Output Feedback Fault-tolerant Control Research Articles

Integrated Fault Estimation and Accommodation Design for Discrete-Time Takagi–Sugeno Fuzzy Systems With Actuator Faults

This paper addresses the problem of integrated robust fault estimation (FE) and accommodation for discrete-time Takagi–Sugeno (T–S) fuzzy systems. First, a multiconstrained reduced-order FE observer (RFEO) is proposed to achieve FE for discrete-time T–S fuzzy models with actuator faults. Based on the RFEO, a new fault estimator is constructed. Then, using the information of online FE, a new approach for fault accommodation based on fuzzy-dynamic output feedback is designed to compensate for the effect of faults by stabilizing the closed-loop systems. Moreover, the RFEO and the dynamic output feedback fault-tolerant controller are designed separately, such that their design parameters can be calculated readily. Simulation results are presented to illustrate our contributions.

Static output feedback based fault accommodation design for continuous-time dynamic systems

This article addresses the integrated fault estimation (FE) and accommodation problem for continuous-time dynamic systems. First, using a specific system decomposition, we propose a new multi-objective reduced-order FE observer (RFEO), whose application range is wider than the existing adaptive and sliding mode ones. FE performances are further enhanced by introducing slack variables to reduce the conservatism generated by the direct design method. Finally, with the help of both system decomposition and slack variable techniques, a static output feedback fault tolerant controller (SOFFTC) design, whose sufficient condition is given in terms of linear matrix inequalities, is proposed to guarantee the stability of the closed-loop system in the presence of faults. Moreover, the RFEO and the SOFFTC are designed separately, so that their design parameters can be calculated easily. Simulation results of an aircraft application are presented to illustrate our contributions.

Fault-Tolerant Control for LPV systems based on Fault Compensator

AbstractThis paper proposes a fault-tolerant control (FTC) scheme for polytopic linear parameter varying (LPV) systems. We first propose a fault compensator whose structure is simple, but effective against actuator faults. Then, in order to show its basic idea, we consider a state feedback FTC scheme based on the fault compensator. Next, the FTC algorithm is extended to output feedback FTC scheme. The FTC scheme for LPV systems involves a fault compensator based on the estimated fault and a robust observer based on linear matrix inequality (LMI). The proposed FTC method is applicable for a variety of systems and guarantees the robust stability of the system in the event of actuator faults. Numerical examples are given to demonstrate its effectiveness.

Friction compensation as a fault-tolerant control problem

The control of systems that involve friction presents interesting challenges. Recent research has focused on detailed modelling of friction phenomena in order to use robust on-line friction compensation procedures, attempting to cancel out the friction force effect in the feedback control of a mechanical or mechatronic system. However, the friction modelling problem remains a very difficult challenge and this article proposes a new approach to friction compensation which is based on the theory of robust fault estimation. The friction forces acting in a dynamic system can be viewed as actuator faults with time-varying characteristics to be estimated and compensated within an output feedback fault-tolerant control (FTC) scheme, so that the limitations arising from the use of a friction model are obviated. The friction (fault) estimation problem is hence embedded inside a control system with required stability, and performance robustness. This can be a significant advantage over well-known model-based friction compensation methods in which detailed modelling of friction phenomena is essential and for which robustness with respect to friction characteristics is difficult to achieve using non-linear models.

Observer-based integrated robust fault estimation and accommodation design for discrete-time systems

In this article, a challenging issue on observer-based integrated robust fault estimation and accommodation for a class of discrete-time uncertain nonlinear systems is studied. First, a multiobjective augmented fault estimation observer (AFEO) containing an α-exponential stability performance index and an H ∞ performance index is proposed not only to guarantee the convergence speed of fault estimation but also to restrict the influence of uncertainties with respect to the fault estimation error as much as possible. Then, by introducing a slack matrix, new results are obtained to reduce the conservatism generated by the conventional multiobjective design method. Furthermore, a robust fault tolerant controller based on the dynamic output feedback is designed to guarantee the stability of the closed-loop system in the presence of faults. Moreover, the AFEO and the dynamic output feedback fault tolerant controller (DOFFTC) are designed separately and their performances are considered respectively. Finally, the simulation results of a practical system are presented to illustrate the effectiveness of the proposed design techniques.

Dynamic Output Feedback-Fault Tolerant Controller Design for Takagi–Sugeno Fuzzy Systems With Actuator Faults

This paper addresses the problem of robust fault estimation and fault tolerant control (FTC) for Takagi-Sugeno (T-S) fuzzy systems. A fuzzy-augmented fault estimation observer (AFEO) design is proposed to achieve fault estimation of T-S models with actuator faults. Furthermore, based on the information of online fault estimation, an observer-based dynamic output feedback-fault tolerant controller (DOFFTC) is designed to compensate for the effect of faults by stabilizing the closed-loop system. Sufficient conditions for the existence of both AFEO and DOFFTC are given in terms of linear matrix inequalities. Simulation results of an inverted pendulum system are presented to illustrate the effectiveness of the proposed method.

Dynamic Output Feedback Fault-tolerant Control for Networked Control System with Random Delays

In this paper, the problem of dynamic output feedback fault-tolerant control for networked control system with random delays and actuator fault is studied. Considering the stochastic time-delay occurs in two channels which between sensor and controller, and between controller and actuator, networked control system with possible actuator fault is modeled as finite states discrete-time Markovian jump linear system with two modes. Based on this model, the necessary and sufficient condition on the stochastic stability of networked control system with random delays and actuator fault is given, and the corresponding dynamic output controller design procedure is proposed via the cone complementarity linearization method. Finally, the numerical example and simulations have demonstrated the validity of the proposed results.