The general fault-tolerant control method described in the article addresses actuator and sensor faults, which often affect highly automated systems. These faults correspond to a loss of actuator effectiveness or fault sensor measurements. After describing these faults, a fault estimation and compensation method was proposed. In addition to providing information to operators concerning the system operating conditions, the fault diagnosis module is especially important in fault-tolerant control systems where one needs to know exactly which element is faulty to react safely. The method's abilities to compensate for such faults are illustrated by applying it to a winding machine, which represents a subsystem of many industrial systems. The results show that once the fault is detected and isolated, it is easy to reduce its effect on the system, and process control is resumed with degraded performances close to nominal ones. Thus, stopping the system immediately can be avoided. However, the limits of this method are reached when there is the complete loss of an actuator. In this case, only a hardware redundancy is effective and could ensure performance reliability. The method proposed here assumes the availability of the state variables for measurement.

Fault-tolerant control in dynamic systems: application to a winding machine

In this paper, an adaptive Kalman filtering algorithm is developed for use to estimate the reduction of control effectiveness in a closed-loop setting. Control effectiveness factors are used to quantify faults entering control systems through actuators. A set of covariance-dependent forgetting factors is introduced into the filtering algorithm. As a result, the change in the control effectiveness is accentuated to help achieve a more accurate estimate more rapidly. A weighted sum-squared bias estimate is defined for the change detection. The state estimate is fed back to achieve the steady-state regulation, while the control effectiveness estimate is used for the on-line tuning of the control law. A stability analysis is performed for the adaptive regulator. Copyright © 2000 John Wiley & Sons, Ltd.

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Detection, estimation, and accommodation of loss of control effectiveness

This article presents a historical overview of research in reconfigurable flight control. For the purpose of this article, the term ‘reconfigurable flight control’ is used to refer to softw...

https://journals.sagepub.com/doi/pdf/10.1243/095441005X30379

Historical Overview of Research in Reconfigurable Flight Control

Fault-tolerant control strategy for actuator faults using LPV techniques: Application to a two degree of freedom helicopterIn this paper, a Fault Tolerant Control FTC strategy for Linear Parameter Varying LPV systems that can be used in the case of actuator faults is proposed. The idea of this FTC method is to adapt the faulty plant instead of adapting the controller to the faulty plant. This approach can be seen as a kind of virtual actuator. An integrated FTC design procedure for the fault identification and fault-tolerant control schemes using LPV techniques is provided as well. Fault identification is based on the use of an Unknown Input Observer UIO. The FTC controller is implemented as a state feedback controller and designed using polytopic LPV techniques and Linear Matrix Inequality LMI regions in such a way as to guarantee the closed-loop behavior in terms of several LMI constraints. To assess the performance of the proposed approach, a two degree of freedom helicopter is used.

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Fault-tolerant control strategy for actuator faults using LPV techniques

This paper investigates the problem of robust fault detection observer design for nonlinear Takagi-Sugeno models with unmeasurable premise variables subject to sensor faults and unknown bounded disturbance. The main idea is to synthesize a robust fault detection observer by means of a mixed H =H1 performance index. The considered observer is used to estimate jointly states and faults. Using the technique of descriptor system representation, we proposed a new less-conservative approach in term of a linear matrix inequality (LMI) by considering the sensor fault as an auxiliary state variable. A solution of the problem is obtained by using an iterative LMI procedure.

/pdf/multi-objective-h-h-fault-detection-observer-design-for-o1lkgmbu6a.pdf

Multi-objective H − ∕ H ∞ fault detection observer design for Takagi–Sugeno fuzzy systems with unmeasurable premise variables: descriptor approach

In this paper, the robust fault-tolerant control problem is formulated in an linear matrix inequality (LMI) setting, in which satisfactory performance and guarantees stability robustness are introduced. To achieve both performance and stability robustness, a multiobjective approach is used to establish a matrix inequality formulation for fault-tolerant control system design which is based on the assumption that both fault effect factors and uncertainties can be of linear-fractional-transformation parameter dependence. An example of flight control system is used to demonstrates the design technique presented in this paper.

Z. Chen

Papers

An LMI approach to fault-tolerant control of uncertain systems