Effect Of Network-induced Delay Research Articles

Stochastic Robust H∞ Decentralized Network Formation Tracking Control of Large-Scale Team Satellites via Event-Triggered Mechanism

The team formation of large-scale satellites for communication services of future smart cities in the 5G and 6G era is an important research topic currently. In this study, a robust H∞ with an event-triggered mechanism is proposed for the formation of large-scale satellites for communication tasks. At first, a satellite in the team formation is described by a nonlinear stochastic system with intrinsic random fluctuation, external disturbance, and coupling from other satellites. The proposed team formation tracking control for each satellite needs to consider the effect of network-induced delay and packet-dropout as well as save communication resources via an event-triggered mechanism. Further, the desired team formation of large-scale satellites can be prescribed by a set of reference models with the desired formation shape embedded in their reference inputs. Therefore, the large-scale team formation design problem can be simplified as an independentH∞ network model reference tracking control design problem for each satellite to efficiently attenuate the worst-effect of external disturbance, coupling of other satellites, intrinsic random fluctuation, network-induced delay, and packet-dropout on the model reference tracking performance. In order to avoid solving a nonlinear partial differential Hamillion-Jacobin inequality(HJI) for the H∞ decentralized network formation control for each satellite in the team the formation, the T-S fuzzy model is employed to interpolate several local linearized systems to approximate nonlinear satellite systems. Then the HJI in the H∞ decentralized network team formation design problem can be transformed into a set of linear matrix inequalities (LMIs) which can be easily solved by LMI TOOLBOX in MATLAB. Finally, a simulation example of team formation composed of ten satellites is given to illustrate the design procedure and to validate the proposed method in comparison with other methods.

Enhancing disturbance rejection performance for a class of networked cascade control systems: an H∞ approach

The emergence and integration of communication technologies in industrial control systems has created new requirements in terms of stability, performance and robustness that should be met to deal with the effects of network-induced delays. In this paper, the analytical design of a networked cascade control system exposed to communication delay and data dropout is investigated. First, an appropriate augmented continuous-time state-space model is proposed. Then, a mathematical approach is introduced to implement the augmented Lyapunov-Krasovskii functional and free-weighting matrix technique for the stability analysis purpose. The augmented representation simplifies the stability analysis of these systems significantly and makes it possible to correlate different variables in Lyapunov functional, which causes a remarkable improvement in H ∞ performance. Numerical simulations are presented to validate the feasibility and performance of the proposed approach. The obtained results indicate achieving much higher allowable delay bounds and robustness against disturbances.

Event-Triggered-Based External Consensus Protocol of RBF-ARX-Model-Based Networked Multiagent Systems with Nonlinear Dynamics and Communication Delays

An event-triggered-based external consensus control protocol with delay compensation for networked multiagent systems (NMASs) with nonlinear dynamics and network-induced delays is discussed in this paper. An RBF-ARX modelling method is adopted to approximate a nonlinear system. By utilizing the RBF-ARX model, the locally linearized time series model can be obtained to describe the behaviour of agents with nonlinear characteristics. An event-triggered control protocol with communication delay compensation is proposed to reduce the effects of network-induced delays and the times of the agent’s control update and communication between others by applying the idea of a prediction strategy. The event-triggered mechanism for each agent only depends on the deviation between its own output and the delay-compensated output of neighboring agents. Then, a distributed event-triggered-based and delay-compensated external consensus control protocol is given. Under this proposed control protocol, both the consensus and stability of the system can be proved. Finally, a numerical simulation is performed to verify the availability of our results.

Event-triggered control for networked nonlinear semi-Markovian jump systems with randomly occurring uncertainties and transmission delay

This paper is concerned with stochastic stabilization problem for networked semi-Markovian jump systems with randomly occurring uncertainties and nonlinearities under event-triggered scheme. By employing the delay system method, the stochastic stability analysis and controller synthesis for semi-Markovian jump systems considering the effect of network-induced delay are presented. In order to reduce the frequency of data transmission and save network resources, sampled-data-based event-triggered scheme is utilized. Mode-dependent Lyapunov-–Krasovskii functional candidate is constructed and free-weighting matrix method is employed which can reduce some conservativeness of the results. Then, novel conditions are formulated to ensure the stochastic stability for stochastic semi-Markovian jump time-delay systems in terms of linear matrix inequalities(LMIs). Controller gain matrices and event-triggered matrices can be co-designed simultaneously based on the obtained sets of LMIs. Finally, simulations are given to illustrate the effectiveness of the results.

New Smith predictive fuzzy immune PID control algorithm for MIMO networked control systems

Aiming at the problem of network-induced delays for multi-input multi-output networked control systems (MIMO NCS), a new Smith predictive fuzzy immune PID algorithm is introduced to effectively reduce the adverse effect of network-induced delays about stability in MIMO NCS, firstly, by using the v-norm type to decouple the coupling plant. Based on the generalized plant after decoupling, the new Smith predictor is designed. Then, an modified fuzzy immune feedback control algorithm is used to tune PID controller parameters online. When there is a model mismatch or parameter perturbation, the set-point tracking performance and robustness of output response can be significantly optimized. The proposed algorithm does not contain the network delay prediction model and does not need to measure, estimate, or identify the network delay. It can be used in MIMO NCS where the network bandwidth is constrained and the network-induced delays are large. Numerical examples with Ethernet protocol are built to illustrate the correctness and effectiveness of this new algorithm.

Network-Based Practical Consensus of Heterogeneous Nonlinear Multiagent Systems.

This paper studies network-based practical leader-following consensus problem of heterogeneous multiagent systems with Lipschitz nonlinear dynamics under both fixed and switching topologies. Considering the effect of network-induced delay, a network-based leader-following consensus protocol with heterogeneous gain matrix is proposed for each follower agent. By employing Lyapunov-Krasovskii method, a sufficient condition for designing the network-based consensus controller gain is derived such that the leader-following consensus error exponentially converges to a bounded region under a fixed topology. Correspondingly, the proposed design approach is then extended to the case of switching topology. Two numerical examples with networked Chua's circuits are given to show the efficiency of the design method proposed in this paper.

Research on Fuzzy Immune Self-Adaptive PID Algorithm Based on New Smith Predictor for Networked Control System

We first analyze the effect of network-induced delay on the stability of networked control systems (NCSs). Then, aiming at stochastic characteristics of the time delay, we introduce a new Smith predictor to remove the exponential function with the time delay in the closed-loop characteristic equation of the NCS. Furthermore, we combine the fuzzy PID algorithm with the fuzzy immune control algorithm and present a fuzzy immune self-adaptive PID algorithm to compensate the influence of the model deviation of the controlled object. At last, a kind of fuzzy immune self-adaptive PID algorithm based on new Smith predictor is presented to apply to the NCS. The simulation research on a DC motor is given to show the effectiveness of the proposed algorithm.

Event-triggered [formula omitted] stabilization for networked stochastic systems with multiplicative noise and network-induced delays

This paper is concerned with event-triggered H∞ stabilization (in the mean square sense) for networked stochastic system with multiplicative noise and network-induced delays. Firstly, a new discrete event-triggered transmission protocol (DETTP) is proposed to reduce the utilization rate of communication bandwidth. The main features of the proposed protocol involve three aspects: (1) it allows the presence of external disturbances and multiplicative noise; (2) it is more general than some existing event-triggered transmission schemes in the deterministic setting; and (3) the minimum inter-event time is implicity defined and is naturally given by the sampling period chosen for the plant. Secondly, under the DETTP, a new closed-loop stochastic networked control system model is established. Remarkably, to facilitate theoretical analysis, the resultant event-based stochastic networked control system is further transformed into a system with two successive delay components in the state, considering the effects of network-induced delays, multiplicative noise and DETTP in a unified framework. By using stochastic system theory, sufficient conditions on the existence of the desired event-based H∞ state feedback controller are derived such that the resultant event-based stochastic networked control system is exponentially stable in the mean square sense with a prescribed H∞ performance while reducing the number of sampled-state transmission along the feedback link as much as possible. Thirdly, a co-design algorithm for determining the parameters of the DETTP and the state feedback controller gain matrix are also proposed. Finally, two practical examples are given to illustrate the effectiveness and advantage of the proposed method over some existing results in the literature.

Joint Design of Control and Power Efficiency in Wireless Networked Control System

This paper presents a joint design method for wireless networked control system (WNCS) to balance both the demands of network service and the control performance. Since the problems of power consumption, communication reliability, and system stability exist simultaneously and interdependently in WNCS, most of the achieved results in the wireless network and wired networked control system cannot be used directly. To coordinate the three problems, sampling period is found to be the linking bridge. An adaptive sampling power efficiency algorithm is proposed to manage the power consumption such that it can meet the demands of network life span. The sampling period is designed to update periodically on the constraints of network schedulability and system stability. The convergence of the power efficiency algorithm is further proved. The sampling period is no longer a fixed value, however; thus, increasing the difficulty in modeling and controlling such a complicated time-varying system remains. In this work, a switched control system scheme is applied to model such a WNCS, and the effect of network-induced delay is considered. Switched feedback controllers are introduced to stabilize the WNCS, and some considerations on stability condition and the bounds of the update circle for renewing sampling period are discussed. A numerical example shows the effectiveness of the proposed method.

A normalized PID controller in networked control systems with varying time delays

It requires not only simplicity and flexibility but also high specified stability and robustness of system to design a PI/PID controller in such complicated networked control systems (NCSs) with delays. By gain and phase margins approach, this paper proposes a novel normalized PI/PID controller for NCSs based on analyzing the stability and robustness of system under the effect of network-induced delays. Specifically, We take into account the total measured network delays to formulate the gain and phase margins of the closed-loop system in the form of a set of equations. With pre-specified values of gain and phase margins, this set of equations is then solved for calculating the closed forms of control parameters which enable us to propose the normalized PI/PID controller simultaneously satisfying the following two requirements: (1) simplicity without re-solving the optimization problem for a new process, (2) high flexibility to cope with large scale of random delays and deal with many different processes in different conditions of network. Furthermore, in our method, the upper bound of random delay can be estimated to indicate the operating domain of proposed PI/PID controller. Finally, simulation results are shown to demonstrate the advantages of our proposed controller in many situations of network-induced delays.

An auction-based dynamic bandwidth allocation with sensitivity in a wireless networked control system

Applications of control systems on wireless networks have been widely utilized due to their mobility. However, the performances of these networked control systems (NCS) could be degraded and become unstable by network-induced delays. Existing dynamic bandwidth allocation methods for NCS assign bandwidth to each system with respect to different priorities in an ascending order. However, these NCS may not be given bandwidths at equilibrium such that each of these NCS is satisfied with respect to bandwidth requests of other NCS. Therefore, some NCS may always consume most of given bandwidths, while others may never be given satisfied bandwidths. This paper proposes a dynamic bandwidth allocation methodology that controls bandwidths given to open-loop NCS to be at Nash equilibrium. In this paper, the average sensitivities of NCS are used in utility functions in order to evaluate the effects of network-induced delays for NCS. Then, a control center or an access point will use the proposed methodology to allocate bandwidths for all NCS based on Nash equilibrium. Simulations and experiments were setup from a set of DC motors controlled over a wireless network. Simulation and experimental results show good performances of the proposed methodology compared with three other methods.