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Published in IET Control Theory and Applications
Received on 8th October 2011
Revised on 25th February 2012
doi: 10.1049/iet-cta.2011.0599
ISSN 1751-8644
Brief Paper
Robust adaptive fault-tolerant control for uncertain
linear systems with actuator failures
X.-J. Li
1
G.-H.Yang
2,∗
1
College of Sciences, Northeastern University, Shenyang, Liaoning 110004, People’s Republic of China
2
College of Information Science and Engineering, Northeastern University, Shenyang, Liaoning 110004,
People’s Republic of China
∗
State Key Laboratory of Synthetical Automation for Process Industries, Northeastern University, Shenyang 110004,
People’s Republic of China
E-mail: yangguanghong@ise.neu.edu.cn
Abstract: This study is concerned with the robust adaptive fault-tolerant compensation control problem for linear systems
with parameter uncertainty, disturbance and actuator faults including outage, loss of effectiveness and stuck. It is assumed
that the lower and upper bounds of actuator efficiency factor, the upper bounds of disturbance and the unparametrisable time-
varying stuck fault, are unknown. Then, according to the information from the adaptive mechanism, the effect of actuator
fault, exogenous disturbance and parameter uncertainty can be eliminated completely by designing adaptive state feedback
controller. Furthermore, it is shown that the solutions of the resulting adaptive closed-loop system are uniformly bounded,
the states converge asymptotically to zero. Finally, two examples are given to illustrate the effectiveness and applicability of
the proposed design method.
1 Introduction
Actuator failures can cause severe performance deterioration
of control systems, or even system instability leading
to catastrophic accidents. For example, if an actuator is
suddenly stuck and can no longer deflect a certain control
surface in an aircraft, it may end with catastrophic events.
So the research on accommodating actuator failures and
maintaining acceptable system performance has received
considerable attention from the control engineers in the past
couple of decades. The methods and techniques that were
developed for this can be broadly classified into two types:
passive approach and active approach.
Typical passive approaches mainly based on robust
control theory, use fixed controllers throughout fault-free
and faulty cases, for example [1–6]. It is simple to design
and implement but cannot guarantee system stability and
satisfactory performance if any fault outside the predefined
faulty set occurs. In contrast to the passive solution, a
fault-tolerant control system based on active approaches can
compensate for faults either by selecting a precomputed
control law or by synthesising a new control strategy
online. Then the stability as well as the acceptable
performance of the system can be maintained. A lot
of active approaches have been proposed such as fault
diagnosis-based approaches [7–11], sliding mode control-
based designs [12], learning-based approaches [13, 14]
and multiple-model designs [15, 16]. Recently, adaptive
actuator failure compensation control schemes have also
been developed for compensation of unknown actuator
failures [17–26].
In [17–19], the type of faults under consideration is
loss of actuator effectiveness, and adaptive fault-tolerant
controller design approaches are developed by estimating
the efficiency factor online. For actuator stuck faults, the
authors of [20–22] provide direct adaptive fault-tolerant
control approaches, and Chen and Jiang [23] design adaptive
fault-tolerant control scheme by introducing an iterative
learning observer. Furthermore, a more general actuator fault
model simultaneously including outage, loss of effectiveness
and stuck is given in [24–26]. In these works, Boskovic
and Mehra [24] and Wang and Wen [25] investigate the
non-linear systems with ‘constant stuck fault’. Jin and
Yang [26] are concerned with the linear systems subject
to ‘unparametrisable time-varying stuck fault’, but the
knowledge of lower and upper bounds of actuator efficiency
factor is needed.
On the other hand, the robustness of adaptive failure
compensation designs with respect to system parameter
uncertainty and external disturbance is also an important
issue. The authors of [17, 20–25] have not considered any
disturbance or parameter uncertainty within the systems. In
[18, 19], adaptive H
∞
fault-tolerant controller is designed to
1544 IET Control Theory Appl., 2012, Vol. 6, Iss. 10, pp. 1544–1551
© The Institution of Engineering and Technology 2012 doi: 10.1049/iet-cta.2011.0599