Feedback Fault-tolerant Control Research Articles

Online adaptive policy iteration based fault-tolerant control algorithm for continuous-time nonlinear tracking systems with actuator failures

In this paper, a novel tracking control scheme for continuous-time nonlinear affine systems with actuator faults is proposed by using a policy iteration (PI) based adaptive control algorithm. According to the controlled system and desired reference trajectory, a novel augmented tracking system is constructed and the tracking control problem is converted to the stabilizing issue of the corresponding error dynamic system. PI algorithm, generally used in optimal control and intelligence technique fields, is an important reinforcement learning method to solve the performance function by critic neural network (NN) approximation, which satisfies the Lyapunov equation. For the augmented tracking error system with actuator faults, an online PI based fault-tolerant control law is proposed, where a new tuning law of the adaptive parameter is designed to tolerate four common kinds of actuator faults. The stability of the tracking error dynamic with actuator faults is guaranteed by using Lyapunov theory, and the tracking errors satisfy uniformly bounded as the adaptive parameters get converged. Finally, the designed fault-tolerant feedback control algorithm for nonlinear tracking system with actuator faults is applied in two cases to track the desired reference trajectory, and the simulation results demonstrate the effectiveness and applicability of the proposed method.

Output Feedback Thruster Fault-Tolerant Control for Dynamic Positioning of Vessels Under Input Saturation

In this paper, an output feedback fault-tolerant control (FTC) scheme is presented for the dynamic positioning of vessels subjected to external disturbances, dynamic uncertainties, and thruster saturation constraints under thruster faults. A high-gain observer is constructed to acquire the estimates of vessel velocities. An auxiliary dynamic system is introduced to compensate the effect of the thruster faults and saturation constrains. Neural network with iterative updating laws is employed to approximate the lumped uncertainties caused by unknown environmental disturbances and dynamic uncertainties of vessels. Furthermore, the control allocation is accomplished to distribute the FTC forces and moment among individual thrusters. It is theoretically proved that the derived FTC scheme has the capability to maintain the vessel position at the desired values and guarantees that all signals in the closed-loop control system are uniformly ultimately bounded. Finally, the simulation results demonstrate the effectiveness of the proposed control scheme.

Fault detection and fuzzy tolerant control for complex stochastic multivariable nonlinear systems

Abstract In this paper, the problem of fault-tolerant control (FTC) is investigated for a class of multivariable stochastic nonlinear systems in the strict-feedback form. The considered systems possess unknown nonlinear functions, unmeasured states, virtual control coefficients and actuator faults (bias and gain faults). Neural networks (NNs) are adopted to approximate the unknown nonlinear functions. Then, a state observer is constructed to solve the problem of unmeasured states. The problem of “explosion of complexity” is solved by using dynamic surface control (DSC) method. Based on the combination of Nussbaum gain function with Lyapunov function stability theory, an adaptive NNs output feedback FTC method is developed in the frame of adaptive backstepping design technique. It is shown that all signals in the closed-loop system are proved to be bounded in probability, and the system output can follow the given reference signal well. The effectiveness of the proposed approach is verified by a simulation example.

Fuzzy Adaptive Output Feedback Fault-Tolerant Tracking Control of a Class of Uncertain Nonlinear Systems With Nonaffine Nonlinear Faults

This paper studies the fuzzy adaptive output feedback fault-tolerant control (FTC) problem for a class of single-input and single-output uncertain nonlinear systems with time-varying nonaffine nonlinear faults in strict-feedback form. In the design procedure, filtered signals are adopted to circumvent algebraic loop problems on implementing the usual controllers. By using fuzzy logic systems to approximate the unknown nonlinearity effects and changes in model dynamics due to faults, a fuzzy state observer is first presented to estimate the unmeasured states. Based on the online estimating information from the adaptive mechanism, an observer-based dynamic output feedback fault-tolerant controller is designed via the backstepping technique. It is shown that the stability and tracking performances of the closed-loop system can be achieved even in the presence of unknown nonlinear faults. In comparison with the existing approaches, the FTC scheme can handle the nonaffine nonlinear faults effectively. Finally, a simulation example is included to validate the advantages of the proposed approaches.

Dual-quaternion based fault-tolerant control for spacecraft formation flying with finite-time convergence

Study results of developing control system for spacecraft formation proximity operations between a target and a chaser are presented. In particular, a coupled model using dual quaternion is employed to describe the proximity problem of spacecraft formation, and a nonlinear adaptive fault-tolerant feedback control law is developed to enable the chaser spacecraft to track the position and attitude of the target even though its actuator occurs fault. Multiple-task capability of the proposed control system is further demonstrated in the presence of disturbances and parametric uncertainties as well. In addition, the practical finite-time stability feature of the closed-loop system is guaranteed theoretically under the designed control law. Numerical simulation of the proposed method is presented to demonstrate the advantages with respect to interference suppression, fast tracking, fault tolerant and practical finite-time stability.

A Combined Fault Tolerant and Predictive Control for Network-Based Industrial Processes

This paper investigates the tracking and optimization problems for a class of industrial processes by utilizing output feedback fault-tolerant control (FTC) and predictive compensation strategy. At device layer, the tracking problem for device layer subsystems which subject to random failures and random network-induced delays is investigated. These two different random processes are modeled as Markovian chains. Device layer controllers are designed to guarantee the tracking performance at $H_{\infty}$ disturbance attenuation level. At operation layer, a nonlinear model predictive control (NMPC) strategy is proposed to stabilize the upper operation layer system. Then by considering the effect of radial basis function (RBF) performance index and random packet dropout phenomena, a predictive compensator is designed to guarantee the input-to-state practical stability (ISpS) of the resulting system. In addition, networked flotation processes are considered in the simulation part, and the simulation results further demonstrate the effectiveness of the proposed method.

Adaptive Fault-Tolerant Congestion Control for Internet

Existing Internet congestion control algorithms did not consider any faults. This paper presents a state feedback fault-tolerant congestion control algorithm which is based on adaptive and robust H∞ approaches. Simulation result shows that the proposed algorithm has good performance.

Fault-Tolerant Control for LPV Systems Based on Fault Compensator

This 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.

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.

Impulsive robust fault-tolerant feedback control for chaotic Lur’e systems

This paper considers the problem of impulsive robust fault-tolerant feedback control for chaotic Lur’e systems. The sufficient condition of the uncertain Lur’e systems possessing integrity against actuator failures is given by using linear matrix inequalities (LMIs), and at the same time, the closed-loop system with impulsive effects is globally asymptotically stable, and it has robustness of parameter uncertainties. An example is given to illustrate obtained result.