Nonlinear Dyn (2015) 80:51–58
DOI 10.1007/s11071-014-1850-y
ORIGINAL PAPER
Adaptive sliding-mode control for fractional-order
uncertain linear systems with nonlinear disturbances
Liping Chen · Ranchao Wu · Yigang He ·
Yi Chai
Received: 2 July 2014 / Accepted: 4 December 2014 / Published online: 16 December 2014
© Springer Science+Business Media Dordrecht 2014
Abstract The problem of designing a sliding-mode
controller for a class of fractional-order uncertain linear
perturbed systems with Caputo derivative is addressed
in this paper. Sufficient conditions for the existence
of sliding surfaces guaranteeing the asymptotic sta-
bility of the reduced-order sliding-mode dynamics are
obtained in terms of linear matrix inequalities, based on
which and stability theory of fractional-order nonlinear
systems; the corresponding reaching motion controller
is proposed, and the reaching time is also obtained.
Moreover, the upper bounds of the nonlinear uncer-
tainties are not required to be known in advance, which
can be tuned by the designed adaptive law. Mean-
while, some problems for the sliding-mode controller
for fractional-order systems in existing literatures are
pointed out. A numerical example is presented to
demonstrate the validity and feasibility of the obtained
results.
L. Chen (
B
) · Y. H e
School of Electrical Engineering and Automation, Hefei
University of Technology, Hefei 230009, China
e-mail:lip_chen@hfut.edu.cn; lip_chenhut@126.com
R. Wu
School of Mathematics, Anhui University, Hefei 230039,
China
Y. C h a i
School of Automation, Chongqing University,
Chongqing 400044, China
Keywords Fractional-order systems · Sliding-mode
control · Linear matrix inequalities · Sliding-mode
surface
1 Introduction
As a branch of mathematics, fractional calculus deals
with derivatives and integrals of order that may be real
or complex. The essential difference between models
with the fractional-order derivative and the integer-
order derivative lies in the following two aspects. First,
the integer-order derivative indicates a variation or
certain attribute at particular time for a physical or
mechanical process, while the fractional-order deriva-
tive is concerned with the whole time domain. Second,
the integer-order derivative describes the local proper-
ties of a certain position for a physical process, while
the fractional-order one is related to the whole space.
Therefore, compared with traditional integer-order cal-
culus, fractional calculus provides a powerful tool for
the description of memory and hereditary effects in
various substances, as well as for modeling dynami-
cal processes, for instance, electrochemical processes,
flexible structures, biological systems, finance systems,
the dielectric polarization, electromagnetic waves, vis-
coelastic systems, diffusion processes, heat flowing
phenomena and so on. For further applications of
fractional-order systems to the engineering area, please
refer to [1–7].
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