Fault-tolerant Stabilization Research Articles

Fuzzy Adaptive Fault-Tolerant Stability Control Against Novel Actuator Faults and Its Application to Mechanical Systems

Fuzzy Adaptive Fault-Tolerant Stability Control Against Novel Actuator Faults and Its Application to Mechanical Systems

Robust fault-tolerant control of a class of uncertain nonlinear switched systems with actuator saturation

This paper addresses the robust fault-tolerant control problem for a class of uncertain nonlinear switched systems with actuator saturation. Our aim is to design a switching law and a robust fault-tolerant control law for guaranteeing that the closed-loop system is asymptotically stabilizable, while at the same time the attraction domain estimation is as large as possible. By using the multiple Lyapunov functions method, sufficient conditions for robust fault-tolerant stabilisation are proposed for the closed-loop system. Then, when some scalar parameters are given in advance, the problem of fault-tolerant controller design and attraction domain estimation is transformed into a convex optimisation problem with linear matrix inequality (LMI) constraints. Finally the validity of the proposed design method is verified by a numerical example.

Spacecraft Attitude Stabilization Control with Fault-Tolerant Capability via a Mixed Learning Algorithm

The issue of active attitude fault-tolerant stabilization control for spacecrafts subject to actuator faults, inertia uncertainty, and external disturbances is investigated in this paper. To robustly and accurately reconstruct actuator faults, a novel mixed learning observer (MLO) is explored by combining the iterative learning algorithm and the repetitive learning algorithm. Moreover, to guarantee robust spacecraft attitude fault-tolerant stabilization, by synthesizing the mixed learning algorithm with the sliding mode controller, a novel mixed learning sliding-mode controller (MLSMC) is designed based on the separation principle, in which the mixed learning algorithm is used to update composite disturbances online, including fault errors, inertia uncertainty, and external disturbances. Finally, a numerical example is provided to demonstrate the effectiveness and superiority of our proposed spacecraft attitude fault-tolerant stabilization control approach.

Spacecraft attitude fault-tolerant stabilization against loss of actuator Effectiveness: A novel iterative learning sliding mode approach

This paper investigates the attitude fault-tolerant stabilization problem for a spacecraft subjected to its actuator effectiveness loss, inertia uncertainties and space disturbances. A novel Iterative Learning Sliding Mode Observer (ILSMO) is proposed to reconstruct the actuator effectiveness factors robustly and accurately by combining the P-type iterative learning algorithm with the sliding mode approach. Based on the reconstructed fault signals, an Iterative Learning Sliding Mode Controller (ILSMC) is designed to guarantee the closed-loop spacecraft attitude fault-tolerant stabilization by compensating for its lumped disturbance. The ILSMO and ILSMC stabilities are guaranteed using the Lyapunov direct approach, respectively. Finally, the numerical simulation results show that the proposed ILSMO-ILSMC-based spacecraft attitude fault-tolerant stabilization method is effective and superior.

Data-Driven Learning-Based Fault Tolerant Stability Analysis

In this paper, a new data-driven learning method is investigated based on the dynamical data of the system. A regularized regression wavelet (RRW) approach is proposed to optimize the learning result for the system fault. Based on the optimizing results, a fault tolerant stability scheme is given. Then, the efficiency of the proposed technique is verified by a vertical take-off and landing (VTOL) aircraft stability example.

Fault-Tolerant Stability Control for Independent Four-Wheel Drive Electric Vehicle Under Actuator Fault Conditions

Various torque distribution and stability control algorithms have been studied along with the development of four-wheel drive vehicles. But, most of those algorithms focus only on performance improvement. Since the independent four-wheel drive system is based on four drive motors, faults can occur in a motor or an inverter. If a fault occurs, the vehicle stability is not guaranteed and a fatal accident can occur. In this study, the fault-tolerant stability control algorithm for remaining healthy motors is proposed. This fault-tolerant control (FTC) system contains torque distribution and stability control algorithms. For accurate control of motor allocation, driving conditions such as under/over-steering, and steering direction should be considered, as well as vehicle condition such as fault motor location and motor performance limits. The proposed FTC is evaluated with two fault conditions (e.g., front motor fault, rear motor fault) under straight acceleration and constant steering acceleration scenarios. The behavior characteristics and driving risks caused by failures of motors while driving are analyzed. Also, the FTC algorithm is accurately follow a desired path within a minimum error range that the driver can cover.

Reliable Control for a Class of Nonlinear Time-Delay Systems Against Actuator Faults With Application to Suspension Control

In this article, the fault-tolerant stabilization control problem is investigated for a general class of time-varying delay pure-feedback uncertain stochastic nonlinear systems with both random noises and actuator faults. Unlike most of the existing results, the fault scaling factors for each actuator are described by random functions related to the Markovian process, which is much more practical. In addition, due to relevant terms for the transition rate and time delay existing in the infinitesimal operator acting on the Lyapunov–Krasovskii functional, how to deal with these terms is much more challenging. By employing the method of online estimating the fault information from actuators and uncertain parameters arising from the input dead-zone actuators, the proposed adaptive control scheme is effective in the compensation of these unexpected effects and ensures the random stability of the closed-loop systems. Finally, an application example is used for verifying the applicability of the presented approach.

Stabilization of uncertain switched discrete-time systems against actuator faults and input saturation

This paper studies the robust fault-tolerant stabilization problem for a class of uncertain switched discrete-time systems subject to time delays, actuator faults and input saturation by using delta operator approach. By constructing an appropriate Lyapunov–Krasovskii functionals in delta domain, a new set of sufficient conditions is provided for the stability of the delta operator time delay switched systems. More precisely, gain matrices of the fault-tolerant controller can be computed by solving the linear matrix inequalities and the proposed controller can robustly stabilize the uncertain delta operator time delay switched system for all admissible parameter perturbations. Further, in order to obtain a maximal estimate of the domain of attraction, an LMI based optimization algorithm is presented. It is noted that a better control performance can be obtained for small sampling periods by using delta operator approach than using shift operator. Finally, numerical examples with simulation results are presented to illustrate the effectiveness and potential of the developed control design technique.

Integrated Fault-Tolerant Stabilization Control for Satellite Attitude Systems with Actuator and Sensor Faults

In this paper, the problem of integrated fault-tolerant stabilization control is studied for the attitude systems of a rigid satellite with both actuator and sensor faults. Firstly, a virtual observer is designed for the faulty attitude systems of rigid satellite in order to estimate the unknown actuator and sensor faults. Because the virtual observer includes unmeasurable information of the attitude systems, the real observer is then presented. On this basis, an integral sliding-mode fault-tolerant stabilization control approach is proposed by using the estimated fault information, and it not only suppresses the disturbance with a disturbance attenuation level $$\gamma $$ , but also eliminates the effects of actuator and sensor faults. Finally, the effectiveness of the proposed fault-tolerant stabilization scheme is demonstrated in the attitude systems of a rigid satellite subject to the time-varying actuator and sensor faults.

Forecast-Triggered Model Predictive Control of Constrained Nonlinear Processes with Control Actuator Faults

This paper addresses the problem of fault-tolerant stabilization of nonlinear processes subject to input constraints, control actuator faults and limited sensor–controller communication. A fault-tolerant Lyapunov-based model predictive control (MPC) formulation that enforces the fault-tolerant stabilization objective with reduced sensor–controller communication needs is developed. In the proposed formulation, the control action is obtained through the online solution of a finite-horizon optimal control problem based on an uncertain model of the plant. The optimization problem is solved in a receding horizon fashion subject to appropriate Lyapunov-based stability constraints which are designed to ensure that the desired stability and performance properties of the closed-loop system are met in the presence of faults. The state-space region where fault-tolerant stabilization is guaranteed is explicitly characterized in terms of the fault magnitude, the size of the plant-model mismatch and the choice of controller design parameters. To achieve the control objective with minimal sensor–controller communication, a forecast-triggered communication strategy is developed to determine when sensor–controller communication can be suspended and when it should be restored. In this strategy, transmission of the sensor measurement at a given sampling time over the sensor–controller communication channel to update the model state in the predictive controller is triggered only when the Lyapunov function or its time-derivative are forecasted to breach certain thresholds over the next sampling interval. The communication-triggering thresholds are derived from a Lyapunov stability analysis and are explicitly parameterized in terms of the fault size and a suitable fault accommodation parameter. Based on this characterization, fault accommodation strategies that guarantee closed-loop stability while simultaneously optimizing control and communication system resources are devised. Finally, a simulation case study involving a chemical process example is presented to illustrate the implementation and evaluate the efficacy of the developed fault-tolerant MPC formulation.

Forecast-Triggered Fault-Tolerant Model Predictive Control of Nonlinear Processes

In this work, we consider the problem of fault-tolerant stabilization of constrained nonlinear processes controlled over resource-constrained sensor-controller communication networks and subject to control actuator faults. A methodology for the design of resource-aware Lyapuonv-based model predictive control (MPC) systems that achieve the fault-tolerant stabilization objective with reduced sensor-controller communication is presented. In this approach, the control action is computed by solving on-line a finite-horizon optimal control problem based on an uncertain model of the plant subject to appropriate Lyapuonv-based stability constraints. The stability constraints are designed to ensure the desired closed-loop stability and performance properties in the presence of faults, and an explicit characterization of the state space region where fault-tolerant stabilization is guaranteed is obtained in terms of the fault size, the choice of the controller design parameters and the size of the plant-model mismatch. To keep sensor-controller communication to a minimum, a forecast-triggered communication strategy is used to determine when communication should be suspended or restored over the network. In this strategy, an update of the model state in the predictive controller using the sensor measurements at a given sampling time is triggered only when the Lyapunov function is forecasted to breach a certain threshold over the next sampling interval. The update-triggering threshold is derived using Lyapunov techniques and is explicitly parameterized in terms of the fault and a suitable fault accommodation parameter. Based on this characterization, fault accommodation strategies that guarantee closed-loop stability while simultaneously optimizing control and communication system resources are devised. Finally, the developed MPC formulation is illustrated using a chemical process example.

Stabilization of Continuous-Time Random Switching Systems via a Fault-Tolerant Controller

This paper focuses on the stabilization problem of continuous-time random switching systems via exploiting a fault-tolerant controller, where the dwell time of each subsystem consists of a fixed part and random part. It is known from the traditional design methods that the computational complexity of LMIs related to the quantity of fault combination is very large; particularly system dimension or amount of subsystems is large. In order to reduce the number of the used fault combinations, new sufficient LMI conditions for designing such a controller are established by a robust approach, which are fault-free and could be solved directly. Moreover, the fault-tolerant stabilization realized by a mode-independent controller is considered and suitably applied to a practical case without mode information. Finally, a numerical example is used to demonstrate the effectiveness and superiority of the proposed methods.

Adaptive Fault Tolerant Stabilization for Uncertain MIMO Systems with Actuation Failures

This paper considers the state stabilization problem for a class of non-affine uncertain MIMO systems with actuation failures. An adaptive robust fault-tolerant control is developed to compensate the affect of uncertainties, actuator failures. And theoretical analysis based on a Lyapunov-like approach demonstrates that, under some proper conditions, the close-loop system would be stabilized and ultimately uniformly bounded state error could be guaranteed by the controller. Further, the proposed controller is no need for on-line fault detection and diagnosis unit, and inexpensive to compute. At last, numerical simulations are provided to validate and illustrate the benefits and effectiveness of the proposed control scheme.

Adaptive fault-tolerant stabilization for nonlinear systems with Markovian jumping actuator failures and stochastic noises

In this paper we consider the fault-tolerant stabilization problem for a class of nonlinear systems with uncertain parameters. Uncertainties caused by Markovian jumping actuator failures and stochastic noises are also taken into consideration. Different from most existing results, the number of actuator failures may be infinite and stochastic functions related to multi-Markovian variables have been introduced to denote the failure scaling factors for the actuators, which is practical, but challenging. Three main difficulties arise: first is how to establish fundamentals for systems involving multi-Markovian variables and stochastic noises, including the joint transition probability, the infinitesimal generator, the existence and uniqueness of the solution and so on; second is how to handle the extra transition rate related terms appearing in the infinitesimal generator of the Lyapunov function; last is how to cope with the involved higher order Hessian term in the Itô stochastic differentiation. By proposing a new adaptive fault tolerant control scheme, the boundedness in probability of all the closed-loop signals has been ensured. An example of altitude fault-tolerant control for a generic hypersonic air vehicle is presented to show the effectiveness of the proposed scheme.

Robust fault‐tolerant control for uncertain delta operator switched systems

This study addresses two issues of robust fault-tolerant stabilisation with circular disk pole constraints for uncertain delta operator switched systems with actuator faults. The first computes the dwell time and proposes a state feedback controller design approach to stabilise the considered switched system. The second solves the V-stabilisation problem based on state switching strategy. Finally, an illustrative example is provided to validate the feasibility and effectiveness of the proposed approaches.

Fault-tolerant Stabilization for Linear System with Time Delay

In this note, the FTC problem of time-delay systems with the special sensor model of failure is investigated. Firstly, based on Lyapunov stability theorem, through constructing a proper LKF and using integral inequality, the stability condition of the closed-loop system is obtained. Secondly, by using the nonlinear transformation and the cone complementary linearization algorithm, the controller existence condition of time-delay system in terms of LMIs is obtained, which guarantee the asymptotically stable of the closed-loop systems even if the sensor faults occur, and the controller parameters are also given. Finally, an example is given to show the effectiveness of the proposed methods in this paper.

Delayed-State-Feedback Fault-Tolerant Control for Fuzzy Markovian Jumping Systems

This paper is concerned with the robust delayed-state-feedback fault-tolerant control problem for fuzzy markovian jump systems with time-varying delay. A new criterion of delayed-dependent robust fault-tolerant stabilization for such systems is established in terms of linear matrix inequalities (LMIs) by using Lyapunov stability theory and free-weighting matrix methods. Based on the obtained criterion, designed hybrid controller combining state feedback and delayed state feedback can guarantee robust asymptotic stability in mean square sense for the resulting closed-loop system not only when all control components are operating well, but also in the presence of some outages of actuators within a prespecified subset of actuators.

Fault-tolerant wide-range stabilisation of a power system

This paper considers the fault-tolerant stabilisation of a power system over a wide range of operating conditions via excitation and governor controllers. A simple technique is presented to maintain stability when both controllers act together and when either one of the two controllers fails. The dynamics of a power system operating at various loads is treated as an interval (uncertain) plant. The problem of designing power system controllers with a general structure, which stabilise the interval plant, is converted to a simple stabilisation problem for only four Kharitanov polynomials (as compared to the 16 plant theorem with first order controllers). A single machine infinite bus system is considered to demonstrate the suggested technique. Stability tests show the robustness of the proposed controller.

Detection and management of actuator faults in controlled particulate processes using population balance models

This paper presents a methodology for the design of an integrated fault detection and fault-tolerant control (FD-FTC) architecture for particulate processes described by population balance models (PBMs) with control constraints, actuator faults and a limited number of process measurements. The architecture integrates model-based fault detection, state estimation, nonlinear feedback and supervisory control on the basis of an appropriate reduced-order model that captures the dominant dynamics of the process and is obtained through application of the method of weighted residuals. The architecture comprises a family of control configurations together with a fault detection filter and a supervisor. For each configuration, a stabilizing output feedback controller with well-characterized stability properties is designed through the combination of a state feedback controller and a state observer that uses the available measurements of principal moments of the particle size distribution (PSD) and the continuous-phase variables to provide appropriate state estimates. A fault detection filter that simulates the behavior of the fault-free, reduced-order model is designed, and its discrepancy from the behavior of the actual process state estimates is used as a residual for fault detection. Finally, a switching law based on the stability regions of the constituent control configurations is derived to reconfigure the control system in a way that preserves closed-loop stability in the event of fault detection. Appropriate fault detection thresholds and control reconfiguration criteria that account for model reduction and state estimation errors are derived for the implementation of the FD-FTC architecture on the particulate process. Finally, the methodology is applied to the problem of constrained, actuator fault-tolerant stabilization of an unstable steady-state of a continuous crystallizer.

Coordinating feedback and switching for control of spatially distributed processes

This work proposes a methodology for coordinating feedback controller synthesis and actuator configuration switching in control of spatially-distributed processes, described by highly dissipative partial differential equations (PDEs) with actuator constraints. Under the assumption that the eigenspectrum of the spatial differential operator can be partitioned into a finite slow set and an infinite stable fast complement, Galerkin's method is initially used to derive a finite-dimensional system (set of ordinary differential equations (ODEs) in time) that captures the dominant dynamics of the PDE system. Using this ODE system, a stabilizing nonlinear feedback controller is designed, for a given actuator configuration, and an explicit characterization of the corresponding stability region is obtained in terms of the size of actuator constraints and the spatial locations of the actuators. Switching laws are then derived, on the basis of the stability regions, to orchestrate the transition between multiple, spatially-distributed control actuator configurations, in a way that respects actuator constraints, accommodates multiple (possibly conflicting) control objectives and guarantees closed-loop stability. Precise conditions that guarantee stability of the constrained closed-loop PDE system under switching are provided, and the proposed approach is successfully applied to the problem of constrained, fault-tolerant stabilization of unstable steady-states of a representative diffusion-reaction process and a non-isothermal tubular reactor with recycle.