In this paper, a practical state estimation strategy against joint sensor and actuator attacks is proposed for cyber-physical systems (CPSs). The CPSs are formulated based on delta operator for the requirement of real control systems with high-sampling or variable-sampling periods. The attacks fulfilling sparse observation condition are supposed to be randomly injected into both sensor and actuator units. Various numbers of attacks on sensors and actuators can be properly handled. Based on multiple observations of the attacked measurements, a new estimator in delta-domain is proposed to estimate the states of the attacked CPS. The convergence of the corresponding estimation error is analyzed based on pole assignment analysis and some matrix equality constraints. Further, by utilization of a dissipativity approach, estimator-based time-driven controller and self-triggered controller are designed for the enhancement of the estimations and the resource saving. Simulations for the joint attack scenario are provided to testify the applicability and effectiveness of the proposed estimation methods.

In this research article, the finite-time asynchronous sliding mode control (SMC) scheme for Markovian jump systems (MJSs) subject to sensor and actuator faulty signals, is investigated based on the average dwell time approach. Firstly, an asynchronous stochastic hybrid model is proposed in the light of the existing non-synchronization phenomenon of unmeasurable state and indirect access to jump information of original systems. The average dwell time technique, which has the ability to compensate the effects of arbitrary switching by generating a sequence of signals to regulate/choose an appropriate feedback Markov switching signal among the Markov chains, is developed during the reaching phase and sliding motion phase of the sliding mode dynamics. Secondly, based on the asynchronous stochastic hybrid model, a mode-dependent sliding mode surface function is designed. Moreover, the SMC law is synthesized such that the system state trajectories can be driven onto the specified sliding surface in a prescribed limited time. Thirdly, the finite-time analysis method combining with a mode-dependent Lyapunov function, which can reduce drastically the design conservatism, is adopted to guarantee the finite-time boundedness of the sliding mode dynamics both in the reaching phase and sliding motion phase. Fourthly, sufficient conditions are interpreted for the solutions of asynchronous controller gain matrices and an algorithm is provided to assist computing the SMC gain as an auxiliary tool. Finally, a numerical example is given to illustrate the effectiveness of the proposed new design techniques.

In this work, a novel discrete-time fractional-order sliding mode control (SMC) scheme is proposed, which guarantees the desired tracking performance of a linear motor control system. By using Euler’s discretization method, a discrete-time model is firstly established for the linear motor, which includes the nonlinear friction and the uncertainties. Considering the practicability of the engineering application, a new discrete-time fractional-order sliding surface is constructed by taking the Grünwald–Letnikov definition based fractional-order difference of the tracking error into account. Compared to the classical integer-order sliding surface, by the proposed fractional-order sliding surface in this work, a better performance can be achieved due to the memory effect of the fractional calculus. To drive the system trajectories to the predefined sliding surface in finite sampling steps, a novel equivalent control is then designed, which can adjust the switching control input adaptively. Meanwhile, the theoretical analysis for the tracking error of the linear motor system is presented, and the practical reachability of the sliding surface is validated by numerical simulations. Finally, the effectiveness of the proposed control strategy is verified by a group of tracking experiments on a linear motor platform.

This paper is concerned with event-triggered sliding mode control (SMC) for uncertain stochastic systems subject to limited communication capacity. We consider the stochastic perturbation, exogenous disturbance and the network-induced communication constraints in a whole framework of SMC design. The measurable output is adequately sampled for periodic computation of a designed event trigger. Network-induced delays are characterized in the transmission over a shared network communication from sensor to controller. An event-triggered zero-order-hold (ZOH) is employed to keep receiving and sending the delayed measurement for control updating, and a state observer is designed to estimate the system state and to facilitate the design of sliding surface. Then, based on the measurement and observer’s outputs, a novel SMC law is presented. The stochastic stability for the overall closed-loop system is analyzed, and the exogenous disturbance is attenuated in an sense. Furthermore, the presented event-triggered SMC methods are successfully applied to multi-loop control case considering shared communication limitation. Simulation results are provided to verify the effectiveness of the proposed design scheme.

In this paper, the problems of stability analysis and stabilization are investigated for discrete-time two-dimensional (2-D) switched systems, which are formulated by the well-known Fornasini–Marchesini local state-space model. Firstly, by using the switched quadratic Lyapunov function approach, a sufficient stability condition is established for such systems under arbitrary switching signal. Then, the extended average dwell time technique combining with the piecewise Lyapunov function approach is developed, and it is utilized for the stability analysis of the 2-D switched systems for the restricted switching case. Based on the stability analysis results, sufficient conditions are presented to stabilize the 2-D switched systems. Finally, two examples are provided to illustrate the effectiveness of the proposed new design techniques.