Dynamic Output Feedback Based Active Decentralized Fault-Tolerant Control for Reconfigurable Manipulator with Concurrent Failures

This paper is concerned with analyzing a novel model transformation of discrete-time Takagi-Sugeno (T-S) fuzzy systems with time-varying delays and applying it to dynamic output feedback (DOF) controller design. A new auxiliary model is proposed by employing a new approximation for time-varying delay state, and then delay partitioning method is used to analyze the scaled small gain of this auxiliary model. A sufficient condition on discrete-time T-S fuzzy systems with time-varying delays, which guarantees the corresponding closed-loop system to be asymptotically stable and has an induced l 2 disturbance attenuation performance, is derived by employing the scaled small gain theorem. Then the solvability condition for the induced l 2 DOF control is also established, by which the DOF controller can be found by solving a set of linear matrix inequalities (LMIs).

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This paper proposes a novel fault-tolerant tracking control strategy for over-actuated systems subject to actuator fault, control input saturation and external disturbance. The proposed method integrates the effect of actuator saturation and the actuator fault into a generalized disturbance. The generalized disturbance is considered as an auxiliary state vector to construct an augmented system. Based on the augmented system, an $H$ ∞ dynamic output feedback controller is designed to achieve fault-tolerant control. The main advantage of the proposed method is that it can achieve robust fault-tolerant control without depending on the fault diagnosis module and on-line control allocation algorithm. The design conditions are formulated as a set of linear matrix inequalities, which can be solved efficiently. Simulation results of a flight vehicle are given to demonstrate the effectiveness of the proposed method.

This paper considers the design problem of dynamic output feedback control for fractional-order (FO) Takagi-Sugeno fuzzy systems with uncertain parameters. Via the application of FO system stability theory, robust control method and the linear matrix inequality techniques, sufficient conditions are given for the stability analysis and the existence of the dynamic fuzzy output feedback controllers. The dynamic output feedback controller designed here guarantees the robust stability of the closed-loop system. Finally, a fractional order chaotic system simulation example is given to illustrate the effectiveness of the design approach here.

Multiple intermittent fault estimation and tolerant control for switched T-S fuzzy stochastic systems with multiple time-varying delays

This paper considers the problem of adaptive reliable guaranteed cost controller design for linear time-delay systems against actuator faults via dynamic output feedback. Based on indirect adaptive method, a new reliable dynamic output feedback controller is established. The controller gains are affinely dependent on the estimations of fault parameters, which are updating automatically according to the proposed adaptive laws. New delay-dependent sufficient conditions for the existence of the reliable guaranteed cost dynamic output feedback controller are derived in terms of linear matrix inequalities, which have less conservativeness than the corresponding reliable dynamic output feedback controller with fixed gains. An example is presented to show the effectiveness of the proposed method.

Dynamic output feedback-based fault-tolerant control design for T-S fuzzy systems with model uncertainties

SummaryThis paper addresses the issue of fault estimation and accommodation for a discrete‐time switched system with actuator faults. Here, we assume that the sojourn probabilities are known a priori. By using the reduced‐order observer method, the sojourn probability approach, and the Lyapunov technique, a fault estimation algorithm is obtained for the considered system. The main objective of this work is to design a dynamic output feedback fault‐tolerant controller based on the obtained fault estimation information such that the closed‐loop discrete‐time switched system with available sojourn probabilities is robustly mean‐square stable and satisfies a prescribed mixed and passivity disturbance attenuation level in the presence of actuator faults. More precisely, a dynamic output feedback fault‐tolerant controller is established in terms of linear matrix inequalities. Finally, numerical examples are provided to illustrate the usefulness and effectiveness of the proposed design technique.

The design of an accurate fault-tolerant control fault-tolerant control is still an active researches of switched hybrid system whose switching mechanism is unknown. In this paper, a new approach is proposed to deal with switching mode estimation and control problems for switched system subject to actuator faults and disturbances. First, the switching mode is estimated off-line using the Chiu clustering algorithm. Then, actuator fault estimation is proposed using data-based projection approach based on performance measures that allow fault estimation without relying on mathematical models and fault assumptions. Second, a novel switching control strategy is developed for actuator fault compensation and recovering the desired performances. These strategy integrate a set of controllers, corresponding to a set of partial modes to design a bank of switching control laws, compensating for the actuator fault effect and attenuating the sinusoidal disturbance. A new linear matrix inequality is proposed to compute control gains based on Lyapunov stability. This approach allows finding the optimal control gains matrices and ensure both actuator fault compensation and disturbance attenuation. Simulation results of two numerical examples shows the effectiveness of the proposed estimation and control strategies in spite of the presence of actuator faults and sinusoidal disturbance.

Adaptive fault-tolerant shape control for nonlinear Lipschitz stochastic distribution systems

The problem of robust stabilisation is considered for uncertain systems using linear static output feedback (SOF) controllers and linear dynamical output feedback (DOF) controllers with fixed order. The existence conditions of output feedback controllers are given by matrix inequalities and result in some nonlinear optimisation problems. A class of uncertain plants whose nominal systems are minimal phase with a full row rank can be robustly stabilised by an SOF controller and DOF controller with any order, and controllers can be obtained by solving some linear matrix inequalities (LMIs). The method is demonstrated by two numerical examples

This paper focuses on multiple delay-dependent noise-to-state stability (NSS) for a class of switched random nonlinear systems against uncertainty terms and intermittent sensor and actuator faults. External disturbances, nonlinear functions, as well as measurement noise, are also taken into account. This is the first attempt to achieve dynamic output feedback controller design for uncertain switched random nonlinear systems subject to intermittent sensor and actuator faults. First, a controller is established to perform passive fault-tolerant control (FTC). Random systems are more common than Ito stochastic systems. Thus, compared with the previous works, the proposed controller has a wider application scope and is more feasible. Next, an augmented closed-loop system is exhibited to realize NSS. Moreover, a piecewise Lyapunov function is utilized with less conservatism than common Lyapunov function. The delay dependent stability conditions are gathered via linear matrix inequalities (LMIs) and controller matrices are earned. At last, the novelty and validity of the approach suggested in this paper are demonstrated through two simulation examples.

In this paper, the integrated design problem of Fault Estimation (FE) and Fault Tolerant Control (FTC) for saturated systems is considered. The system suffers from input saturation and L2-bounded disturbances. To design an adaptive observer-based FE, the actuator output measurements are not used, when the actuator is saturated, there exist new interactions between FE and FTC. In such a case the separation principle for FE and FTC design does not hold anymore. In this paper, a method is introduced for integrated design of FE and FTC, which guarantees boundedness stability of such a system. To extract sufficient conditions for stability and minimum L2-gain performance for disturbance rejection, the Modified Sector Condition (MSC) is employed for saturation modeling. Also, Quadratic Polytopic Differential Inclusion (QPDI) approach is developed for the comparative study. All conditions are cast as Linear Matrix Inequality(LMIs) that can be evaluated in a single step. In a numerical example, the feasibility of the introduced method for stability guarantee is demonstrated and performance characteristics of FE and FTC in disturbance rejection are compared for both modeling approaches.

This paper investigates the fault estimation and fault tolerant control (FTC) for discrete time nonlinear system with multiple bounded state delay using the Takagi-Sugeno (T-S) fuzzy model. First, a fuzzy-fault estimation observer (FFEO) design is proposed to achieve fault estimation of T-S models with actuator faults. Based on the information of online fault estimation, a state feedback-fault tolerant controller (SFFTC) using the estimate of state is designed to compensate the effect of faults by stabilizing the closed-loop system. The disturbance rejection attenuation is constrained to a given level using a Hœ-performance index. Sufficient conditions are established for the existence of the desired (FFEO) and (SFFTC) in terms of linear-matrix inequalities (LMIs). An example is given to illustrate the effectiveness and applicability of the proposed method.

Robust fault tolerant tracking controller design for a VTOL aircraft