basis for the practical pest management.