Uncertain Nonlinear Networked Control Systems Research Articles

Self-Triggered $$H_\infty $$ Control for Uncertain Nonlinear Networked Control Systems Under Dynamic Quantization and Packet Dropout

Self-Triggered $$H_\infty $$ Control for Uncertain Nonlinear Networked Control Systems Under Dynamic Quantization and Packet Dropout

Sampled-Data-Based Dissipative Stabilization of IT-2 TSFSs Via Fuzzy Adaptive Event-Triggered Protocol.

In this research, the fuzzy adaptive event-triggered control (FAETC) issue is addressed for uncertain nonlinear networked control systems with network-induced delays (NIDs) and external disturbance. In order to effectively capture parameter uncertainties, the interval type-2 (IT-2) Takagi-Sugeno (T-S) fuzzy model is utilized to represent such a system. Considering the fact that the controller is fuzzy and the threshold can promptly update its state according to the current and latest sampled signals (SSs), it becomes quite challenging to solve the dissipative stabilization problem (DSP) with the existing schemes. Then, a novel FAETC protocol is put forward to reduce the utilization of communication resources while maintaining the desired control performance. By employing the fuzzy-logic technique and the looped Lyapunov functional (LLF) approach, sufficient conditions related to the relationship between the stabilization and desired dissipative performance for the resulting system are formulated. A numerical example is used to validate the feasibility of our attained results.

Dynamic output feedback control for interval type-2 fuzzy systems against DoS attacks and sensor failures

This article focuses on investigating a dynamic output feedback control issue for uncertain nonlinear networked control systems (NCSs) in the presence of Denial-of-Service (DoS) attacks and sensor failures. By using the low and upper membership functions (LUMFs) of interval type-2 (IT2) Takagi-Sugeno (T-S) fuzzy model, the uncertainties existing in the considered NCSs are depicted effectively. Based on the IT2 fuzzy system, a switching fuzzy model is further established to correspond to different DoS attack scenarios. According to the average dwell-time approach and Lyapunov stability theory, an IT2 fuzzy dynamic output feedback control scheme is proposed so that the exponential stability of the considered NCSs can be achieved regardless of DoS attacks and sensor failures. Lastly, illustrative examples are presented to confirm the theoretical results proposed in this paper.

Iterative learning control for uncertain nonlinear networked control systems with random packet dropout

SummaryThis paper proposes a novel networked iterative learning control (NILC) scheme with adjustment factor for a class of discrete‐time uncertain nonlinear systems with stochastic input and output packet dropout modeled as 0‐1 Bernoulli‐type random variable. Firstly, the equivalence relation between the realizability of controlled system and the input‐output coupling parameter (IOCP) is established. Secondly, in order to overcome the main obstacle arising from the unknown IOCP, an identification technique is developed for it. Thirdly, it is strictly proved that, under certain conditions, the tracking errors driven by the developed NILC scheme are convergent to zero along iteration direction in the sense of expectation. Finally, an example is given to demonstrate the effectiveness of the proposed NILC scheme and the merits of adjustment factor.

New Results on the Observer-Based <inline-formula> <tex-math notation="LaTeX">$H_{\infty}$ </tex-math> </inline-formula> Control for Uncertain Nonlinear Networked Control Systems With Random Packet Losses

This paper presents the new results on the H ∞ control of a class of completely uncertain nonlinear networked control systems with random communication packet dropouts, which is partially considered in this paper. The uncertainties in the plant are assumed to be real and time-varying, as well as norm, bounded. The random packet losses are modeled as a Bernoulli distributed white sequence with known conditions on their probability distribution. The controller was designed as an observer-based H ∞ dynamic, such that the closed-loop system is exponentially mean square stable and the effect of the disturbance input on the controlled output is less than a minimum level γ for all admissible uncertainties. New sufficient conditions for the existence of such a controller are presented and proved based on the linear matrix inequalities' approach. The theory presented is illustrated by a numerical example to show the effectiveness of the developed techniques.

Hybrid Active-Passive Robust Fault-Tolerant Control of Event-Triggered Nonlinear NCS

In this paper, the authors aimed to analyze uncertain nonlinear networked control systems (NCS) under discrete event-triggered communication scheme (DETCS), in which an integrated design methodology between robust fault detection observer and active fault-tolerant controller is proposed. Moreover, the problem of hybrid active–passive robust fault-tolerant control, which integrated passive fault-tolerant control, fault detection, and controller reconstruction, is researched. In consideration of the impact of uncertainties and network-induced delay on system performance, a new class of uncertain nonlinear NCS fault model is established based on T-S fuzzy model. By employing Lyapunov stability theory,H∞control theory, and linear matrix inequality method, the fault detection observer and hybrid fault-tolerant controller are both appropriately designed. In addition, the sufficient condition that guaranteed the asymptotically robust stability of nonlinear NCS against any actuator failures is deduced. Finally, a numerical simulation is provided to show the effectiveness of the proposed methods.

Fault‐tolerant control of uncertain non‐linear networked control systems with time‐varying delay, packet dropout and packet disordering

In this study, the fault-tolerant control (FTC) problem is investigated for a class of uncertain non-linear networked control systems with delay, packet dropout, packet disordering and non-linear modelling uncertainty. The deterministic and stochastic faults are considered simultaneously, wherein the plant and sensor faults are modelled as unknown non-linear functions of the state and the health statuses of the actuators are governed by multiple Markovian processes. By considering Markovian delay and packet dropout, a new packet reordering approach is proposed to cope with packet disordering. By utilising adaptive approximation method and adaptive technique, an FTC scheme composed of an FTC component and a fault diagnosis (FD) component is proposed. A theoretical analysis about the stability properties of the FD and FTC components is established. Using information provided by the FD component, the FTC component ensures the boundedness in probability of tracking error. Finally, a simulation example is exploited to show the effectiveness of the proposed method.

Non-Fragile Exponential $H_\infty $ Control for a Class of Nonlinear Networked Control Systems With Short Time-Varying Delay via Output Feedback Controller.

This paper investigates non-fragile exponential H∞ control problems for a class of uncertain nonlinear networked control systems (NCSs) with randomly occurring information, such as the controller gain fluctuation and the uncertain nonlinearity, and short time-varying delay via output feedback controller. Using the nominal point technique, the NCS is converted into a novel time-varying discrete time model with norm-bounded uncertain parameters for reducing the conservativeness. Based on linear matrix inequality framework and output feedback control strategy, design methods for general and optimal non-fragile exponential H∞ controllers are presented. Meanwhile, these control laws can still be applied to linear NCSs and general fragile control NCSs while introducing random variables. Finally, three examples verify the correctness of the presented scheme.

Robust nonlinear variable selective control for networked systems

ABSTRACTThis paper is concerned with the networked control of a class of uncertain nonlinear systems. In this way, Takagi–Sugeno (T-S) fuzzy modelling is used to extend the previously proposed variable selective control (VSC) methodology to nonlinear systems. This extension is based upon the decomposition of the nonlinear system to a set of fuzzy-blended locally linearised subsystems and further application of the VSC methodology to each subsystem. To increase the applicability of the T-S approach for uncertain nonlinear networked control systems, this study considers the asynchronous premise variables in the plant and the controller, and then introduces a robust stability analysis and control synthesis. The resulting optimal switching-fuzzy controller provides a minimum guaranteed cost on an H2 performance index. Simulation studies on three nonlinear benchmark problems demonstrate the effectiveness of the proposed method.

Discrete Event-Triggered Robust Fault-Tolerant Control for Nonlinear Networked Control Systems withα-Safety Degree and Actuator Saturation

This paper deals with the discrete event-triggered robust fault-tolerant control problem for uncertain nonlinear networked control systems (NNCSs) withα-safety degree. A discrete event-triggered communication scheme (DETCS) is initially proposed, and a closed-loop fault model is subsequently established for NNCSs with actuator saturation under the DETCS. Based on an appropriately constructed delay-dependent Lyapunov–Krasovskii function, sufficient conditions are derived to guarantee the asymptotic stability of NNCSs under two different event-triggered conditions and are established as the contractively invariant sets of fault tolerance withα-safety degree. Furthermore, codesign methods between the robust fault-tolerant controller and event-triggered weight matrix are also proposed in terms of linear matrix inequality. The simulation shows that the resultant closed-loop fault NNCSs possesses a high safety margin, and an improved dynamic performance, as well as a reduced communication load. A comparative analysis of the two event-triggered conditions is discussed in the experiment section.

Exploiting packet size in uncertain nonlinear networked control systems

This paper addresses the problem of stabilizing uncertain nonlinear plants over a shared limited-bandwidth packet-switching network. While conventional control loops are designed to work with circuit-switching networks, where dedicated communication channels provide almost constant bit rate and delay, many networks, such as Ethernet, organize data transmission in packets, carrying larger amounts of information at less predictable rates. We adopt a model-based approach to remotely compute a predictive control signal on a suitable time horizon. By exploiting the inherent packets payload, this technique effectively reduces the bandwidth required to guarantee stability. Communications are assumed to be ruled by a rather general protocol model, which encompasses many protocols used in practice. An explicit bound on the combined effects of the maximum time between consecutive accesses to each node (MATI) and the transmission and processing delays (MAD), for both measurements and control packets, is provided as a function of the basin of attraction and the model accuracy. Our control strategy is shown to be robust with respect to sector-bounded uncertainties in the plant model. Sampling of the control signal is also explicitly taken into account. A case study is presented which enlightens the great improvements induced by the packet-based control strategy over methods that send a single control value in each packet.

Robust disturbance attenuation for uncertain nonlinear networked control systems

This paper considers the problem of robust disturbance attenuation for a class of uncertain nonlinear networked control systems. Takagi-Sugeno fuzzy models are firstly employed to describe the nonlinear plant. Markov processes are used to model the random network-induced delays and data packet dropouts. The Lyapunov-Razumikhin method has been used to derive such a controller for this class of nonlinear systems such that it is stochastically stabilizable with a disturbance attenuation level. Sufficient conditions for the existence of such a controller are derived in terms of the solvability of bilinear matrix inequalities. An iterative algorithm is proposed to change this non-convex problem into quasi-convex optimization problems, which can be solved effectively by available mathematical tools. The effectiveness of the proposed design methodology is verified by a numerical example.

Non-fragile control for nonlinear networked control systems with long time-delay

This paper considers the non-fragile control problem for uncertain nonlinear networked control systems (NCSs) with long time-delay and controller gain perturbations. Firstly, the NCS model with random long time-delay is transformed into a discrete-time system model with uncertain parameters. Then, the Lyapunov stability theory and the linear matrix inequality (LMI) approach are applied to design a non-fragile controller, which results in the closed-loop system being asymptotically stable and the system’s cost function value being less than a determinate upper bound. At the same time, the existence condition and the design approach of a non-fragile controller are presented. Finally, simulation examples are employed to verify the validity of the proposed control algorithm.

Robust stabilization for a class of nonlinear networked control systems

The problem of robust stabilization for a class of uncertain networked control systems (NCSs) with nonlinearities satisfying a given sector condition is investigated in this paper. By introducing a new model of NCSs with parameter uncertainty, network-induced delay, nonlinearity and data packet dropout in the transmission, a strict linear matrix inequality (LMI) criterion is proposed for robust stabilization of the uncertain nonlinear NCSs based on the Lyapunov stability theory. The maximum allowable transfer interval (MATI) can be derived by solving the feasibility problem of the corresponding LMI. Some numerical examples are provided to demonstrate the applicability of the proposed algorithm.

T-S Fuzzy-Model-Based Robust $H_{\infty}$ Design for Networked Control Systems With Uncertainties

This paper concerns a problem of robust Hinfin control for a class of uncertain nonlinear networked control systems (NCSs), which can be represented by a T-S fuzzy model with uncertainties. Both network-induced delay and packet dropout are addressed. The controller design method is presented based on a delay-dependent approach, and the robust Hinfin controller gain matrices are obtain by solving a set of linear matrix inequalities (LMIs). Moreover, a general Lyapunov-Krasovskii functional is used, and some slack matrices, which bring much flexibility in solving LMIs, are introduced during the proof. Simulation results show the validity of the proposed method.