Fault-tolerant Design Research Articles

2-Odd Labeling of Graphs Using Certain Number Theoretic Concepts and Graph Operations

Graph theory plays a significant role in a variety of real-world systems. Graph concepts such as labeling and coloring are used to depict a variety of processes and relationships in material, social, biological, physical, and information systems. Specifically, graph labeling is used in communication network addressing, fault-tolerant system design, automatic channel allocation, etc. 2-odd labeling assigns distinct integers to the nodes of <img src=image/13427595_01.png> in such a manner, that the positive difference of adjacent nodes is either 2 or an odd integer, <img src=image/13427595_02.png>, <img src=image/13427595_03.png>. So, <img src=image/13427595_04.png> is a 2-odd graph if and only if it permits 2-odd labeling. Studying certain important modifications through various graph operations on a given graph is interesting and challenging. These operations mainly modify the underlying graph's structure, so understanding the complex operations that can be done over a graph or a set of graphs is inevitable. The motivation behind the development of this article is to apply the concept of 2-odd labeling on graphs generated by using various graph operations. Further, certain results on 2-odd labeling are also derived using some well-known number theoretic concepts such as the Twin prime conjecture and Goldbach's conjecture, besides recalling a few interesting applications of graph labeling and graph coloring.

Fault-Tolerant Control of a Dual-Stator PMSM for the Full-Electric Propulsion of a Lightweight Fixed-Wing UAV

The reliability enhancement of electrical machines is one of the key enabling factors for spreading the full-electric propulsion to next-generation long-endurance UAVs. This paper deals with the fault-tolerant control design of a Full-Electric Propulsion System (FEPS) for a lightweight fixed-wing UAV, in which a dual-stator Permanent Magnet Synchronous Machine (PMSM) drives a twin-blade fixed-pitch propeller. The FEPS is designed to operate with both stators delivering power (active/active status) during climb, to maximize performances, while only one stator is used (active/stand-by status) in cruise and landing, to enhance reliability. To assess the fault-tolerant capabilities of the system, as well as to evaluate the impacts of its failure transients on the UAV performances, a detailed model of the FEPS (including three-phase electrical systems, digital regulators, drivetrain compliance and propeller loads) is integrated with the model of the UAV longitudinal dynamics, and the system response is characterized by injecting a phase-to-ground fault in the motor during different flight manoeuvres. The results show that, even after a stator failure, the fault-tolerant control permits the UAV to hold altitude and speed during cruise, to keep on climbing (even with reduced performances), and to safely manage the flight termination (requiring to stop and align the propeller blades with the UAV wing), by avoiding potentially dangerous torque ripples and structural vibrations.

Algorithms and Methods for the Fault-Tolerant Design of an Automated Guided Vehicle.

Researchers around the globe have contributed for many years to the research field of fault-tolerant control; the importance of this field is ever increasing as a consequence of the rising complexity of technical systems, the enlarging importance of electronics and software as well as the widening share of interconnected and cloud solutions. This field was supplemented in recent years by fault-tolerant design. Two main goals of fault-tolerant design can be distinguished. The first main goal is the improvement of the controllability and diagnosability of technical systems through intelligent design. The second goal is the enhancement of the fault-tolerance of technical systems by means of inherently fault-tolerant design characteristics. Inherently fault-tolerant design characteristics are, for instance, redundancy or over-actuation. This paper describes algorithms, methods and tools of fault-tolerant design and an application of the concept to an automated guided vehicle (AGV). This application took place on different levels ranging from conscious requirements management to redundant elements, which were consciously chosen, on the most concrete level of a technical system, i.e., the product geometry. The main scientific contribution of the paper is a methodical framework for fault-tolerant design, as well as certain algorithms and methods within this framework. The underlying motivation is to support engineers in design and control trough product development process transparency and appropriate algorithms and methods.

Performance modeling for condition-based activation of the redundant safety system subject to harmful tests

Redundancy is a widely adopted measure for the enhancement of safety system performance. This fault-tolerance design can keep the system functioning through one unit if the other has failed. Besides the continuous aging degradation, mechanical units expose to random shocks, resulting in the dependence. In practice, it is often sufficient to activate only one unit in case of a shock so that the degradation will then be intensified. Unit-level failure occurs when the total degradation level reaches a certain level and will keep hidden. Thus, periodic tests are arranged to reveal the system state, accompanying the side effects on the existing degradation given the test-induced additional stress. A novel condition-based activation policy is proposed based on the system state, referring to how to preset the allocation of units to withstand potential shocks in the upcoming test interval. In this paper, analytical formulas are developed to evaluate system performance with the involvement of these aforementioned factors. Finally, numerical examples are presented to find an optimal test and activation policy to reach minimum system unavailability in a given service time horizon. This study is expected to provide clues for practitioners in the optimal test and operation of redundant structure.

Study on New Prefabricated Reinforced Concrete Structure Technology Based on Fault-Tolerant Design

To reduce the impact of poor field connection on structural safety in prefabricated concrete structures, a new kind of prefabricated reinforced concrete structure—an FTPC (fault-tolerant prefabricated concrete) structure based on the fault-tolerant design concept—was proposed and studied in this paper. The horizontal load-bearing units of an FTPC structure are fully prefabricated or semi-prefabricated slabs. The vertical load-bearing units are formed by four types of prefabricated cantilever components. Prefabricated cantilever components are horizontally connected by welded connection and vertically connected by a specific connection method using steel tubes and cast-in-place concrete. A mathematical sampling method can be used to select several welded connection nodes as disconnected nodes to consider the actual weld quality. Enveloping design can be carried out to obtain the final design results of each cantilever component, which can realize the fault-tolerant design and better ensure the structure safety. Finite element analysis was carried out for a two-story villa as an example to verify the feasibility and rationality of an FTPC structure. Study results show that an FTPC structure can meet the requirements of safety and applicability. Moreover, it has the advantages of a flexible arrangement of load-bearing components, a clear force transmission mechanism, and a moderate component volume.

Backstepping sliding mode fault-tolerant control for the wind turbine system with disturbance observer

To guarantee the safe and stable operation of wind farms, this article establishes a backstepping sliding mode fault-tolerant controller for the wind turbine system to surmount uncertain problems, including actuator gain–bias faults, system modeling errors, and external stochastic disturbances. The nonlinear disturbance observer is employed for the stochastic disturbances, which can online estimate and compensate the external disturbance term. In addition, the backstepping control strategy is introduced to reduce the complexity of fault-tolerant controller design. Subsequently, combining the backstepping control algorithm and nonlinear disturbance observer, a disturbance observer-based backstepping sliding mode fault-tolerant control approach is applied for the wind turbine system. Thereinto, the terminal attractor is employed, which is mainly utilized to improve the convergence rate of the sliding surface and reduce the chattering phenomenon. The stability of the wind power closed-loop control system is rigorously verified via Lyapunov stability theory, which can obtain satisfactory control performance. Finally, numerical simulation results demonstrate that the proposed control approach can guarantee that the system state quickly reaches stability within 6–8 s, and the steady-state adjustment time is greatly reduced to 50%–62% when compared with the proportional–integral–derivative control and sliding mode control.

Quantum dot Cellular Automata based Fault Tolerant Fingerprint Authentication Systems using Reversible Logic Gates

The limits and difficulties looked by CMOS innovation in the nano system has prompted the exploration of other potential advancements which can work with same functionalities anyway with lower power scattering and higher speed. One such technology is Quantum dot Cellular Automata (QCA). In this paper, QCA is explored to design the authentication system. This paper first presents the basic operating principle of a Fingerprint Authentication System (FAS) followed by fault tolerance analysis of four efficient XOR gate designs in the literature. The XOR gate is then used in the proposed four fault tolerant designs of reversible FAS in QCA, which are based on different reversible gates. Based on the evaluation of different performance parameters, it is seen that the proposed FAS designs are cost efficient and achieve improvement up to 59.46% in terms of number of cells, 67.16% improvement in cell area, 67.14% improvement in total area, 66.67% improvement in latency and 90.51% improvement in terms of circuit cost from the existing design Furthermore, the energy dissipation examination of the proposed designs is also additionally introduced. Subsequently, the proposed designs can be effectively used in biometric applications demanding ultra-low power consumption, higher operating speed and minimal area utilization.

Reconfiguration Control Design of UAV against Actuator Faults Based on Control Allocation Method

The paper concentrates on the problem of fault-tolerant control of UAV against actuator faults from the perspective of flight control system architecture. Using backstepping control method and inverse optimization theory, the design of backstepping optimal control law was constructed. Based on the fault monitoring mechanism of vehicle management computer in the distributed flight control and control allocation system, a fault-tolerant control design method was established in the case of multiple failure modes of the actuators, which compensates the influence caused by the failures. Finally, the effectiveness of the proposed strategy was verified by numerical simulation.

Energy aware fault tolerant clustering with routing protocol for improved survivability in wireless sensor networks

Wireless Sensor Networks (WSN) remain a hot research topic due to its wide range of application areas like environmental monitoring, military surveillance, healthcare, and disaster management. Network survivability is one of the challenging issues in WSN that needs to be maximized for long-run operation of the network. It can be proficiently improved by effective utilization of available energy since the nodes in WSN operate only via in-built batteries. The studies conducted earlier have mainly focused on the design of clustering and routing protocols to reduce energy consumption in the network. With this motivation, the current research paper presents a novel Energy-Aware Fault Tolerant Clustering with Routing for Improved Survivability (EAFTC-RIS) technique in WSN. The proposed EAFTC-RIS technique intends to select the Cluster Heads (CHs) and optimal routes to the destination in an optimal manner with fault tolerant mechanism. The proposed EAFTC-RIS technique primarily designs Moth Flame Optimization (MFO)-based clustering scheme for CH selection and cluster construction. Also, fault tolerant mechanism is considered to further enhance the survivability of the network. In addition, Social Spider Optimization (SSO)-based routing approach is also employed for optimal selection of routes in WSN. Clustering, routing, and fault tolerant mechanism designs, with multiple input variables, result in enhanced network survivability. The proposed EAFTC-RIS technique was validated for its performance and the outcomes were inspected under various aspects. The simulation outcomes demonstrate the superiority of EAFTC-RIS technique over recent approaches namely, EAFTC-RIS, FUCCAR-GWSO, FBECS, MLSLEEP, and Bee Cluster.

Process-Resilient Fault-Tolerant Delay-Locked Loop Using TMR With Dynamic Timing Correction

A delay-locked loop (DLL) circuit is often useful for the clock synchronization in a chip incorporating multiple functional dies. In this work, we present a process-resilient fault-tolerant DLL design. We will first show that a na&#x00EF;ve triple-module redundancy (TMR) technique cannot work well unless with a simple yet powerful static timing correction scheme to nullify the adversary effect caused by the voter circuit&#x2019;s delay. Furthermore, we enhance it with a dynamic scheme so that the overall performance is immune to process variation. Through the proposed schemes, the maximum phase error over 1000 clock cycles between the DLL&#x2019;s input and output clock signals after locking, which is often considered as the most important performance metric, can be reduced tremendously from 130 ps using only na&#x00EF;ve TMR to 20 ps using static timing correction, and then further down to 11 ps using the dynamic timing correction.

Rigorous Design of Fault Tolerance and Recovery Algorithm for Disaster Management and Relief Distribution System using Event-B

India is vulnerable to disasters such as earthquakes, floods, tsunamis, landslides forest fires and cyclones due to its unique socio-economic and geo-climatic conditions. Twenty seven out of thirty-six states and union territories are prone to different types of disasters which cause loss of life, disruption of livelihoods, damage to infrastructure and property which in turn becomes a heavy burden on the national economy. Effective management of relief work is a key step towards normalizing human life post disaster. In this paper, we have presented the formal development and verification of a fault tolerance and recovery algorithm for district level disaster control centers in India which are connected to each other via a communication network. Formal methods help in the verification of critical properties of complex systems by developing mathematical models so that design errors can be detected and removed during the early stages of software development. Event-B, which is a formal method and Rodin platform is used for this work. Event-B is a mathematical language of first-order logic to provide a solution to the complex algorithms formally. In this algorithm a Disaster Control Centre is chosen as the coordinator based on its unique vote value. This vote value is allotted and modified dynamically based on the extent of damage in the area where the center is located. The center having the highest vote value among the currently active centers is elected as the coordinator. The correctness of the algorithm is verified through discharge of proof obligations generated by the Event-B model.

A two‐dimensional RC network topology for fault‐tolerant design of analog circuits

This paper proposes a novel one-port passive circuit topology consisting of a two-dimensional network of resistors and capacitors, which can be used as a fault-tolerant building block for analog circuit design. Through an analytical procedure, the network is shown to follow simple first-order admittance dynamics. A Monte Carlo method is employed to describe the effect of simultaneous faults (short or open circuit) in random network elements in terms of confidence bounds in the frequency-domain admittance profile. Faults in 10% of the elements resulted in only minor changes of the frequency response (up to 3.9 dB in magnitude and 12.5 ∘ in phase in 95% of the cases). An example is presented to illustrate the use of the proposed RC network in the fault-tolerant design of a low-pass filter.

Fuzzy multi-objective fault-tolerant control for nonlinear Markov jump singularly perturbed systems with persistent dwell-time switched transition probabilities

This paper studies the discrete-time slow state feedback fault-tolerant controller design issue for Takagi-Sugeno fuzzy-model-based Markov jump singularly perturbed nonlinear systems, in which transition probabilities of systems subject to persistent dwell-time switching mechanism. In order to eliminate the influence of actuator faults and provide a more flexible control strategy, a multi-objective fault-tolerant controller is designed to ensure the stability of the system and meet the requirements of various performance indexes. The goal is to establish some sufficient conditions, which ensure the mean-square exponential stability and the extended dissipativity performance of the closed-loop system. Furthermore, the gains of the designed controller can be obtained by solving the problem of convex optimization. Finally, the availability of the designed controller is demonstrated by a numerical example and a tunnel diode circuit system.

A Low-cost Fault Tolerance Method for ARM and RISC-V Microprocessor-based Systems using Temporal Redundancy and Approximate Computing through Simplified Iterations

Approximate Computing techniques have been successfully used to reduce the overhead associated with redundancy in fault-tolerant system designs. This paper presents a fault tolerance method to reduce the execution time overhead of the well-known Time Redundancy technique by means of an improvement proposed for the Approximate Computing software-based technique known as loop perforation. Time Redundancy is a software-based fault tolerance technique that involves executing replicas of a task at different times. We propose to approximate the tasks to be executed using a new approximate computing technique based on loop perforation, i.e., simplified iterations. The novelty of this method is the combined use of the fault tolerance technique, temporal redundancy, jointly with the new proposed Approximate Computing technique, simplified iterations. The proposal is validated through simulation-based fault injection campaigns on several test programs for the ARM and RISC-V microprocessor architectures. Experimental results verified not only the applicability of the proposal in different architectures, but also its effectiveness, showing a good trade-off between reliability, error and overhead. Results showed that using the proposed method, a normalized mean work to failure (MWTF) up to 5.28× was obtained with approximation errors lower than those obtained using the traditional loop perforation technique.

Fault-Tolerant System Design for Doubly Salient Electromagnetic Machine Under Loss of Excitation

Aiming at the problem that the traditional doubly salient electromagnetic machine (DSEM) cannot work when the excitation loss occurs, this article designs and analyzes a fault-tolerant DSEM for excitation loss, and the torque ripple suppression strategy under the fault-tolerant operation is studied. First, the characteristics of the output torque of DSEM before and after excitation-loss is analyzed, and a DSEM with a novel winding configuration is proposed to improve the fault tolerance. Second, under normal/excitation-loss conditions, the structure parameters of the fault-tolerant DSEM are analyzed to reveal the influence of the motor structure on its performance. Then, the steady-state torque of the fault-tolerant DSEM is compared with the traditional DSEM and the switched reluctance motor with the same size, which proves the effectiveness of the fault-tolerant design. By analyzing the inductance and torque characteristics, a torque ripple suppression strategy is proposed for the fault-tolerant DSEM without increasing the complexity of the system. Finally, a prototype is developed, and the experimental results verify the fault-tolerant capability of the prototype and the effectiveness of the proposed torque ripple suppression strategy. The research results of this article provide a specific implementation method for the fault-tolerant system design of DSEM under excitation loss.

A Defect Tolerant Design for 5-Input Majority Gate in Quantum-dot Cellular Automata

A Defect Tolerant Design for 5-Input Majority Gate in Quantum-dot Cellular Automata

A Distributed Fault Diagnosis and Cooperative Fault-Tolerant Control Design Framework for Distributed Interconnected Systems

This paper investigates a design framework for a class of distributed interconnected systems, where a fault diagnosis scheme and a cooperative fault-tolerant control scheme are included. First of all, fault detection observers are designed for the interconnected subsystems, and the detection results will be spread to all subsystems in the form of a broadcast. Then, to locate the faulty subsystem accurately, fault isolation observers are further designed for the alarming subsystems in turn with the aid of an adaptive fault estimation technique. Based on this, the fault estimation information is used to compensate for the residuals, and then isolation decision logic is conducted. Moreover, the cooperative fault-tolerant control unit, where state feedback and cooperative compensation are both utilized, is introduced to ensure the stability of the whole system. Finally, the simulation of intelligent unmanned vehicle platooning is adopted to demonstrate the applicability and effectiveness of the proposed design framework.

An Efficient Algorithm for Mapping Deep Learning Applications on the NoC Architecture

Network-on-chip (NoC) is replacing the existing on-chip communication mechanism in the latest, very-large-scale integration (VLSI) systems because of their fault tolerant design. However, in addition to the design challenges, NoC systems require a mechanism for proper application mapping in order to produce maximum benefits in terms of application-level latency, platform energy consumption, and system throughput. Similarly, the neural-network (NN)-based artificial intelligence (AI) techniques for deep learning are gaining particular interest. These applications can be executed on a cloud-based system, but some of these applications have to be executed on private cloud to integrate the data privacy. Furthermore, the public cloud systems can also be made from these NoC platforms to have better application performance. Therefore, there is a need to optimally map these applications on existing NoC-based architectures. If the application is not properly mapped, then it can create a performance hazard that may lead to delay in calculations, increase in energy consumption, and decrease in the platform lifetime. Hence, the real-time applications requiring AI services can implement these algorithms in NoC-based architectures with better real-time performance. In this article, we propose a multilevel mapping of deep learning AI applications on the NoC architectures and show its results for the energy consumption, task distribution profile, latency, and throughput. The simulation is conducted using the OCTAVE, and the simulation results show that the performance of the proposed mapping technique is better than the direct mapping techniques.

Fault-tolerant adaptive fractional controller design for incommensurate fractional-order nonlinear dynamic systems subject to input and output restrictions

In this article, a fault-tolerant adaptive neural network fractional controller has been proposed for a class of uncertain multi-input single-output (MISO) incommensurate fractional-order non-strict nonlinear systems subject to five different types of unknown input nonlinearities, infinite number of actuators failures and arbitrary independent time-varying output constraints. The barrier Lyapunov function (BLF)-based backstepping technique and fractional Lyapunov direct method (FLDM) have been used to design the controller and establish system stability. To tackle the incommensurate derivatives problem, in each step of the backstepping technique, an appropriate Lyapunov function has been selected based on error variables of the considered step and their boundedness has been proved from the last step to the first one. The computational burden is reduced by decreasing the number of adaptive laws. The developed controller satisfies the output constraints and guarantees convergence of the output tracking error to a small neighborhood of the origin and boundedness of all closed-loop signals. Finally, the effectiveness of the designed controller has been demonstrated via simulating three examples.

Global fast terminal sliding mode based radial basis function neural network for accurate fault estimation in nonlinear systems

The problem of quick and accurate fault estimation in nonlinear systems is addressed in this article by combining the technique of radial basis function neural network (RBFNN) and global fast terminal sliding mode control (GFTSMC) concept. A new strategy to update the neural network weights, by using the global fast terminal sliding surface instead of conventional error back propagation method, is introduced to achieve real time, quick and accurate fault estimation which is critical for fault tolerant control system design. The combination of online learning ability of RBFNN, to approximate any nonlinear function, and finite time convergence property of GFTSMC ensures quick detection and accurate estimation of faults in real time. The effectiveness of the proposed strategy is demonstrated through simulations using a nonlinear model of a commercial aircraft and considering a wide range of sensors and actuators faults. The simulation results show that the proposed method is capable of quick and accurate online fault estimation in nonlinear systems and shows improved performance as compared to conventional RBFNN and other techniques existing in literature.