Active Fault-tolerant Tracking Control Research Articles

Active fault-tolerant tracking control for discrete-time switched LPV system based on virtual actuator method

In this paper, the active fault-tolerant tracking control issue is studied for a class of discrete-time switched linear parameter varying system by using the virtual actuator approach. First, a switched gain-scheduled virtual actuator is proposed to improve the faulttolerance performance. Second, in order to obtain better tracking performance, a sub-optimal trajectory recovery target is determined by minimizing the H∞-norm of the virtual actuator's relevant transmission channel. By using the multiple parameter-dependent Lyapunov function approach, sufficient conditions for the tracking closed-loop system and virtual actuator system to be globally uniformly exponentially stable are derived, which also guarantee the desired H∞ performance indices requirement. Finally, effectiveness and applicability of the developed approaches are validated via a GE-90 turbofan-engine model system

A Novel Active Fault-Tolerant Tracking Control for Robot Manipulators with Finite-Time Stability.

Many terminal sliding mode controllers (TSMCs) have been suggested to obtain exact tracking control of robotic manipulators in finite time. The ordinary method is based on TSMCs that secure trajectory tracking under the assumptions such as the known robot dynamic model and the determined upper boundary of uncertain components. Despite tracking errors that tend to zero in finite time, the weakness of TSMCs is chattering, slow convergence speed, and the need for the exact robot dynamic model. Few studies are handling the weakness of TSMCs by using the combination between TSMCs and finite-time observers. In this paper, we present a novel finite-time fault tolerance control (FTC) method for robotic manipulators. A finite-time fault detection observer (FTFDO) is proposed to estimate all uncertainties, external disturbances, and faults accurately and on time. From the estimated information of FTFDO, a novel finite-time FTC method is developed based on a new finite-time terminal sliding surface and a new finite-time reaching control law. Thanks to this approach, the proposed FTC method provides a fast convergence speed for both observation error and control error in finite time. The operation of the robot system is guaranteed with expected performance even in case of faults, including high tracking accuracy, small chattering behavior in control input signals, and fast transient response with the variation of disturbances, uncertainties, or faults. The stability and finite-time convergence of the proposed control system are verified that they are strictly guaranteed by Lyapunov theory and finite-time control theory. The simulation performance for a FARA robotic manipulator proves the proposed control theory’s correctness and effectiveness.

Active fault tolerant tracking control of turbofan engine based on virtual actuator

In this paper, an active fault-tolerant tracking control scheme for the turbofan engine under dynamic and simultaneous actuator faults and sensor faults under disturbances is proposed. First, based on the linear parameter-varying model of the turbofan engine, an H∞ state feedback nominal controller is designed so as to achieve rotor speed tracking control with adaptive gain scheduling characteristics at different working conditions for the turbofan engine. Next, for the control system with simultaneous multiplicative actuator faults and additive sensor faults, a virtual actuator based active fault-tolerant tracking control strategy is developed to reconfigure the system such that it can obtain the similar behavior to the fault-free system without modifying the nominal controller. Specifically, in addition to handle the actuator fault by the virtual actuator, the reconfigured controller adopts a feedforward control signal to compensate for the sensor fault. Besides, in order to guarantee the reconfigured system, a sufficiency criterion is proposed. Finally, simulations have been conducted on a twin-spool turbofan engine to verify the effectiveness of the strategy.

Active fault-tolerant tracking control of a quadrotor with model uncertainties and actuator faults

This paper presents a reliable active fault-tolerant tracking control system (AFTTCS) for actuator faults in a quadrotor unmanned aerial vehicle (QUAV). The proposed AFTTCS is designed based on a well-known model reference adaptive control (MRAC) framework that guarantees the global asymptotic stability of a QUAV system. To mitigate the negative impacts of model uncertainties and enhance system robustness, a radial basis function neural network is incorporated into the MRAC scheme for adaptively identifying the model uncertainties online and modifying the reference model. Meanwhile, actuator dynamics are considered to avoid undesirable performance degradation. Furthermore, a fault detection and diagnosis estimator is constructed to diagnose lossof- control-effectiveness faults in actuators. Based on the fault information, a fault compensation term is added to the control law to compensate for the adverse effects of actuator faults. Simulation results show that the proposed AFTTCS enables the QUAV to track the desired reference commands in the absence/presence of actuator faults with satisfactory performance.

An advanced robust fault-tolerant tracking control for a doubly fed induction generator with actuator faults

Fault-tolerant controller (FTC) designs for doubly fed induction generators (DFIGs) with actuator faults have recently gained considerable attention due to their important role in maintaining the safety and reliability of DFIG-based wind turbines via configured redundancy. The objective of this paper is to propose a novel active fault-tolerant tracking control strategy for a DFIG subject to actuator faults. The proposed strategy consists of first designing a proportional integral observer (PIO) for simultaneous system states and fault estimation and then secondly the FTC, which depends on the estimated states and faults. The objective of such a controller is to drive the state of the system to track a reference state generated by a reference fault-free model (nominal system). In addition, the main results for stability are demonstrated through a quadratic Lyapunov function, formulated in terms of linear matrix inequalities (LMIs) in order to guarantee the stability of the whole closed-loop system and to reduce the actuator fault effects with noise attenuation. Furthermore, the gain matrices of the FTC and the PIO are computed by solving a set of LMIs using the YALMIP toolbox with the SeDuMi solver. Finally, the simulation results under constant and time-varying actuator faults are provided to show the effectiveness of the developed FTC scheme.

Active fault-tolerant tracking control for near-space vehicle attitude dynamics with actuator faults

Based on both adaptive and fuzzy logic techniques, the fault-tolerant tracking problem for near-space vehicle (NSV) with actuator faults is investigated in this paper. First, the nonlinear NSV attitude dynamics is given, which can represent the dynamic characteristics of NSV in both ascent and re-entry phases. The actuator fault under consideration in this study is the loss of effectiveness, and a novel fault detection scheme is presented by designing a nonlinear fault detection observer. In terms of fault detection information and multi-observer technique, a fault isolation scheme is proposed. Taking advantage of a fuzzy logic system (FLS) to approximate the unknown nonlinear function, an adaptive FLS-based fault-tolerant tracking control law is developed to achieve asymptotic output tracking and closed-loop stability of NSV attitude dynamics in spite of the actuator faults. Simulation results are provided to illustrate the feasibility of the proposed fault-tolerant tracking control approach.