Dynamic Event-Based Fuzzy Quantized Fault-Tolerant Control for Cascaded ODE-Belt Systems With Actuator Failures and Quantization

This article is to develop the optimised backstepping (OB) fault-tolerant control for a class of nonlinear strict feedback systems with sensor and actuator failures. The OB strategy is to implement the critic-actor reinforcement learning (RL) in every backstepping step for deriving the optimised virtual and actual controls. However, the sensor and actuator failures will lead to the RL disable because the false information is transmitted in sensor and actuator channels. To address this problem, an adaptive algorithm is developed to estimate the unknown bias parameters. Nevertheless, RL is relevant with the solution of the Hamilton–Jacobi–Bellman (HJB) equation, which is a complex nonlinear equation, if the adaptive estimation algorithm is integrated into RL, it will lead to increase the complexity of algorithm. To alleviate the situation for operating the OB control more smoothly, the RL algorithm is derived according to a simple positive function, which is equivalent to the HJB equation, so that the algorithm complexity can be effectively alleviated. Finally, the proposed control method is verified by the Lyapunov stability analysis and simulation example.

Indirect adaptive fuzzy fault-tolerant tracking control for MIMO nonlinear systems with actuator and sensor failures

A fault tolerant flight control system for sensor and actuator failures using neural networks

A fault-tolerant supervisory control method for dynamic positioning of ships with actuator failures and sensor failures is presented in this paper. Unlike the traditional fault detection and control, fault detection and fault-tolerant controller are designed as a unit in this paper through a supervisor. By introducing a nonlinear estimation error and virtual controller, the sensor failures are separated from the actuator failures in the supervisory control system. It guarantees that the detectability property and matching property of the switched system are satisfied. Firstly, a new extended state observer is designed to match the models of different actuator failures. Secondly, by introducing a virtual controller, the detectability property of the switched system is guaranteed. Finally, a nonlinear estimation error operator is used in the designing of switching logic to guarantee stability of the closed-loop system with sensor failures. When sensor failures and actuator failures occur, we show that all the states of the closed-loop system are guaranteed to be bounded. The effectiveness of the fault-tolerant control is verified by simulation experiments.

T For the networked control system (NCS), the considered system has actuator and sensor failures. In considering the impact of the network delay on system performance, establish a new class of uncertain NCS fault model Then use Lyapunov stability theory, fault-tolerant control theory and the static state feedback, the sufficient conditions for closed-loop NCS possessing robust asymptotically stable against actuator and sensor failure are given . And the robust H-inf fault-tolerant controller design method under the sensor and actuator failures is deduced in terms of linear matrix inequalities (LMI). An numerical simulation is provided to show the effectiveness of the proposed conclusion.

A robust adaptive fault-tolerant control approach to attitude tracking of flexible spacecraft is proposed for use in situations when there are actuator (reaction wheels) failures, external disturbances and unknown inertia-parameter uncertainties. The controller is designed based on a backstepping sliding mode control scheme. It ensures that the equilibrium points in the closed-loop system exhibits uniform ultimate bounded stability in the presence of unknown uncertainties and bounded disturbances, incorporating constraints on actuator failures, whose failure time instants, patterns and values are unknown, as motivated from a practical spacecraft control application. It is proved to be effective also in the presence of disturbance due to the flexibility, provided that appropriate robustness conditions on the controller gains are satisfied. Complete stability and performance analysis are presented and illustrative simulation results of an application to flexible spacecraft show that the high precise attitudes control and vibration suppression are successfully achieved when considering various scenarios of control effect failures.

Because of increased requirements on the reliability, maneuverability and survivability of modern highspeed trains, more and more advanced control theory is applied against actuator failures. The control reallocation and adaptive control have long been attracting research interest in the field of fault-tolerant control, which is reflected in the design and development of powerful and complex control systems against actuator failures. In this paper we investigate the velocity tracking control problem of high-speed trains with multiple vehicles connected through couplers in the case of actuator failures. First, the multiple point-mass model is built and the common actuator failures of the train operation control system are divided into two types: stuck in a fixed value and loss of effectiveness. When plant inputs are stuck in a fixed value, a novel approach based on the control reallocation theory is implemented to ensure the system stability and performance. Meanwhile when the loss of the actuator effectiveness occurs, a robust adaptive fault-tolerant control method is applied. Then, the effectiveness of the proposed approach is also confirmed through numerical simulations based on a train similar to China Railways High-speed 5 (CRH5).

Actuator failure seriously threatens the flight safety of unmanned helicopters. Considering the problem of multiple faults such as actuator bias and failure in unmanned helicopters, a composite fault-tolerant flight control algorithm is proposed. For actuator bias fault, a nonlinear fault observer is designed to estimate it in real time; for actuator failure fault, a same-dimensional auxiliary system is constructed and processed by neural network technology. The composite fault-tolerant flight controller of the unmanned helicopter is designed by backstepping method, and the Lyapunov stability theory is used to prove that the error signals of the closed-loop system are bounded and convergent. Simulation results show that the proposed control algorithm can improve the fault tolerance of the unmanned helicopter when multiple actuator faults occur, ensuring its safe flight.

PurposeThe purpose of this paper is to construct an event-triggered finite-time fault-tolerant formation tracking controller, which can achieve a time-varying formation control for multiple unmanned aerial vehicles (UAVs) during actuator failures and external perturbations.Design/methodology/approachFirst, this study developed the formation tracking protocol for each follower using UAV formation members, defining the tracking inaccuracy of the UAV followers’ location. Subsequently, this study designed the multilayer event-triggered controller based on the backstepping method framework within finite time. Then, considering the actuator failures, and added self-adaptive thought for fault-tolerant control within finite time, the event-triggered closed-loop system is subsequently shown to be a finite-time stable system. Furthermore, the Zeno behavior is analyzed to prevent infinite triggering instances within a finite time. Finally, simulations are conducted with external disturbances and actuator failure conditions to demonstrate formation tracking controller performance.FindingsIt achieves improved performance in the presence of external disturbances and system failures. Combining limited-time adaptive control and event triggering improves system stability, increase robustness to disturbances and calculation efficiency. In addition, the designed formation tracking controller can effectively control the time-varying formation of the leader and followers to complete the task, and by adding a fixed-time observer, it can effectively compensate for external disturbances and improve formation control accuracy.Originality/valueA formation-following controller is designed, which can handle both external disturbances and internal actuator failures during formation flight, and the proposed method can be applied to a variety of formation control scenarios and does not rely on a specific type of UAV or communication network.

Significant number of fatal aircraft accidents in recent years have been linked to component failures. With the predicted increase in air traffic these numbers are likely to increase. With reduction of fatal accidents as motivation, this dissertation investigates design of fault tolerant control systems for aircrafts undergoing sensor and/or actuator failures. Given that the nominal controller may perform inadequately in the event of sensors and/or actuator failure, the feasible approach for such a control scheme is to predesign various controllers anticipating these failures and then switching to an appropriate controller when the failure occurs. This is enabled by the available redundancy in sensing and actuation and allows the system to perform adequately even when these failures occur. The predesign of controllers for sensor and actuator failures is considered. Sensor failures are easily accommodated if certain detectability conditions are met. However, the predesign for actuator failures is not trivial as the position at which the actuators fail is not known a priori. It is shown that this problem can be tackled by reducing it to the classical control problem of disturbance decoupling, in which, the functional control enables the steady state output of dynamical system to reject any disturbance due to the failed actuators. For linear systems, conditions for existence of a controller capable of accommodating these failures can be understood in geometric terms and calculations are linked to solvability of coupled matrix equations. Although control design for aircrafts is done using linear techniques, failures can cause excursions into nonlinear regimes due to ensuing changes in the flight conditions. This dissertation also uses the recent results in the nonlinear regulator theory to address actuator failures in nonlinear systems. The utility of design techniques is illustrated using flight control examples with failures. The symbolic computational tools are developed and are available in the appended disk. A section on the use of variable structure servomechanisms to perform the regulation needed in case of actuator failures is also included.

A switching-free multiple-model approach for adaptive FTC of non-Lipschitz nonlinear uncertain systems under persistent actuator failures

This article discusses cooperative control of a mobile dual flexible manipulator system with asymmetric time-varying output constraints and actuator failures. The shift function and a barrier Lyapunov function (BLF) are used to guarantee output constraints when the initial states of the system violate the prescribed constraints. Moreover, an adaptive fault-tolerant control scheme is developed to deal with actuator failures, while suppressing system’s vibration and achieving cooperative operation. Finally, theoretic analysis proves the uniform bounded stability of the system and numerical simulation verifies the effectiveness of the proposed control method. Note to Practitioners—The purpose of this article is to develop a cooperative dual flexible manipulator system with performance limitations and actuator failures. The system can realize the task of stably grasping and moving a rigid object. The existing research on the grasping task of flexible manipulators only focuses on coordinated operation, which limits the application of the dual flexible manipulator system in practical engineering. To further study the problem, this article considers the output constraints and actuator failures of the dual flexible manipulator system in the actual process and proposes a cooperative fault-tolerant control framework. The control framework uses shift function and BLF to deal with output constraints and adopts adaptive technology to deal with actuator failures. In addition, the cooperative operation task of grasping object with dual flexible manipulators is realized. Simulation shows that this control strategy is feasible.

On Fault-tolerant Control of Dynamic Systems with Actuator Failures and External Disturbances

摘要: 研究执行器故障和外界扰动同时存在时动态系统的容错控制问题, 推广和改进了现有相关结果. 具体包括以下几方面: 所提方法不涉及求解含执行器故障变量(时变且未知)的Lyapunov方程; 在设计和实现本文提出的控制方案时, 不需要对执行器故障范围界值进行人工估算; 能有效抑制执行器故障及有界和无界外部干扰对系统性能的影响. 在一定意义上, 现有相关结果仅是本文的一个特例, 且本文所提方案更有效、更易于设计和实现, 因为它不依赖于故障的任何解析信息, 无需知道执行器故障发生的时间及界值大小等. 关键词: 容错控制 / 执行器故障 / 鲁棒自适应控制 / 无界扰动

An adaptive dynamic inversion control formulation is presented that takes advantage of the inherent dynamic structure of the state-space description of a large class of systems. The formulations impose the exact kinematic differential equations, thereby restricting the adaptation process that compensates for model errors to the acceleration level. The utility of this formulation is demonstrated for the problem of fault tolerance to actuator failures on redundantly actuated systems. The approach incorporates an actuator failure model in the controller formulation, so that actuator failure can be identified as a change in the parameters of the failure model. Tracking of reference trajectories is imposed, and initial error conditions and structured parametric uncertainties are incorporated explicitly in both the plant parameters and the control influence matrix. A numerical example consisting of a nonlinear model of an F-16 type aircraft with thrust vectoring is presented. Simulation results show that the fault-tolerant adaptive controller is capable of simultaneously handling parametric uncertainties, large initial condition errors, and actuator failures while maintaining adequate tracking performance. N recent years, there has been much interest in the development of reconfigurable control systems that can accommodate actuator failures without compromising mission integrity. There has been substantial progress in the development of real-time failure detection and isolation algorithms, system identification after failure, and control reconfiguration techniques in aerospace applications. In Ref. 1, a survey of various reconfigurable flight control methodologies is presented and it is shown that most traditional reconfiguration flight control approaches rely on failure detection and isolation. The complexity of such a system with this feature grows with the increase in the number of failures, and there tends to be a significant possibility of false alarms. 1,2 A different approach to reconfigurable flight control is based on adaptive control theory, in which the adaptive control structure implicitly reconfigures the control law using adaptive estimates of the altered dynamics after failure. 3 In Ref. 3, an adaptive control scheme is presented that uses a linear approximation of the plant model to compute the control, and a neural network based adaptive control law for flight reconfiguration has been developed and successfully flight tested. 4−6 A robust fault-tolerant controller has also been developed to reject state-dependent disturbances. 7 The approach presented in this paper uses a structured nonlinear adaptive dynamic inversion control methodology. Instead of using an explicit failure detection and isolation algorithm, this methodology is based on the adaptive control theory where the controller is constantly updating itself. This methodology is applicable to a general class of nonlinear systems that are affine in the control with uncertain parameters appearing linearly. Fault-tolerance capability is introduced by incorporating a failure model in the controller so that a failure can be identified and compensated for by a change in the parameters of the failure model. First, model reference adaptive control, structured model reference adaptive control, and structured adaptive model inversion