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This paper introduces a robust method for estimating states and switching signals in impulsive switched systems with unknown inputs. It uses a reduced-order estimator to handle inaccessible states and an output derivative-based method to address the effects of unknown inputs, even though this adds some impulsive effects. The method is divided into two main steps: first, dedicated estimators determine the switching signal and identify the active subsystem; then, state estimation is carried out. By incorporating the estimated switching signal, the method effectively eliminates impulsive effects caused by unknown inputs. The study also explores the key conditions needed to ensure that estimation errors decrease exponentially. It uses a common Lyapunov function and Linear Matrix Inequality techniques. Simulation results show that this method is both efficient and effective, outperforming single-estimator approaches., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 ISA. Published by Elsevier Ltd. All rights reserved.)

This paper investigates an event-triggered control method for a class of nonlinear multi-agent systems, in which a group of followers surround a group of leaders. Dynamics of leaders and followers are assumed to be heterogeneous and to have unknown parameters. To deal with this problem, some adaptive laws and also controllers including event-triggered estimator of leaders' geometric center are proposed. In order to reduce some dispensable data exchange among the follower agents and save the limited communication resources, event-triggered control protocols are used to attain better performance of resources. The proposed control scheme guarantees that all the closed loop signals are globally bounded and surrounding error converges toward a compact set, exponentially. Moreover, Zeno behavior is also excluded under certain conditions. Eventually, numerical simulations are provided to verify theoretical results and demonstrate that the triggering laws cause decrement of the number of controller updates and inter-agent communications., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 ISA. Published by Elsevier Ltd. All rights reserved.)

This paper develops the stability analysis for linear bilateral teleoperation systems exposed to communication constraints and multirate samplers. Dynamics of the master and slave robots are assumed to be continuous-time with discrete-time controllers. The proposed multirate design guarantees the exponential stability of the teleoperation system over a communication networks. Different sampling rates are imposed on position/velocity signals in both master and slave sides and by exerting input-delay approach, the multirate dynamics is transformed into a continuous-time system. Sufficient Krasovskii-based stability criteria are provided to preserve the exponential stability of the linear discrete-time system for asynchronously sampling intervals and update rates. This analysis is formulated as a convex optimization problem in terms of linear matrix inequalities (LMI) to calculate the longest interval between two successive sampling periods. The proposed multirate approach demonstrates that selecting adequate intervals for samplers and proper update rates for actuators has a considerable effect on the stability of the system. In order to validate the stability criteria and present the efficacy of the proposed multirate scheme, pair of two degree of freedom manipulators will be investigated and maximum allowable sampling periods and update rates are computed to preserve the exponential stability for different multirate cases., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 ISA. Published by Elsevier Ltd. All rights reserved.)

In this paper, the surrounding control problem of a group of non-identical agents is considered, where a team of followers achieves an equidistant distributed formation to surround a team of moving leaders. An adaptive design method is presented for multi-agent systems where the dynamics of agents are supposed to be nonlinear with unknown parameters. First, an estimator for the center of the leaders is introduced. Then, two distributed adaptive controllers based on the estimated center are proposed for each follower. The stability and parameter convergence of the proposed protocols are shown by using algebraic graph theory and Lyapunov theory. Finally, a numerical example is provided to validate the theoretical results., (Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.)

A novel trilateral control architecture for Dual-master/Single-slave teleoperation system with taking account of saturation in actuators, nonlinear dynamics for telemanipulators and bounded varying time delay which affects the transmitted signals in the communication channels, is proposed in this paper. In this research, we will address the stability and desired position coordination problem of trilateral teleoperation system by extension of (nP+D) controller that is used for Single-master/Single-slave teleoperation system. Our proposed controller is weighted summation of nonlinear Proportional plus Damping (nP+D) controller that incorporate gravity compensation and the weights are specified by the dominance factor, which determines the supremacy of each user over the slave robot and over the other user. The asymptotic stability of closed loop dynamics is studied using Lyapunov-Krasovskii functional under conditions on the controller parameters, the actuator saturation characteristics and the maximum values of varying time delays. It is shown that these controllers satisfy the desired position coordination problem in free motion condition. To show the effectiveness of the proposed method, a number of simulations have been conducted on a varying time delay Dual-master/Single-slave teleoperation system using 3-DOF planar robots for each telemanipulator subjected to actuator saturation., (Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.)