State Feedback Fault-tolerant Control Research Articles

Robust fault estimation and proportional derivative fault tolerant control for a class of singular systems with interval time‐varying delay and disturbance

SummaryThis paper deals with observer‐based fault estimation (FE) and proportional derivative state feedback fault tolerant control (FTC) schemes for singular systems affected by actuator fault, interval time‐varying delay and external disturbance. Firstly, the system transformation method of constructing the derivative matrix into a full‐rank matrix is adopted to transform the singular system into a normal system, which effectively eliminates the impulse characteristic of the singular system. Secondly, in the design of the dynamic observer, fault estimation utilizes the real‐time output error and its derivative simultaneously, which can achieve better estimation performance when the fault change frequently. Most importantly, the observer‐based FTC adopts a proportional derivative state feedback control, considers disturbance and interval time‐varying delay, and the introduction of state estimation derivative term can eliminate the impulse property of the closed‐loop system, which optimizes the design scheme of the fault‐tolerant controller. The obtained sufficient conditions for stability can be solved by the strict linear matrix inequality (LMI), and the superiority of the conclusions will be further verified by the simulations.

Fuzzy multi-objective fault-tolerant control for nonlinear Markov jump singularly perturbed systems with persistent dwell-time switched transition probabilities

This paper studies the discrete-time slow state feedback fault-tolerant controller design issue for Takagi-Sugeno fuzzy-model-based Markov jump singularly perturbed nonlinear systems, in which transition probabilities of systems subject to persistent dwell-time switching mechanism. In order to eliminate the influence of actuator faults and provide a more flexible control strategy, a multi-objective fault-tolerant controller is designed to ensure the stability of the system and meet the requirements of various performance indexes. The goal is to establish some sufficient conditions, which ensure the mean-square exponential stability and the extended dissipativity performance of the closed-loop system. Furthermore, the gains of the designed controller can be obtained by solving the problem of convex optimization. Finally, the availability of the designed controller is demonstrated by a numerical example and a tunnel diode circuit system.

Velocity-Free State Feedback Fault-Tolerant Control for Satellite with Actuator and Sensor Faults

A velocity-free state feedback fault-tolerant control approach is proposed for the rigid satellite attitude stabilization problem subject to velocity-free measurements and actuator and sensor faults. First, multiplicative faults and additive faults are considered in the actuator and the sensor. The faults and system states are extended into a new augmented vector. Then, an improved sliding mode observer based on the augmented vector is presented to estimate unknown system states and actuator and sensor faults simultaneously. Next, a velocity-free state feedback attitude controller is designed based on the information from the observer. The controller compensates for the effects of actuator and sensor faults and asymptotically stabilizes the attitude. Finally, simulation results demonstrate the effectiveness of the proposed scheme.

Robust fault estimation and fault-tolerant control for nonlinear Markov jump systems with time-delays

The problem of the robust fault estimation and robust fault-tolerant control, for a class of nonlinear time-delayed Markov jump systems (MJSs) with both actuator and sensor faults, was studied. Firstly, by extending the system state, the actuator fault state vector, the sensor fault state vector and the original system state vector were extended to auxiliary state variables, and the original system was extended to a generalized system. Then, for the singular system, a generalized observer was designed to achieve the simultaneous estimation of its actuator faults, sensor faults and original system state. In addition, based on the observer estimation, a state feedback fault-tolerant controller was designed to make the closed-loop system stable and meet certain performance indicators. By solving linear matrix inequality, sufficient conditions for the existence of generalized observer and fault-tolerant controller were given. Finally, a numerical example and a practical example were given to demonstrate the effectiveness of the proposed approach.

A Passive Fault-Tolerant Switched Control Approach for Linear Multivariable Systems: Application to a Quadcopter Unmanned Aerial Vehicle Model

Abstract This paper proposes synthesis algorithms for the design of passive state- and output-feedback fault-tolerant controllers. Sufficient conditions for the existence and the construction of such fault-tolerant controllers are given in terms of linear matrix inequalities (LMIs) which can be solved efficiently. The state-feedback fault-tolerant controller consists of a family of state-feedback gains switched appropriately according to a stabilizing switching signal so that the closed-loop system satisfies a performance requirement expressed in terms of system L2 norm. Similarly, the output feedback controller consists of a family of full-order linear, time-invariant controllers switched according to a stabilizing signal that depends only on the controller states. Both approaches are passive in the sense that they do not rely on the detection and/or the estimation of the faults. The proposed approaches are tested on a nonlinear model of a quadcopter. Simulation results show that satisfactory stability, tracking, and disturbance rejection are maintained despite of time-varying actuator faults.

Design and Analysis of Several State-Feedback Fault-Tolerant Control Strategies for Semi-Active Suspensions

Abstract The design of State-Feedback Fault Tolerant control for Semi-Active Suspension Systems is considered in this work, that exploits diverse simple-to-implement approaches. The suspension damper is assumed to undergo multiplicative (time-varying) faults, that can be estimated by (four) modular fault estimation observers. With these fault estimations, active fault tolerant control (FTC) schemes can be synthesized, based on the reconfiguration of nominal State-Feedback policies. Seven approaches are discussed: i) Direct fault compensation; ii) Pole placement compensation; iii) Fault-dependent pole placement; iv) Linear-fault-dependent Linear Quadratic Regulator (LQR) design; v) Polynomially-fault-dependent LQR parameters; vi) LQR with Fault-dependent controlled outputs; vii) Heuristic (vehicle-oriented) fault-dependent LQR synthesis. The performances of these methods are analysed and compared through realistic and high-fidelity simulations. Results show the overall good operation of the latter approaches to compensate fault events and maintain performances.

Sensor Fault Estimation and Fault-Tolerant Control for a Class of Takagi-Sugeno Markovian Jump Systems with Partially Unknown Transition Rates Based on the Reduced-Order Observer

This paper addresses the problem on sensor fault estimation and fault-tolerant control for a class of Takagi-Sugeno Markovian jump systems, which are subjected to sensor faults and partially unknown transition rates. First, the original plant is extended to a descriptor system, where the original states and the sensor faults are assembled into the new state vector. Then, a novel reducedorder observer is designed for the extended system to simultaneously estimate the immeasurable states and sensor faults. Second, by using the estimated states obtained from the designed observer, a statefeedback fault-tolerant control strategy is developed to make the resulting closed-loop control system stochastically stable. Based on linear matrix inequality technique, algorithms are presented to compute the observer gains and control gains. The effectiveness of the proposed observer and controller are validated by a numerical example and a compared study, respectively, and the simulation results reveal that the proposed method can successfully estimate the sensor faults and guarantee the stochastic stability of the resulting closed-loop system.

Observer based fault tolerant control for a class of Two-PMSMs systems

In this paper, an observer-based state-feedback fault-tolerant controller is proposed for two coupling permanent magnet synchronous motors (PMSMs) system. The controller compensates the actuator faults and allows the system states to track the reference states corresponding to the output of the original two-PMSMs system. To design such a controller, the information of system actuator faults are required. Then, a robust adaptive observer is designed to estimate the system actuator faults firstly. Next, by setting the reference outputs the equilibrium control inputs and reference speeds are computed based on the mathematic model of the two-PMSMs system. Meanwhile, the variation dynamic model is derived. Additionally, the robust stability of the closed-looped system with fault-tolerant controller is analyzed via the Lyapunov theory and interval matrix. Sufficient stability conditions and the gain matrix of the fault-tolerant controller are obtained by solving the linear matrix inequalities (LMIs). Finally, simulation results are presented to illustrate the effectiveness of the proposed observer and fault tolerant control (FTC) scheme.

Optimal Fault-Tolerant Control against Descriptor Time-Varying Systems with Nonlinear Input

The problem of optimal fault-tolerant control for a class of descriptor time-varying systems with nonlinear input is considered. Based on the Lyapunov stability theorem, the sufficient conditions of the stability are obtained when the system is normal and ineffective. Furthermore, the fault-tolerant control of the systems is carried out in two cases, and the state feedback fault-tolerant controller is obtained to satisfy the quadratic performance index and reach the minimum value in order to achieve the optimal fault-tolerant control. Finally, the validity of the proposed approach is illuminated by a numerical example.

Prescribed Performance Fault-Tolerant Control of Uncertain Nonlinear Systems With Unknown Control Directions

A low-complexity state feedback fault-tolerant control scheme guaranteeing prescribed tracking performance is proposed for a family of uncertain nonlinear systems with unknown control directions. Contrary to the current state-of-the-art, novel error transformation functions and new update laws related to performance functions are introduced to the control design such that no compensators or approximation structures are needed, in spite of actuation faults, component faults, and unknown nonlinearities. The proposed method is verified via a simulation on an inverted pendulum.

Fuzzy adaptive state-feedback fault-tolerant control for switched stochastic nonlinear systems with faults

In this paper, the fault-tolerant control (FTC) problem is investigated for a class of uncertain switched stochastic nonlinear systems. The controlled system contains unknown nonlinear functions and actuator faults, which are modeled as both lock-in-place and loss of effectiveness. With the help of fuzzy logic systems to approximate the unknown nonlinear functions and by utilizing the common Lyapunov function (CLF) method, a fuzzy adaptive state-feedback fault-tolerant tracking control approach is developed. It is shown that all the variables of the closed-loop system are semi-globally uniformly bounded (SGUUB) in probability, the tracking error converges to an arbitrary small neighborhood of the origin. A simulation is given to demonstrate the effectiveness of the proposed approach.

Adaptive Observer-Based Fault-Tolerant Control Design for Uncertain Systems

This study focuses on the design of the robust fault-tolerant control (FTC) system based on adaptive observer for uncertain linear time invariant (LTI) systems. In order to improve robustness, rapidity, and accuracy of traditional fault estimation algorithm, an adaptive fault estimation algorithm (AFEA) using an augmented observer is presented. By utilizing a new fault estimator model, an improved AFEA based on linear matrix inequality (LMI) technique is proposed to increase the performance. Furthermore, an observer-based state feedback fault-tolerant control strategy is designed, which guarantees the stability and performance of the faulty system. Moreover, the adaptive observer and the fault-tolerant controller are designed separately, whose performance can be considered, respectively. Finally, simulation results of an aircraft application are presented to illustrate the effectiveness of the proposed design methods.