Search Results (797)

This paper proposes a passive fault-tolerant control strategy for a multi-caliper disc elevator brake system subject to unknown external disturbances and multiple actuator faults. Initially, a detailed analysis of the dynamic equations of the actuator in a multi-caliper disc elevator brake system with actuator faults is conducted. Subsequently, a nonsingular terminal sliding mode fault-tolerant control scheme with rapid fixed-time convergence is proposed, where the settling time is independent of the system’s initial state and can be preset through design parameters. The upper bound of the convergence time is derived using Lyapunov theory, ensuring that the faulty elevator brake control system converges within a predetermined fixed time. Ultimately, theoretical analysis and numerical simulation results confirm that the proposed controller can effectively handle the effects of actuator faults, parametric uncertainties, and external disturbances, ensuring satisfactory tracking accuracy. Full article

This paper addresses the bipartite consensus problem of signed directed multi-agent systems (MASs) subject to actuator faults. This problem plays a crucial role in various real-world systems where agents exhibit both cooperative and competitive interactions, such as autonomous vehicle fleets, smart grids, and robotic networks. To address this, unlike most existing works, an intermediate observer is designed using newly introduced intermediate variables, enabling simultaneous estimation of both agent states and faults. Furthermore, a distributed adaptive observer is developed to help followers estimate the leader’s state, overcoming limitations of prior bounded-input assumptions. Finally, simulation results demonstrate the method’s effectiveness, showing that consensus tracking errors converge to zero under under various fault scenarios and input uncertainties. Full article

A fault-tolerant collaborative control strategy for four-wheel-drive electric vehicles is proposed to address hidden safety issues caused by one or more in-wheel motor faults; the basic design scheme is that the control system is divided into two layers of motion tracking and torque distribution, and three systems, including driving, braking, and front-wheel steering are controlled collaboratively for four-wheel torque distribution. In the layer of motion tracking, a vehicle model with two-degree-of-freedom is employed to predict the control reference values of the longitudinal force and additional yaw moment required; four types of sensors, such as wheel speed, acceleration, gyroscope, and steering wheel angle, are used to calculate the actual values. At the torque distribution layer, SSOD and MSCD distribution schemes are designed to cope with two operating conditions, namely sufficient and insufficient output capacity after local hub motor failure, respectively, focusing on the objective function, constraints, and control variables of the MSCD control strategy. Finally, two operating environments, a straight-line track, and a DLC track, are set up to verify the effectiveness of the proposed control method. The results indicate that, compared with traditional methods, the average errors of the center of mass sideslip angle and yaw rate are reduced by at least 12.9% and 5.88%, respectively, in the straight-line track environment. In the DLC track environment, the average errors of the center of mass sideslip angle and yaw rate are reduced by at least 6% and 4.5%, respectively. The proposed fault-tolerant controller ensures that the four-wheel-drive electric vehicle meets the requirements of handling stability and safety under one or more hub motor failure conditions. Full article

This paper presents a two-step robust fault-tolerant controller of incorporating disturbances and actuator faults rejection for a UAV flight control system, which is challenging due to its complex and nonlinear dynamics. First, the main controller, which is designed separately, considers all the design parameters giving the desired closed loop system response. Second, a method to design a standalone disturbance/fault compensator is suggested, which is integrated into the original system to ensure stability. The degraded system stability and performance are compensated by the compensator, which comes into effect only after the disturbance/fault residual error increases to a certain level. The disturbance/fault compensator is designed based on a nonlinear extended state observer (NESO), which cannot only estimate the system’s states but also the unknown disturbances and fault. In the faultless system, only the main controller is active. When an actuator fault/disturbance occurs, the compensator is automatically activated. This controller scheme solves the traditional control conflict between high performance and robustness. It also guarantees the stability of the system in the presence of the disturbances/faults. A civil fixed-wing unmanned aerial vehicle (UAV) that is equipped with a thrust vector control (TVC) with actuator faults and disturbance is chosen for the simulations, and the results prove the efficacy of the new approach. Full article

With the wide application of the gallium nitride (GaN) preparation method based on Metal–Organic Chemical Vapor Deposition (MOCVD), the automation of MOCVD equipment has become a research hotspot. This paper explores the automation scheme of MOCVD reaction chamber cleaning to improve productivity and reduce labor costs. Firstly, this paper establishes the kinematic solution model of a MOCVD cleaning robot and designs the cleaning robot path planning control algorithm. Considering the error between the initial position of the robot end-effector and the desired initial position in practical applications, this paper further designs a fault-tolerant motion planning algorithm for the initial position error. The simulation results show that the method can effectively reduce the initial position error and make it converge exponentially to zero. Finally, this paper builds the robot control system of the cleaning system and verifies the cleaning effect through tests. The test results show that the system can meet the actual use requirements and realize the reaction chamber cleaning automation goal. Full article

The purpose of this paper is to develop formation control strategies for heterogeneous multi-intelligent-agent systems in complex environments, with the goal of enhancing their performance, reliability, and stability. Complex flight conditions, such as navigating narrow gaps in urban high-rise buildings, pose considerable challenges for agent control. To address these challenges, this paper proposes a consensus-based formation strategy that integrates graph theory and multi-consensus algorithms. This approach incorporates time-varying group consistency to strengthen fault tolerance and reduce interference while ensuring obstacle avoidance and formation maintenance in dynamic environments. Through a Lyapunov stability analysis, combined with minimum dwell time constraints and the LaSalle invariance principle, this work proves the convergence of the proposed control scheme under changing network topologies. Simulation results confirm that the proposed strategy significantly improves system performance, mission execution capability, autonomy, synergy, and robustness, thereby enabling agents to successfully maintain formation and avoid obstacles in both homogeneous and heterogeneous clusters in complex environments. Full article

Different locations and types of faults affect the safe and reliable operation of DC microgrids. Therefore, this paper proposes a secondary multiple fault-tolerant control scheme for a DC microgrid based on a sliding mode observer to ensure the voltage is restored to the rated value and realize the proportional current sharing of all sources. Firstly, the secondary control model of the DC microgrid is established, considering the multiple faults of actuators and sensors simultaneously. Secondly, the system model is transformed into two subsystems by bilinear coordinate transformation, and multiple faults decoupling between the sensor and actuator is realized. Then, two sliding mode observers are designed for the two transformed subsystems. The sliding mode variable structure equivalent principle is used to reconstruct the faults at different positions without knowing the fault models in advance, which is convenient for subsequent processing. Then, the fault-tolerant controller based on the sliding mode observer is designed, which uses the reconstructed value to offset the influence of sensor and actuator faults on the DC microgrid and realizes the fault-tolerant control of the DC microgrid. Finally, the effectiveness of the proposed control strategy is verified by experiments. Full article

Multiphase DC/DC power converter architectures have recently been investigated for powering the superconducting electromagnets in the High-Luminosity (HL) upgrade of the Large Hadron Collider (LHC) at CERN, targeting high-performance figures and reliability. In terms of control, a master–slave voltage/current regulation configuration was previously proposed by the authors as an alternative to other well-known cascaded options. In this work, fault-tolerant features (i.e., diagnosis and reconfiguration under open-circuit switch faults) are incorporated into the aforementioned proposal. These features are highly desirable, as physics experiments—which can last for several hours—should not be interrupted in the event of a recoverable fault in the powering system. Simulation and experimental results are provided, demonstrating the correctness of the proposed fault-tolerant scheme. Full article

This paper provides a consolidated discussion and proposes significant measures in improving and advancing the performance of synchronous machines employed in electric traction applications designed for passenger electric vehicles (EVs). The paper quantifies the discussion on improving the power density (kW/kg) and efficiency (%η) of the machine with the commercially available solutions in terms of new design architectures, advanced emerging materials, and adoption of additive manufacturing (AM) technologies. New challenges and opportunities are identified for the optimized machine designs having the potential to meet the global standards while keeping the cost under control. This paper provides an overview of current trends, an introduction to innovative technologies, and changes in existing manufacturing practices to achieve high-performance electrical machines with improved fault tolerance capabilities and reliability. Thereby meeting the standards for the next generation of electric vehicles. Full article

This paper considers a decentralized and autonomous wireless network of low SWaP (size, weight, and power) fixed-wing UAVs (unmanned aerial vehicles) used for remote exploration and monitoring of targets in an inaccessible area lacking communication infrastructure. Here, the UAVs collaborate to find target(s) and use routing protocols to forward the sensed data of target(s) to an aerial base station (BS) in real-time through multihop communication, which can then transmit the data to a control center. However, the unpredictability of target locations and the highly dynamic nature of autonomous, decentralized UAV networks result in frequent route breaks or traffic disruptions. Traditional routing schemes cannot quickly adapt to dynamic UAV networks and can incur large control overhead and delays. In addition, their performance suffers from poor network connectivity in sparse networks with multiple objectives (exploration and monitoring of targets), which results in frequent route unavailability. To address these challenges, we propose two routing schemes: Pipe routing and TC-Pipe routing. Pipe routing is a mobility-, congestion-, and energy-aware scheme that discovers routes to the BS on-demand and proactively switches to alternate high-quality routes within a limited region around the routes (referred to as the “pipe”) when needed. TC-Pipe routing extends this approach by incorporating a decentralized topology control mechanism to help maintain robust connectivity in the pipe region around the routes, resulting in improved route stability and availability. The proposed schemes adopt a novel approach by integrating the topology control with routing protocol and mobility model, and rely only on local information in a distributed manner. Comprehensive evaluations under diverse network and traffic conditions—including UAV density and speed, number of targets, and fault tolerance—show that the proposed schemes improve throughput by reducing flow interruptions and packet drops caused by mobility, congestion, and node failures. At the same time, the impact on coverage performance (measured in terms of coverage and coverage fairness) is minimal, even with multiple targets. Additionally, the performance of both schemes degrades gracefully as the percentage of UAV failures in the network increases. Compared to schemes that use dedicated UAVs as relay nodes to establish a route to the BS when the UAV density is low, Pipe and TC-Pipe routing offer better coverage and connectivity trade-offs, with the TC-Pipe providing the best trade-off. Full article

In high-speed railway signaling systems, the network structure of the Train Control Center and Inter-locking Integrated System (TIS) is highly complex, with a large number of interfaces, numerous redundant channels, and forwarding components such as switches. These factors result in challenges such as insufficient accuracy, low efficiency, and poor real-time performance in terms of network monitoring and fault diagnosis. As the scale of railway yards continues to expand, these issues are becoming increasingly prominent. To address these challenges, this paper proposes a network fault propagation model based on the Fuzzy Broad Learning System (FBLS). By leveraging nonlinear transformations and feature mapping techniques, FBLS can efficiently extract and analyze network fault features, even with a relatively small amount of data. Experimental results show that the FBLS-based diagnostic model achieves higher accuracy and faster response speed in fault identification and propagation path analysis compared to traditional graph theory and fuzzy reasoning methods. Further comparisons with existing methods validate the advantages of FBLS in handling multi-source data, improving noise tolerance, and adapting to large-scale railway yard network systems, demonstrating its broad application prospects in railway signaling systems. Full article

The traditional consensus algorithm based on the Internet of Vehicles (IoV) system has the disadvantages of high latency, low reliability, and weak fault tolerance, and it cannot make real-time adjustments according to the actual environment, making the system vulnerable to malicious control, inefficiency, and poor environmental adaptability. To solve this problem, we propose a gradually accelerating environment adaptive consensus algorithm, AE-PBFT, that can be applied to IoV. It includes a trust management model that achieves gradual acceleration by recording the historical continuous behavior of nodes, thereby improving the efficiency of screening nodes with different intentions, accelerating the consensus process, and reducing latency. At the same time, we introduce a dynamic consensus group division mechanism based on environmental adaptive changes, which can adaptively adjust the number of nodes participating in the consensus process according to the needs of the operating environment, to deal with extreme situations, thereby improving the reliability and fault tolerance of the system. Experiments confirm that the performance of our proposed solution is superior to current solutions in terms of consensus latency and fault tolerance and is more suitable for the operating environment of IoV. Full article

This article proposes a time-synchronized fault-tolerant convergence control method for n-degree-of-freedom robotic manipulators. The main challenge lies in driving the tracking errors of all joints to converge simultaneously, especially in the presence of system faults, external disturbances, and model uncertainties. We introduce a normalized sign function that guarantees the property of ratio persistence for all joints and plays a crucial role in time-synchronized convergence control. A time-synchronized convergence observer is proposed that not only adopts a time-synchronized convergence control framework but also overcomes the lumped uncertainty term, which includes the system fault components, external disturbances, and system uncertainties. A salient feature of this method is that, regardless of the initial state and various uncertainties, each component of the robot manipulator system can simultaneously converge to an equilibrium point. Simulations conducted on a two-link robotic manipulator demonstrate the notable benefits of the designed time-synchronized control method, as evidenced by the comparative results. Full article

The attitude tracking control for spacecraft with limited communication and actuator faults is investigated in this paper by employing event-trigger-based prescribed control. Traditional methods struggle to address arbitrary initial conditions and fault-induced saturation, which both lead to prescribed control singularities, limiting practical deployment. This paper proposes the adhesive-resilient prescribed control (ARPC), which dynamically adjusts the performance envelope by sensing fault and error trends through resilient correction and an adhesive mechanism, respectively. This approach significantly enhances conservatism and robustness, particularly under actuator faults that exceed the saturation level. Additionally, the challenge of balancing high performance with low communication burden under limited resources is addressed. To mitigate communication frequency and bit consumption without sacrificing performance, a z-ary compression event-triggered scheme (CES) is introduced. Compared to existing methods, this work provides substantial improvements in fault tolerance, communication efficiency, and performance adaptability. Numerical experiments demonstrate the superiority of our method in regulating tracking error within a custom envelope and appointed time, regardless of initial conditions, while minimizing communication usage. Full article

This study presents a fault-tolerant control system for Selective Compliance Assembly Robot Arm (SCARA) robots, ensuring operational continuity in cooperative tasks. It is evaluated in five scenarios: normal operation, failures without reconfiguration, and with active reconfiguration. The system employs redundant actuators, differential gears, torque limiters, and rapid detection and reconfiguration algorithms. Simulations in MATLAB R2024a demonstrated reconfiguration times of 0.5 s and reduced trajectory errors (0.0042 m on the X-axis for Robot 1), achieving efficiency above 99%. Nonlinear Model Predictive Controllers (NLMPCs) and Adaptive Sliding Mode Control (ASMC) were compared, with NLMPC excelling in stability and ASMC in precision. The system showcased high productivity in pick-and-place tasks, even under critical failures, establishing itself as a robust solution for industrial environments requiring high reliability and advanced automation. Full article