Distributed Fault Estimation for Nonlinear Systems With Sensor Saturation and Deception Attacks Using Stochastic Communication Protocols

This paper is aimed at the distributed fault estimation issue associated with the potential loss of actuator efficiency for a type of discrete-time nonlinear systems with sensor saturation.For the distributed estimation structure under consideration,an estimation center is not necessary,and the estimator derives its information from itself and neighboring nodes,which fuses the state vector and the measurement vector.In an effort to cut down data conflicts in communication networks,the stochastic communication protocol(SCP)is employed so that the output signals from sensors can be selected.Additionally,a recursive security estimator scheme is created since attackers randomly inject malicious signals into the selected data.On this basis,sufficient conditions for a fault estimator with less conservatism are presented which ensure an upper bound of the estimation error covariance and the mean-square exponential boundedness of the estimating error.Finally,a numerical example is used to show the reliability and effectiveness of the considered distributed estimation algorithm.

Event-triggered leader-following formation control for multi-agent systems under communication faults: application to a fleet of unmanned aerial vehicles

The main contribution of this paper is the design of an event-triggered formation control for leader-following consensus in second-order multi-agent systems(MASs)under communication faults.All the agents must follow the trajectories of a virtual leader despite communication faults considered as smooth time-varying delays dependent on the distance between the agents.Linear matrix inequalities(LMIs)-based conditions are obtained to synthesize a controller gain that guarantees stability of the synchronization error.Based on the closed-loop system,an event-triggered mechanism is designed to reduce the control law update and information exchange in order to reduce energy consumption.The proposed approach is implemented in a real platform of a fleet of unmanned aerial vehicles(UAVs)under communication faults.A comparison between a state-of-the-art technique and the proposed technique has been provided,demonstrating the performance improvement brought by the proposed approach.

Learning-Based Switched Reliable Control of Cyber-Physical Systems With Intermittent Communication Faults

This study deals with reliable control problems in data-driven cyber-physical systems(CPSs) with intermittent communication faults, where the faults may be caused by bad or broken communication devices and/or cyber attackers. To solve them, a watermark-based anomaly detector is proposed, where the faults are divided to be either detectable or undetectable.Secondly, the fault's intermittent characteristic is described by the average dwell-time(ADT)-like concept, and then the reliable control issues, under the undetectable faults to the detector, are converted into stabilization issues of switched systems. Furthermore,based on the identifier-critic-structure learning algorithm, a datadriven switched controller with a prescribed-performance-based switching law is proposed, and by the ADT approach, a tolerated fault set is given. Additionally, it is shown that the presented switching laws can improve the system performance degradation in asynchronous intervals, where the degradation is caused by the fault-maker-triggered switching rule, which is unknown for CPS operators. Finally, an illustrative example validates the proposed method.

Optimization of communication topology for persistent formation in case of communication faults

To address the optimization problem of communication topology for persistent formation in the case of communication faults such as link interruption,transmitter failure,and receiver failure a two-stage model including fast reconstruction of communication topology and re-optimization of communication topology is constructed.Then,a fast reconstruction algorithm of communication topology for persistent formation(FRA-CT-PF),based on optimally rigid graph,arc addition operation,and path reversal operation,is proposed,which can quickly generate a feasible reconstructed communication topology after communication faults,thus ensuring the safety of the agents and maintaining the formation shape of persistent formation.Furthermore,a re-optimization algorithm of communication topology for persistent formation(ROA-CTPF),based on agent position exchange,is proposed,which can further obtain a reoptimized communication topology to minimize the formation communication cost while still maintaining the formation shape of persistent formation.The time complexities of these two algorithms are also analyzed.Finally,the effectiveness of the above algorithms is verified by numerical experiments.Compared with existing algorithms,FRA-CT-PF can always obtain feasible reconstructed communication topology in much less time under all communication fault scenarios,and ROA-CT-PF can obtain a reoptimized communication topology to further reduce the formation communication cost in a shorter time.

Containment-Based Multiple PCC Voltage Regulation Strategy for Communication Link and Sensor Faults

The distributed AC microgrid(MG) voltage restoration problem has been extensively studied. Still, many existing secondary voltage control strategies neglect the co-regulation of the voltage at the point of common coupling(PCC) in the AC multi-MG system(MMS). When an MMS consists of sub-MGs connected in series, power flow between the sub-MGs is not possible if the PCC voltage regulation relies on traditional consensus control objectives. In addition, communication faults and sensor faults are inevitable in the MMS. Therefore, a resilient voltage regulation strategy based on containment control is proposed.First, the feedback linearization technique allows us to deal with the nonlinear distributed generation(DG) dynamics, where the PCC regulation problem of an AC MG is transformed into an output feedback tracking problem for a linear multi-agent system(MAS) containing nonlinear dynamics. This process is an indispensable pre-processing in control algorithm design. Moreover, considering the unavailability of full-state measurements and the potential faults present in the sensors, a novel follower observer is designed to handle communication faults. Based on this, a controller based on containment control is designed to achieve voltage regulation. In regulating multiple PCC voltages to a reasonable upper and lower limit, a voltage difference exists between sub-MGs to achieve power flow. In addition, the secondary control algorithm avoids using global information of directed communication network and fault boundaries for communication link and sensor faults. Finally, the simulation results verify the performance of the proposed strategy.

Resilient Fault Diagnosis Under Imperfect Observations–A Need for Industry 4.0 Era

In smart industrial systems,in many cases,a fault can be captured as an event to represent the distinct nature of subsequent changes.Event-based fault diagnosis techniques are capable model-based methods for diagnosing faults from a sequence of observable events executed by the system under diagnosis.Most event-based diagnosis techniques rely on perfect observations of observable events.However,in practice,it is common to miss an observable event due to a problem in sensorreadings or communication/transmission channels.This paper develops a fault diagnosis tool,referred to as diagnoser,which can robustly detect,locate,and isolate occurred faults.The developed diagnoser is resilient against missed observations.A missed observation is detected from its successive sequence of events.Upon detecting a missed observation,the developed diagnoser automatically resets and then,asynchronously resumes the diagnosis process.This is achieved solely based on postreset/activation observations and without interrupting the performance of the system under diagnosis.New concepts of asynchronous detectability and asynchronous diagnosability are introduced.It is shown that if asynchronous detectability and asynchronous diagnosability hold,the proposed diagnoser is capable of diagnosing occurred faults under imperfect observations.The proposed technique is applied to diagnose faults in a manufacturing process.Illustrative examples are provided to explain the details of the proposed algorithm.The result paves the way towards fostering resilient cyber-physical systems in Industry4.0 context.

Research on Remote Fault Detection System of Ceramic Kiln Based on 5G and IoT Technologies

In order to overcome the defects of the existing technology that the detection of ceramic electric kiln faults takes a long time and costs a lot,an electric kiln control and fault detection device was designed.The working process of the device includes detection module,control module,start⁃stop module and switch module.The detection module detects the resistance circuit and sends a fault signal to the control module.The control module generates stop signal and fault information according to the fault signal,and starts the electric kiln when the fault signal is not received within the preset time.The start⁃stop module can monitor the internal temperature of the electric kiln and control the closing status of the switch module.The switch module is used to control the connection status of AC power and each resistance circuit in the kiln.Based on the 5G DTU or 5G module,the control module could send the information to mobile terminal under the ultra⁃reliable and low⁃latency communication(uRLLC)technical characteristics of 5G communication.

Fault Tolerance and Recovery for Group Communication Services in Distributed Networks

Group communication services （GCSs） are becoming increasingly important as a wide field of promising applications has emerged to serve millions of users distributed across the world.However,it is challenging to make the service fault tolerance and scalable to fulfill the voluminous demand of users in a distributed network （DN）.While many reliable group communication protocols have been dedicated to addressing such a challenge so as to accommodate the changes in the network,they are often costly or require complicated strategies to handle the service interruptions caused by node departures or link failures,which hinders the service practicability.In this paper,we present two schemes to address the challenges.The first one is a location-aware replication scheme called NS,which makes replicas in a dispersed fashion that enables the services on nodes to gain immunity of failures with different patterns （e.g.,network partition and single point failure） while keeping replication overhead low.The second one is a novel failure recovery scheme that exploits the independence between service recovery and structure recovery in time domain to achieve quick failure recovery.Our simulation results indicate that the two proposed schemes outperform the existing schemes and simple alternative schemes in service success rate,recovery latency,and communication cost.

Distributed fault-tolerant strategy for electric swing system of hybrid excavators under communication errors

A distributed fault-tolerant strategy for the controller area network based electric swing system of hybrid excavators is proposed to achieve good performance under communication errors based on the adaptive compensation of the delays and packet dropouts. The adverse impacts of communication errors are effectively reduced by a novel delay compensation scheme, where the feedback signal and the control command are compensated in each control period in the central controller and the swing motor driver, respectively, without requiring additional network bandwidth. The recursive least-squares algorithm with forgetting factor algorithm is employed to identify the time-varying model parameters due to pose variation, and a reverse correction law is embedded into the feedback compensation in consecutive packet dropout scenarios to overcome the impacts of the model error. Simulations and practical experiments are conducted. The results show that the proposed fault-tolerant strategy can effectively reduce the communication-error-induced overshoot and response time variation.

Robust EPR-pairs-based quantum secure communication with authentication resisting collective noise

This work presents two robust quantum secure communication schemes with authentication based on Einstein-Podolsky-Rosen(EPR) pairs, which can withstand collective noises. Two users previously share an identity string representing their identities. The identity string is encoded as decoherence-free states(termed logical qubits), respectively, over the two collective noisy channels, which are used as decoy photons. By using the decoy photons, both the authentication of two users and the detection of eavesdropping were implemented. The use of logical qubits not only guaranteed the high fidelity of exchanged secret message, but also prevented the eavesdroppers to eavesdrop beneath a mask of noise.

Deep Reinforcement Learning Based Resource Allocation for Fault Detection with Cloud Edge Collaboration in Smart Grid

Real-time fault detection is important for operation of smart grid.It has become a trend of future development to design an anomaly detection system based on deep learning by using the powerful computing power of the cloud.However,delay of Internet transmission is large,which may make the delay time of detection and transmission go beyond the limits.However,the edge-based scheme may not be able to undertake all data detection tasks due to limited computing resources of edge devices.Therefore,we propose a cloud-edge collaborative smart grid fault detection system,next to which edge devices are placed,and equipped with a lightweight neural network with different precision for fault detection.In addition,a sub-optimal and realtime communication and computing resource allocation method is proposed based on deep reinforcement learning.This method greatly speeds up solution time,which can meet the requirements of data transmission delay,maximize the system throughput,and improve communication efficiency.Simulation results show the scheme is superior in transmission delay and improves real-time performance of the smart grid detection system.

ANALYSIS AND DESIGN OF FAULT-TOLERANT CAPABILITY OF SINGLE-STAGE INTERCONNECTION NETWORK RMISE

The fault tolerance (FT) parameter K and the communication delay (CD) parameter dof a famous interconnection network called ISE has been studied in detail in this paper.A new network named RMISE has been designed, which has certain FT capability (K=2)and the minimum CD order (d = 0(log_2n)). Different routing algorithms have also beengiven to find the communication path between any pair of processor units in faultfreeand fault conditions.

A Kind of Multistage Interconnection Networks with Multiple Paths

Multistage Interconnection Networks (MINs) are often used to provide interconnections in multiprocessor systems. A unique path MIN usually has lower hardware complekity and a simple control algorithm, but it lacks fault tolerance.This paper proposes a kind of multipath MINs, which are obtained by adding auxiliary links at the final stage in Quad nee (QT) networks so that they canprovide more paths between each source-destination pair, and presents theirrouting algorithm which is both destination tag based and adaptive. Starting with the routing tag for the minimum path between a given source-destinationpair, the routing algorithm uses a set of rules to select switches and modifyrouting tag. In addition to trying the andliary link when linko and link1 areunavailable, link1 will be tried when link0 is unavailable. This feattire dis-tinguishing the proposed routing algorithm from that for QT networks makesbetter use of all the possible paths between the given source-destination pair.In the end, this paper introduces a performance index, which is called capacity,to compare different kinds of MINs. Comparison shows that the proposed MINshave better capacity than QT networks.