Actuator Fault Tolerant Control Research Articles

Bank of Virtual Actuators for Fault Tolerant Control

AbstractWe propose an actuator fault tolerant control scheme based on a bank of virtual actuators (VA), with the novel feature that the virtual actuators implicitly integrate both fault detection and isolation (FDI) and controller reconfiguration (CR) tasks. The bank of VAs operates in closed-loop with an observer-based tracking controller designed for a nominal (fault free) model of the plant. We consider abrupt actuator faults ranging over a finite cover. Each VA is designed to operate appropriately in combination with the nominal controller to achieve correct CR for a particular fault situation in the considered range. A switching rule that engages the suitable VA from the bank is based on sets defined for measurable residual signals constructed directly from the virtual actuators signals. The overall scheme is shown to guarantee closed-loop boundedness and setpoint tracking under all considered fault situations. The method is applied to an example of aircraft lateral control.

Robust MPC multicontroller design for actuator fault tolerance of constrained systems

AbstractIn this paper, we present a robust actuator fault-tolerant control strategy for constrained linear systems, in the presence of bounded state and output disturbances. The scheme is based on a bank of state estimators which match different fault situations that can occur in the system. A fault detection and isolation (FDI) unit verifies that suitable residual variables lie inside pre-computed sets and selects the estimate that matches the current plant behaviour. A bank of robustly stabilising tube-based MPC control laws is designed, each associated to a fault scenario and the appropriate controller is selected among them using the information provided by the FDI module. By means of “tubes” of trajectories, we ensure robust closed-loop exponential stability of the constrained system and good performance in the fault-free case and under the occurrence of abrupt actuator faults.

Observer-based Fault Tolerant Sliding Mode Control for Remotely Operated Vehicles

Abstract This paper proposes an actuator fault-tolerant control scheme designed for a class of nonlinear systems, and then applied to an underwater Remotely Operated Vehicle (ROV) used for inspection purposes. Fault detection is achieved using a Variable Structure System (VSS) observer, while a sliding-mode based approach has been used both for fault isolation and ROV control, after the application of an input decoupling nonlinear state transformation to the ROV model. Finally, control reconfiguration is performed exploiting the inherent redundancy of actuators. An extensive simulation study has been also performed, supporting the effectiveness of the proposed approach.

Actuator Failure Tolerant Control Design for Underwater Remotely Operated Vehicles

This paper proposes an actuator fault-tolerant control scheme, composed of the usual modules performing detection, isolation, accommodation, designed for a class of nonlinear systems, and then applied to an underwater remotely operated vehicle (ROV) used for inspection purposes. Detection is in charge of a residual generation module, while a sliding-mode based approach has been used both for ROV control and fault detection, after the application of an input decoupling nonlinear state transformation to the ROV model. Finally, control reconfiguration is performed exploiting the inherent redundancy of actuators. An extensive simulation study has been also performed, supporting the effectiveness of the proposed approach.

Actuator fault-tolerant control for discrete systems with strong uncertainties

In this paper, a reliable control method is first proposed for discrete systems with strong uncertainties. Actuator fault compensation is also investigated based on state feedback controller. The reliable control approach uses analytical redundancy and does not need duplicated actuators. Fault compensation controller is designed using accommodation mechanism which compensates the fault effects. The closed-loop stability is established based on Lyapunov's sense. The novelty of this paper is in controller design part. This reliable control approach is applied to three-tank system. The fault compensation method is applied to winding machine in continuous annealing process systems. Applications of the proposed design indicate that the method is effective for three-tank system and continuous annealing process systems.

Actuator Fault-tolerant control for vehicle dynamics

—This paper presents Fault-Tolerant Control (FTC) architecture for vehicle dynamics represented by an LPV (Linear Parameter Varying) model with actuator failures. The type of faults considered in this work is total or partial loss of actuator effectiveness. This method does not need any on-line fault estimation, detection or identification mechanism. The proposed approach is applied to the actuator fault tolerant control of vehicle dynamics. It is based on the resolution of LMIs, using the concept of DC-stability and involving PDLM (Parameter-Dependent Lyapunov Matrix). In order to highlight the performance of the proposed control algorithm, numerical simulations are performed.

Invariant set approach to actuator fault tolerant control

We present a new actuator fault-tolerant control strategy based on the separation of sets that characterise healthy system operation from sets that characterise faulty operation. The new scheme is an extension of a similar strategy recently proposed by the authors. In the present paper we propose a new criterion for fault detection and isolation that leads to less conservative conditions for fault tolerant closed-loop stability. These new conditions employ discrete-time models for the plant, reference system and observers and allow for quicker fault detection and consequent reconfiguration of the controller.

Actuator Fault Tolerant Control Design Based on a Reconfigurable Reference Input

Actuator Fault Tolerant Control Design Based on a Reconfigurable Reference InputThe prospective work reported in this paper explores a new approach to enhance the performance of an active fault tolerant control system. The proposed technique is based on a modified recovery/trajectory control system in which a reconfigurable reference input is considered when performance degradation occurs in the system due to faults in actuator dynamics. An added value of this work is to reduce the energy spent to achieve the desired closed-loop performance. This work is justified by the need of maintaining a reliable system in a dynamical way in order to achieve a mission by an autonomous system, e.g., a launcher, a satellite, a submarine, etc. The effectiveness is illustrated using a three-tank system for slowly varying reference inputs corrupted by actuators faults.

Actuator Fault-Tolerant Control based on Invariant Set Separation

Abstract In this paper an actuator fault-tolerant control (FTC) strategy based on invariant set computation is presented. The proposed scheme is based on a bank of observers which match different fault situations that can occur in the plant. Each of these observers produces an estimation error with a distinctive behavior when the observer matches the current fault situation in the plant. With the information of the estimation errors from each of the considered observers, a fault diagnosis and isolation (FDI) module is able to reconfigure the control loop by selecting the appropriate stabilising controller from a bank of precomputed control laws, each of them related to one of the considered fault models. The decision criteria of the FDI is based on the computation of invariant sets of the estimation errors for each fault scenario and for each control configuration. Conditions for the design of the FDI module and for fault-tolerant closed-loop stability are given, and the effectiveness of the approach is illustrated with an example.