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This paper studies the event-triggered (ET) H ∞ control of linear networked systems based on static output-feedback. An emulation-based stabilization of the networked system is investigated under the constraints such as (i) quantizations, (ii) network-induced delays, (iii) external disturbances, and (iv) packet losses. In particular, output measurement and control input quantizations, lower and upper bounds of the network-induced delays, bounded external disturbances, and packet losses are carefully taken into account. The process of stability analysis has three steps. In the first step, a quantized ET control is defined, and then three sector-bound methods for logarithmic quantization are formulated. In the second step, the ET-mechanism is described with an input delay model. Based on the model, for two approaches, namely, switching-ET and periodic-ET, the criteria for the exponential stability and L 2 -gain analysis of perturbed networked system are established, respectively. In the third step, a constraint for packet loss effect is provided. In summary, the stability analysis is based on linear matrix inequalities (LMIs) through a Lyapunov-Krasovskii functional method. Finally, the simulation results are given to evaluate the validation of the analysis using two benchmark examples. KEYWORDS event-triggered H ∞ control, network-induced delay, packet loss (dropout), periodic and switching approach, quantization A networked control system (NCS) is a setup including nodes that interact over a signal transaction network for its coordinated operation. With the fast development of Internet, types of wireless communication equipment, and new control schemes, NCSs have been recently paid much attention by researchers. 1,2 Such systems have found many applications in various areas of engineering, including (i) remote control of distributed or non-co-located modern industrial systems such as tele-surgery, tele-operated haptic systems, and tele-robotics, 3 especially remote controlled robots in harmful areas, for instance, nuclear locations, or space, (ii) power systems and smart grids, 4 (iii) multiagent systems, 5 and (iv) vehicle industry and modern automobile. 6 Despite the merits of networks such as flexibility, reduced wireline, easy installation, and low maintenance costs, the possible constraints include limited channel bandwidth, time delay, variable sampling and release intervals, quantization, and packet loss. These constraints lead to performance degradation or even destabilizing NCS. For reducing the network workload, the ET mechanism has been proposed. 1,[7][8][9] In the conventional/continuous ET control, the sampling time is executed after an event, which is generated by some state or/and input dependent condition, whereas, in periodic Optim Control Appl Meth. 2020;41:327-348.wileyonlinelibrary.com/journal/oca

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This paper addresses the stability conditions of the sampled-data teleoperation systems consisting continuoustime master, slave, operator, and environment with discrete-time controllers over general communication networks. The output signals of the slave and master robots are quantized with stochastic sampling periods which are modeled as being from a finite set. By applying an input-delay method, the probabilistic sampling system is converted into a continuoustime system including stochastic parameters in the system matrices. The main contribution of this paper is the derivation of the less conservative stability conditions for linear discrete teleoperation systems taking into account the challenges such as the stochastic sampling rate, constant time delay and the possibility of data packet dropout. The numbers of dropouts are driven by a finite state Markov chain. First, the problem of finding a lower bound on the maximum sampling period that preserves the stability is formulated. This problem is constructed as a convex optimization program in terms of linear matrix inequalities (LMI). Next, Lyapunov-Krasovskii based approaches are applied to propose sufficient conditions for stochastic and exponential stability of closed-loop sampled-data bilateral teleoperation system. The proposed criterion notifies the effect of sampling time on the stability-transparency trade-off and imposes bounds on the sampling time, control gains and the damping of robots. Neglecting this study undermines both the stability and transparency of teleoperation systems. Numerical simulation results are used to verify the proposed stability criteria and illustrate the effectiveness of the sampling architecture.

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SUMMARYThe possibility of operating in remote environments using teleoperation systems has been considered widely in the control literature. This paper presents a review on the discrete-time teleoperation systems, including issues such as stability, passivity and time delays. Using discrete-time methods for a master-slave teleoperation system can simplify control implementation. Varieties of control schemes have been proposed for these systems and major concerns such as passivity, stability and transparency have been studied. Recently, unreliable communication networks affected by packet loss and variable transmission delays have been received much attention. Thus, it is worth considering discrete-time theories for bilateral teleoperation architectures, which are formulated on the same lines as the continuous-time systems. Despite the extensive amount of researches concerning continuous-time teleoperation systems, only a few papers have been published on the analysis and controller design for discrete bilateral forms. This paper takes into account the challenges for the discrete structure of bilateral teleoperation systems and notifies the recent contributions in this area. The effect of sampling time on the stability-transparency trade-off and the task performance is taken into consideration in this review. These studies can help to design guidelines to have better transparency and stable teleoperation systems.