Wyniki wyszukiwania - BazTech

1

H−/H∞ fault detection observer design for a polytopic LPV system using the relative degree

Zhou M., Rodrigues M., Shen Y., Theilliol D.

International Journal of Applied Mathematics and Computer Science

|

2018

|

Vol. 28, no. 1

83--95

EN

This paper proposes an H−/H∞ fault detection observer method by using generalized output for a class of polytopic linear parameter-varying (LPV) systems. As the main contribution, with the aid of the relative degree of output, a new output vector is generated by gathering the original output and its time derivative, and it is feasible to consider H− actuator fault sensitivity in the entire frequency for the new system. In order to improve actuator and sensor fault sensitivity as well as guarantee robustness against disturbances, simultaneously, an H−/H∞ fault detection observer is designed for the new LPV polytopic system. Besides, the design conditions of the proposed observer are transformed into an optimization problem by solving a set of linear matrix inequalities (LMIs). Numerical simulations are provided to illustrate the effectiveness of the proposed method.

2

An active fault-tolerant control framework against actuator stuck failures under input saturations

Qi X., Theilliol D., He Y., Han J.

International Journal of Applied Mathematics and Computer Science

|

2017

|

Vol. 27, no. 4

749--761

EN

In this paper, a control framework including active fault-tolerant control (FTC) and reference redesign is developed subject to actuator stuck failures under input saturations. FTC synthesis and reference redesign approaches are proposed to guarantee post-fault system safety and reference reachability. Then, these features are analyzed under both actuator stuck failures and constraints before fault-tolerant controller switches. As the main contribution, actuator stuck failures and constraints are unified so that they can be easily considered simultaneously. By means of transforming stuck failures into actuator constraints, the post-fault system can be regarded as an equivalent system with only asymmetrical actuator constraints. Thus, methods against actuator saturations can be used to guarantee regional stability and produce the stability region. Based on this region, stuck compensation is analyzed. Specifically, an unstable open-loop system is considered, which is more challenging. Furthermore, the method is extended to a set-point tracking problem where the reachability of the original reference can be evaluated. Then, a new optimal reference will be computed for the post-fault system if the original one is unreachable. Finally, simulation examples are shown to illustrate the theoretical results.

3

Robust sensor fault estimation for descriptor-LPV systems with unmeasurable gain scheduling functions: Application to an anaerobic bioreactor

López-Estrada F. R., Ponsart J. C., Theilliol D., Astorga-Zaragoza C. M., Camas-Anzueto J. L.

International Journal of Applied Mathematics and Computer Science

|

2015

|

Vol. 25, no. 2

233--244

EN

This paper addresses the design of a state estimation and sensor fault detection, isolation and fault estimation observer for descriptor-linear parameter varying (D-LPV) systems. In contrast to where the scheduling functions depend on some measurable time varying state, the proposed method considers the scheduling function depending on an unmeasurable state vector. In order to isolate, detect and estimate sensor faults, an augmented system is constructed by considering faults to be auxiliary state vectors. An unknown input LPV observer is designed to estimate simultaneously system states and faults. Sufficient conditions to guarantee stability and robustness against the uncertainty provided by the unmeasurable scheduling functions and the influence of disturbances are synthesized via a linear matrix inequality (LMI) formulation by considering H∞ and Lyapunov approaches. The performances of the proposed method are illustrated through the application to an anaerobic bioreactor model.

4

Reconfigurable control design with integration of a reference governor and reliability indicators

Weber P., Boussaid B., Khelassi A., Theilliol D., Aubrun C.

International Journal of Applied Mathematics and Computer Science

|

2012

|

Vol. 22, no. 1

139-148

EN

A new approach to manage actuator redundancy in the presence of faults is proposed based on reliability indicators and a reference governor. The aim is to preserve the health of the actuators and the availability of the system both in the nominal behavior and in the presence of actuator faults. The use of reference governor control allocation is a solution to distribute the control efforts among a redundant set of actuators. In a degraded situation, a reconfigured control allocation strategy is proposed based on on-line re-estimation of the actuator reliability. A benefit of incorporating reliability indicators into over-actuated control system design is the smart management of the redundant actuators and improvement of the system safety. Moreover, when the fault is severe, an adaptation approach using the reference governor is proposed. The reference governor unit is a reference-offset governor based on a discrete-time predictive control strategy. The idea is to modify the reference according to the system constraints, which become stricter after the occurrence of an actuator fault. The proposed approach is illustrated with a flight control application.

5

Reconfigurability analysis for reliable fault-tolerant control desig

Khelassi A., Theilliol D., Weber P.

International Journal of Applied Mathematics and Computer Science

|

2011

|

Vol. 21, no 3

431-439

EN

In this paper the integration of reliability evaluation in reconfigurability analysis of a fault-tolerant control system is considered. The aim of this work is to contribute to reliable fault-tolerant control design. The admissibility of control reconfigurability is analyzed with respect to reliability requirements. This analysis shows the relationship between reliability and control reconfigurability defined generally through Gramian controllability. An admissible solution for reconfigurability is proposed according to reliability evaluation based on energy consumption under degraded functional conditions. The proposed study is illustrated with a flight control application.

6

Fault tolerance in networked control systems under intermittent observations

Georges J. P., Theilliol D., Cocquempot V., Ponsart J. C., Aubrun C.

International Journal of Applied Mathematics and Computer Science

|

2011

|

Vol. 21, no 4

639-648

EN

This paper presents an approach to fault tolerant control based on the sensor masking principle in the case of wireless networked control systems. With wireless transmission, packet losses act as sensor faults. In the presence of such faults, the faulty measurements corrupt directly the behaviour of closed-loop systems. Since the controller aims at cancelling the error between the measurement and its reference input, the real outputs will, in such a networked control system, deviate from the desired value and may drive the system to its physical limitations or even to instability. The proposed method facilitates fault compensation based on an interacting multiple model approach developed in the framework of channel errors or network congestion equivalent to multiple sensors failures. The interacting multiple model method involved in a networked control system provides simultaneously detection and isolation of on-line packet losses, and also performs a suitable state estimation. Based on particular knowledge of packet losses, sensor fault-tolerant controls are obtained by computing a new control law using fault-free estimation of the faulty element to avoid intermittent observations that might develop into failures and to minimize the effects on system performance and safety.

7

Actuator fault tolerant control design based on a reconfigurable reference input

Theilliol D., Join C., Zhang Y.

International Journal of Applied Mathematics and Computer Science

|

2008

|

Vol. 18, no 4

553-560

EN

The 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.

8

Fault tolerant control design for polytopic LPV systems

Rodrigues M., Theilliol D., Aberkane S., Sauter D.

International Journal of Applied Mathematics and Computer Science

|

2007

|

Vol. 17, no 1

27-37

EN

This paper deals with a Fault Tolerant Control (FTC) strategy for polytopic Linear Parameter Varying (LPV) systems. The main contribution consists in the design of a Static Output Feedback (SOF) dedicated to such systems in the presence of multiple actuator faults/failures. The controllers are synthesized through Linear Matrix Inequalities (LMIs) in both faultfree and faulty cases in order to preserve the system closed-loop stability. Hence, this paper provides a new sufficient (but not necessary) condition for the solvability of the stabilizing output feedback control problem. An example illustrates the effectiveness and performances of the proposed FTC method.