Fault Tolerance Features Research Articles

Cross-Layer Dual Modular Redundancy Hardened Scheme of Flip-Flop Design Based on Sense-Amplifier

As the demand for low-power and high-speed logic circuits increases, the design of differential flip-flops based on sense-amplifier (SAFF), which have excellent power and speed characteristics, has become more and more popular. Conventional SAFF (Con SAFF) and improved SAFF designs focus more on the improvement of speed and power consumption, but ignore their Single-Event-Upset (SEU) sensitivity. In fact, SAFF is more susceptible to particle impacts due to the small voltage swing required for differential input in the master stage. Based on the SEU vulnerability of SAFF, this paper proposes a novel scheme, namely cross-layer Dual Modular Redundancy (DMR), to improve the robustness of SAFF. That is, unit-level DMR technology is performed in the master stage, while transistor-level stacking technology is used in the slave stage. This scheme can be applied to some current typical SAFF designs, such as Con SAFF, Strollo SAFF, Ahmadi SAFF, Jeong SAFF, etc. Detailed HSPICE simulation results demonstrate that hardened SAFF designs can not only fully tolerate the Single Node Upset of sensitive nodes, but also partially tolerate the Double Node Upset caused by charge sharing. Besides, compared with the conventional DMR hardened scheme, the proposed cross-layer DMR hardened scheme not only has the same fault-tolerant characteristics, but also greatly reduces the delay, area and power consumption.

Assessment of a Nine-Phase Induction Motor Drive for Metal Industry Applications

Metal industries combine several conditions that match with the advantages of multiphase motor drives, such as high power and high reliability. High power usually means cumbersome multilevel converters, with very expensive high-blocking voltage semiconductors. By adding more phases, it is possible to reduce the motor drive voltage levels and to use two-level converters with more common and less expensive low-blocking voltage power modules. High reliability means lower probability of unexpected production interruption, which is achieved by the fault-tolerant characteristic of the multiphase motor drive. In this article, a wire rod plant is depicted and the replacement of a traditional three-phase motor drive by a nine-phase one is discussed. Experimental results showing the effects of faults in multiphase drive on torque and current waveforms are presented, including their mitigation by the use of a post fault control method. This article also includes reliability calculations for the nine-phase motor drive in order to compare its lifetime with that of the three-phase conventional alternative.

Sensor/actuator fault tolerant sliding mode control for anti-lock braking in a quarter electric vehicle

This paper proposes a scheme to improve regenerative ABS technology that already exists today by adding accommodation faults to the control system. The nominal control algorithm used is a sliding mode control so that system nonlinearities can be handled properly. The proposed method then is called sensor/actuator fault tolerant sliding mode control system. In designing the proposed control, there are two stages, namely estimation of faults, as well as the active mechanism for reconfiguring controls. Estimation of faults is done by using proportional-integral (PI) observers based on extended state space equation. Whereas the control signal reconfiguration is done actively by replacing measured output with their estimates and compensating for control signal using the actuator fault estimate. The simulation shows that the control system based on the proposed algorithm produces better dynamic performance than the sliding mode control (SMC) without fault tolerant feature. Furthermore, the system provides inherent characteristic for dealing with a minor fault in the hydraulic actuator.

SMOaaS: a Scalable Matrix Operation as a Service model in Cloud

Matrix operations are fundamental to a wide range of scientific applications such as Graph Theory, Linear Equation System, Image Processing, Geometric Optics, and Probability Analysis. As the workload in these applications has increased, the sizes of matrices involved have also significantly increased. Parallel execution of matrix operations in existing cluster-based systems performs effectively for relatively small matrices but significantly suffers as matrices become larger due to limited resources. Cloud Computing offers scalable resources to handle this limitation; however, the benefits of having access to almost-infinite scalable resources in the Cloud also come with challenges of ensuring time and resource-efficient matrix operations. To the best of our knowledge, there is no specific Cloud service that optimizes the efficiency of matrix operations on Cloud infrastructure. To address this gap and offer convenient service of matrix operations, the paper proposes a novel scalable service framework called Scalable Matrix Operation as a Service. Our framework uses Dynamic Matrix Partition techniques, based on matrix operation and sizes, to achieve efficient work distribution, and scales based on demand to achieve time and resource-efficient operations. The framework also embraces the basic features of security, fault tolerance, and reliability. Experimental results show that the adopted dynamic partitioning technique ensures faster and better performance when compared to the existing static partitioning technique.

Modeling, Control and Power Management of Six-Phase PMSM Based Shipboard MVDC Distribution System

In the modern shipboard power system, there is a growing concern about reduced fuel economy, efficiency improvement, and minimized emission in recent years. Besides, considering the islanded nature of the shipboard power system, ensuring the system reliability at both generation and load side is crucial. In this context, a hybrid medium voltage DC (MVDC) distribution system concept with diesel engine, PV system, and battery energy storage system (BESS) as the generators for the shipboard power system is proposed. Variable speed operation of a diesel engine is considered for the benefit of minimal specific fuel oil consumption (SFOC). Regarding the fault-tolerant characteristics of six-phase permanent magnet synchronous machine (PMSM), it is used for both generating and motoring application, thus maintaining system reliability at any time. A hierarchical control system is designed and implemented to ensure proper load power-sharing among the generators and to regulate the dc-link voltage of the proposed MVDC distribution system. To bolster the intent of minimal SFOC zone operation of diesel engines and coordination between the generators and load, a deterministic rule-based power management system is proposed and implemented. The simulation is carried out for potential operational modes of a cruise ship in the MATLAB/Simulink environment. Simulation results show that the proposed topological and control structure has satisfactory performance in terms of power delivery, stable dc-link dynamics, and overall system stability.

A Fault Tolerant Scheme for Integration of Remote Renewable Energy Sources With HVDC System

The paper presents a fault tolerant scheme for integrating renewable energy sources to HVDC system using a new modular resonant DC-DC converter. The proposed DC-DC converter consists of many identical low voltage submodules which consist of two controllable switches, one diode and a capacitor. The switches of the proposed DC-DC converter are configured to provide the converter an inherent fault tolerant feature which enables it to isolate itself during DC faults in the HVDC system. Zero current switching (ZCS) is also achieved for all the switches used in the converter. The paper focusses on the integration of renewable energy sources to HVDC transmission system using the proposed tapping scheme. The performance of the proposed scheme to evacuate power from renewable energy sources to HVDC transmission system has been demonstrated using simulation studies done in PSCAD/EMTDC. The performance of the proposed DC-DC converter is also verified with experimental results.

Internet-of-Things-Assisted Smart System 4.0 Framework Using Simulated Routing Procedures

The environment and energy are two important issues in the current century. The development of modern society is closely linked to energy and the environment. Internet of Things (IoT) and Wireless Sensor Networks (WSNs) have recently been developed substantially to contribute to the fourth transformation of the power grid, namely the smart grid. WSNs have the potential to improve power grid reliability via cable replacements, fault-tolerance features, large-scale protection, versatility to deploy, and cost savings in the smart grid environment. Moreover, because of equipment noise, dust heat, electromagnetic interference, multipath effects, and fading, current WSNs are making it very difficult to provide effective communication for the smart grid (SG) environment, in which WSN work is more difficult. For the smart system 4.0 framework, a highly reliable communication network based on the WSN is critically important for the successful operation of electricity grids in the next decade. To solve the above problem, a Robust Bio-Dynamic Stimulated Routing Procedure (RDSRP) has been proposed based on the real-time behavior of a new Hybrid Bird Optimizer (HBO) model. The presented innovative research and development is a small yet important aspect of continuous critical activities that address one of our society’s major challenges and that reverse the dangerous trends of environmental destruction. This study explores some of the most recent advances in this area, including energy efficiency and energy harvesting, which are expected to have a significant impact on green topics under smart systems in the Internet of things. The experimental results show that the proposed distributed system suggestively enhances network efficiency and reduces the transmission of excess packets for wireless sensor network-based smart grid applications.

Algorithm for Clustering the Moduli of RNS for the Application of Optimization of Time Complexity in Standard Cipher System

Residue number system (RNS) has emerged as a knocking field of research due to its high speed, fault tolerant, carry free and parallel characteristics. Due to these features it has got important role in high performance computing especially with reduced delay. There are various algorithms have been found as a result of the research with respect to RNS. Additionally, since RNS reduces word length due to the modular operations, its computations are faster compared to binary computations. But the major challenges are the selection of moduli sets for the forward (decimal to residue numbers) and reverse (residue numbers to decimal) conversion. RNS performance is purely depending on how efficiently an algorithm computes / chooses the moduli sets [1]-[6]. This paper proposes new method for selecting the moduli sets and its usage in cryptographic applications based on Schonhage modular factorization. The paper proposes six moduli sets {6qk1, 6qk+1, 6qk+3, 6qk+5, 6qk+7, 6qk+11} for the RNS conversions but the Schonhage moduli sets are expressed as the exponents that creates a large gap between the moduli’s computed. Hence, a new method is proposed to for computing moduli sets that helps in representing all the decomposed values approximately in the same range.

A Fault-Tolerant Multilevel Inverter Topology With Preserved Output Power and Voltage Levels Under Pre- and Postfault Operation

Low reliability is one of the significant worries of a multilevel inverter (MLI) and which results due to the presence of a higher number of switches and capacitors as compared with the conventional two-level inverter. Consequently, the fault-tolerant (FT) operation of MLI has attracted significant research attention. Therefore, in this article, a nine-level inverter topology with FT characteristics is discussed. The proposed topology is capable of tolerating short-circuit and open-circuit faults not only in the single switch but also in multiple switches. It preserves output power, voltage levels, and capacitor voltage balancing under pre- and postfault operation. The proposed MLI topology requires the least number of dc sources, capacitors, switches, clamping diodes, and total blocking voltage in comparison to recently proposed topologies. Thus, offering better efficiency profile under pre- and postfault conditions. The proposed work has been validated experimentally with a laboratory prototype.

Single and multiple switch fault‐tolerance capabilities in a hybrid five‐level inverter topology

The redundancy in switching states to generate different voltage levels is of great importance to incorporate fault-tolerant features in multilevel inverters. However, this redundancy comes at the expense of high device count, which is paralleled with vulnerable characteristics of semiconductor devices, resulting in low reliability. About this concern, the present study introduces a novel fault-tolerant topology to generate the five-level output voltage. The proposed topology can tolerate open-circuit failure, for single and multiple switches with the help of novel redundant leg architecture and short-circuit condition is dealt with the fast fuses. The comparative study with recent literature is discussed, which reveals the superiority of the proposed topology, in terms of qualitative as well as quantitative parameters. Switching strategies are proposed under different single and multiple switch fault cases, which achieves self-balancing of capacitor voltage. Thus, no complex control scheme is required. The simulation is performed in MATLAB/Simulink, and the feasibility of the proposed topology is validated using experimental results.

U-Model-Based Sliding Mode Controller Design for Quadrotor UAV Control Systems

This paper proposes a U-model-based fault-tolerant controller design method in order to ensure the unmanned aerial vehicle (UAV) flight performance when subject to the actuator failures. Depending on the decoupled quadrotor model, this paper presents a sliding mode control method based on U-model in detail and realizes fault-tolerant control for the quadrotor UAV with the stability theory and simulation experiment verifications. The results show that the new controller designed by using the U-model method can simplify the controller design process which has good fault-tolerant characteristics when actuator faults occur compared with the traditional method.

Designing a decentralized fault-tolerant software framework for smart grids and its applications

Abstract The vision of the ‘Smart Grid’ anticipates a distributed real-time embedded system that implements various monitoring and control functions. As the reliability of the power grid is critical to modern society, the software supporting the grid must support fault tolerance and resilience of the resulting cyber-physical system. This paper describes the fault-tolerance features of a software framework called Resilient Information Architecture Platform for Smart Grid (RIAPS). The framework supports various mechanisms for fault detection and mitigation and works in concert with the applications that implement the grid-specific functions. The paper discusses the design philosophy for and the implementation of the fault tolerance features and presents an application example to show how it can be used to build highly resilient systems.

Two-Stage Kalman Filter for Fault Tolerant Estimation of Wind Speed and UAV Flight Parameters

Abstract In this study, an estimation algorithm based on a two-stage Kalman filter (TSKF) was developed for wind speed and Unmanned Aerial Vehicle (UAV) motion parameters. In the first stage, the wind speed estimation algorithm is used with the help of the Global Positioning System (GPS) and dynamic pressure measurements. Extended Kalman Filter (EKF) is applied to the system. The state vector is composed of the wind speed components and the pitot scale factor. In the second stage, in order to estimate the state parameters of the UAV, GPS, and Inertial Measurement Unit (IMU) measurements are considered in a Linear Kalman filter. The second stage filter uses the first stage EKF estimates of the wind speed values. Between these two stages, a sensor fault detection algorithm is placed. The sensor fault detection algorithm is based on the first stage EKF innovation process. After detecting the fault on the sensor measurements, the state parameters of the UAV are estimated via robust Kalman filter (RKF) against sensor faults. The robust Kalman filter algorithm, which brings the fault tolerance feature to the filter, secures accurate estimation results in case of a faulty measurement without affecting the remaining good estimation characteristics. In simulations, noise increment and bias type of sensor faults are considered.

Fault-tolerant functional reactive programming (extended version)

Abstract Highly critical application domains, like medicine and aerospace, require the use of strict design, implementation, and validation techniques. Functional languages have been used in these domains to develop synchronous dataflow programming languages for reactive systems. Causal stream functions and functional reactive programming (FRP) capture the essence of those languages in a way that is both elegant and robust. To guarantee that critical systems can operate under high stress over long periods of time, these applications require clear specifications of possible faults and hazards, and how they are being handled. Modeling failure is straightforward in functional languages, and many functional reactive abstractions incorporate support for failure or termination. However, handling unknown types of faults, and incorporating fault tolerance into FRP, requires a different construction and remains an open problem. This work demonstrates how to extend an existing functional reactive framework with fault tolerance features. At value level, we tag faulty signals with reliability and probability information and use random testing to inject faults and validate system properties encoded in temporal logic. At type level, we tag components with the kinds of faults they may exhibit and use type-level programming to obtain compile-time guarantees of key aspects of fault tolerance. Our approach is powerful enough to be used in systems with realistic complexity, and flexible enough to be used to guide system analysis and design, validate system properties in the presence of faults, perform runtime monitoring, and study the effects of different fault tolerance mechanisms.

A Behavior-Driven Coordination Control Framework for Target Hunting by UUV Intelligent Swarm

One of most primitive problems by unmanned underwater vehicle intelligent swarm (UIS) is coordination control, which has a great significance for realization of target hunting with great performance of efficiency and robustness. Existing studies concentrate on behavior-based centralized or distributed control approaches with the prior knowledge and mostly do not elaborately consider behavior conflicts and constraint differences. Therefore, a novel behavior-driven coordination control framework including topology architecture and swarm control which is inspired by immune mechanism, is investigated for target hunting of heterogeneous UIS under unknown and uncertain environment in this paper. For topology architecture, a hybrid non-central distributed topology is developed as a novel immune-inspired architecture to regulate agents with self-organizational and fault-tolerance features. For swarm control, a dual-layer switching control scheme composed by global control and local control, is proposed to drive behaviors via behavioral-intensity, the trigger of switching is when the target is detected. The global control approach is employed to search target, in which two constraints of energy consumption and healthy-state are considered to achieve good operational reliability. While the local control approach is developed to form the dynamic alliance of tracking and capturing, in which behavioral-intensity control strategy for behavior aggregation and decision-making control strategy for behavior selection are respectively designed to avoid behavior conflicts. Simulation results demonstrate that proposed framework can accomplish hunting under various situations such as hunter agent is random or fixed distribution, and the number of targets asynchronously appears. It is confirmed that our framework is capable of achieving the target hunting under unknown and uncertain environment with greater efficiency and robustness.

MACE camera controller embedded software: Redesign for robustness and maintainability

Abstract Control and monitoring software for data acquisition systems should have an efficient, reliable, and robust design comprising dual redundant communications, fault tolerant behavior, error handling, and recovery features as well as simple deployment and maintainability. The Major Atmospheric Cherenkov Experiment (MACE) telescope comprises many functionally diverse subsystems. The camera is one of its major subsystems and it is responsible for imaging and event data acquisition. The central camera controller (CCC) manages and coordinates all the actions of the camera subsystems and it collects monitoring data for the MACE operator console. The robustness, efficiency, and reliability of the CCC are vital for conducting successful observations. Prototype software was developed to control the basic functions of the system and the complexity of the software increased as the system evolved over time due to the addition of functionalities. The remote location of the telescope also imposes some constraints on achieving the maximum reachability. Thus, the CCC software was redesigned from scratch to overcome the existing issues and to satisfy the system constraints. The improvement in the overall performance of the system as a result of new design of the software is described in this study. The most important design aspects of the new software are described along with its requirements and advantages.

Assessment of a Universal Reconfiguration-less Control Approach in Open-Phase Fault Operation for Multiphase Drives

Multiphase drives have been important in particular industry applications where reliability is a desired goal. The main reason for this is their inherent fault tolerance. Different nonlinear controllers that do not include modulation stages, like direct torque control (DTC) or model-based predictive control (MPC), have been used in recent times to govern these complex systems, including mandatory control reconfiguration to guarantee the fault tolerance characteristic. A new reconfiguration-less approach based on virtual voltage vectors (VVs) was recently proposed for MPC, providing a natural healthy and faulty closed-loop regulation of a particular asymmetrical six-phase drive. This work validates the interest in the reconfiguration-less approach for direct controllers and multiphase drives.

Study on dual redundant PMSM drive design and fault-tolerant control strategy

ABSTRACTWith the development and application of servo system, the requirements of high performance servo system are getting higher and higher. Its key is the high-performance motor that has the fault-tolerance to improve the motor reliability. This paper proposes a novel dual redundant PMSM (Permanent magnet synchronous motor), which has multiple same armature winding. Each winding has same three phases and is controlled by inverter module. Based on the fault-tolerant control system model, a reliable fault-tolerant control strategy has been proposed. The experiment platform is built to carry out consistency experiment of each redundancy, response characteristic experiment and fault-tolerant experiment of two redundancies in the PMSM. The experiment result shows the dual redundant PMSM has a good response and fault-tolerance characteristics.

Practical task allocation for software fault-tolerance and its implementation in embedded automotive systems

Due to the advent of active safety features and automated driving capabilities, the complexity of embedded computing systems within automobiles continues to increase. Such advanced driver assistance systems (ADAS) are inherently safety-critical and must tolerate failures in any subsystem. However, fault-tolerance in safety-critical systems has been traditionally supported by hardware replication, which is prohibitively expensive in terms of cost, weight, and size for the automotive market. Recent work has studied the use of software-based fault-tolerance techniques that utilize task-level hot and cold standbys to tolerate fail-stop processor and task failures. The benefit of using standbys is maximal when a task and any of its standbys obey the placement constraint of not being co-located on the same processor. We propose a new heuristic based on a “tiered” placement constraint, and show that our heuristic produces a better task assignment that saves at least one processor up to 40% of the time relative to the best known heuristic to date. We then introduce a task allocation algorithm that, for the first time to our knowledge, leverages the run-time attributes of cold standbys. Our empirical study finds that our heuristic uses no more than one additional processor in most cases relative to an optimal allocation that we construct for evaluation purposes using a creative technique. We also extend our heuristic to support mixed-criticality systems which allow for overload operation. We have designed and implemented our software fault-tolerance framework in AUTOSAR, an automotive industry standard. We use this implementation to provide an experimental evaluation of our task-level fault-tolerance features. Finally, we present an analysis of the worst-case behavior of our task recovery features.

Analysis of torque ripple and fault-tolerant capability for a 16/10 segmented switched reluctance motor in HEV applications

PurposeThe torque ripple and fault-tolerant capability are the two main problems for the switched reluctance motors (SRMs) in applications. The purpose of this paper, therefore, is to propose a novel 16/10 segmented SRM (SSRM) to reduce the torque ripple and improve the fault-tolerant capability in this work.Design/methodology/approachThe stator of the proposed SSRM is composed of exciting and auxiliary stator poles, while the rotor consists of a series of discrete segments. The fault-tolerant and torque ripple characteristics of the proposed SSRM are studied by the finite element analysis (FEA) method. Meanwhile, the characteristics of the SSRM are compared with those of a conventional SRM with 8/6 stator/rotor poles. Finally, FEA and experimental results are provided to validate the static and dynamic characteristics of the proposed SSRM.FindingsIt is found that the proposed novel 16/10 SSRM for the application in the belt-driven starter generator (BSG) possesses these functions: less mutual inductance and high fault-tolerant capability. It is also found that the proposed SSRM provides lower torque ripple and higher output torque. Finally, the experimental results validate that the proposed SSRM runs with lower torque ripple, better output torque and fault-tolerant characteristics, making it an ideal candidate for the BSG and similar systems.Originality/valueThis paper presents the analysis of torque ripple and fault-tolerant capability for a 16/10 segmented switched reluctance motor in hybrid electric vehicles. Using FEA simulation and building a test bench to verify the proposed SSRM’s superiority in both torque ripple and fault-tolerant capability.