Automatica 52 (2015) 242–247
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Automatica
journal homepage: www.elsevier.com/locate/automatica
Brief paper
Stabilization of neutral time-delay systems with actuator saturation
via auxiliary time-delay feedback
✩
Yonggang Chen
a
, Shumin Fei
b
, Yongmin Li
c
a
School of Mathematical Sciences, Henan Institute of Science and Technology, Xinxiang 453003, PR China
b
Key Laboratory of Measurement and Control of CSE (Ministry of Education), School of Automation, Southeast University, Nanjing 210096, PR China
c
School of Science, Huzhou Teachers College, Huzhou 313000, PR China
a r t i c l e i n f o
Article history:
Received 9 December 2013
Received in revised form
17 September 2014
Accepted 9 November 2014
Available online 26 December 2014
Keywords:
Stabilization
Neutral systems
Actuator saturation
Auxiliary time-delay feedback
a b s t r a c t
This paper investigates the stabilization problem for neutral time-delay systems with actuator saturation.
Different from the existing techniques, the auxiliary time-delay feedback is introduced for the first
time in this paper. Based on such a technique, the saturation nonlinearity is represented as the convex
combination of state feedback and auxiliary time-delay feedback. By employing free-weighting matrix
technique and Jensen integral inequalities, and performing the accurate estimation of the lower bounds
of L–K functionals, the improved delay-dependent local stabilization conditions are proposed in terms of
linear matrix inequalities (LMIs). Numerical examples illustrate the reduced conservatism of the proposed
conditions in this paper.
© 2014 Elsevier Ltd. All rights reserved.
1. Introduction
Time-delays are frequently encountered in various practical
systems, such as chemical engineering systems, biological sys-
tems and manufacturing processes (Gu, Kharitonov, & Chen, 2003).
There are two types of time-delay systems, i.e., retarded type and
neutral type. The retarded type contains delays only in its states,
while the neutral type contains delays in both its states and its
derivatives of the states. On the other hand, it is well recognized
that LMI-based approaches are more convenient for solving cor-
responding synthesis problems, and delay-dependent results are
generally less conservative than delay-independent ones espe-
cially when the size of delay is small (Xu & Jam, 2008). During
the past two decades, several important techniques have been pro-
posed to obtain LMI-based delay-dependent analysis and synthe-
sis conditions for time-delay systems, see, e.g., Chen and Zheng
(2007), Fridman (2001), Han (2009), He, Wang, Lin, and Wu (2005);
✩
This work was supported by the National Natural Science Foundations of
China under Grants 61304061, 61273119, 61174076 and 61374086. This work
was also partly supported by the Natural Science Foundation of Henan Institute of
Science and Technology (201319). The material in this paper was not presented at
any conference. This paper was recommended for publication in revised form by
Associate Editor Fen Wu under the direction of Editor Roberto Tempo.
E-mail addresses: happycygzmd@tom.com (Y. Chen), smfei@seu.edu.cn (S. Fei),
ymlwww@163.com (Y. Li).
He, Wang, Xie, and Lin (2007); He, Wu, She, and Liu (2004), Li, Jing,
and Karimi (2014), Qian, Liu, and Fei (2012) and Sun, Liu, and Chen
(2009).
In many practical control applications, actuator saturation is
often inevitable, and its existence may deteriorate the perfor-
mance of a control system and even cause the instability of closed-
loop system. Therefore, considerable attention has been devoted
to linear systems subject to saturating controllers during the past
decades, see e.g., Alamo, Cepeda, and Limon (2005), Gomes da
Silva and Tarbouriech (2005); Hu and Lin (2001), Hu, Lin, and Chen
(2002), Lin (1998), Tarbouriech, Garcia, Gomes da Silva, and Quein-
nec (2011), Zhou (2013) and Zhou, Lin, and Duan (2008). Gen-
erally speaking, the current research can be classified into two
categories according to whether the open-loop poles are located on
the closed left-half plane, i.e., global/semi-global stabilization, and
local stabilization and anti-windup design. For the local stabiliza-
tion and anti-windup design, two dominant approaches are pro-
posed to deal with the saturation nonlinearity, one is the polytopic
models (Alamo et al., 2005; Hu & Lin, 2001; Hu et al., 2002; Zhou,
2013) and the other is the generalized sector condition (Gomes da
Silva & Tarbouriech, 2005). In particular, it is worth mentioning
that the saturation representation proposed in Alamo et al. (2005)
and Tarbouriech et al. (2011) with the compact notation proposed
in Zhou (2013) contains more slack variables, and thus is less con-
servative than that in Hu and Lin (2001) and Hu et al. (2002) for the
multiple input systems.
http://dx.doi.org/10.1016/j.automatica.2014.11.015
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