Neurocomputing 405 (2020) 96–102
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Neurocomputing
journal homepage: www.elsevier.com/locate/neucom
Leader-following bipartite consensus of multiple uncertain
Euler-Lagrange systems over signed switching digraphs
Dong Liang, Jie Huang
∗
Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, N.T., Hong Kong
a r t i c l e i n f o
Article history:
Received 8 January 2020
Revised 12 March 2020
Accepted 6 April 2020
Available online 11 May 2020
Communicated by Dr. Derui Ding
Keywords:
Bipartite consensus
Distributed observer
Learning control
Multiple Euler-Lagrange systems
Signed switching networks
a b s t r a c t
In this paper, we investigate the leader-following bipartite consensus problem of multiple uncertain Euler-
Lagrange (EL) systems over signed switching networks. We first extend the distributed observer for a
linear leader system over signed communication networks from the static case to the jointly connected
switching case. Based on such a distributed observer and the certainty equivalence principle, we further
show that, under the assumptions that the signed switching network is structurally balanced and jointly
connected, the leader-following bipartite consensus problem of multiple uncertain EL systems over signed
switching networks is solvable by a class of distributed adaptive control law. Our result will then be
applied to the leader-following bipartite consensus problem of a group of two-link robot manipulators.
©2020 Elsevier B.V. All rights reserved.
1.
Introduction
Over the past few years, the distributed control of multi-agent
systems over signed graphs has received considerable attention. In
practice, a signed digraph can represent, say, allied/adversary re-
lationships such as two parties in politics since cooperation and
competition often coexist, trade war between countries or opin-
ion dynamics in trust-mistrust social networks [22] . A fundamen-
tal problem in the distributed control of multi-agent systems over
signed graphs is the so-called bipartite consensus, which is to de-
sign a distributed control law to achieve modulus consensus for
each agent with antagonistic interactions [1] .
Early work on the bipartite consensus focused on multiple
single-integrator systems. For example, in [1] , Altafini showed that
the bipartite consensus for multiple single-integrator systems can
be achieved if and only if the signed graph is structurally bal-
anced and connected. The result in [1] was then extended to the
general linear multi-agent systems [6,23,24,26] . Like the consen-
sus problem over unsigned graphs, the bipartite consensus can
also be classified into leaderless case [1] and leader-following
case [11,13,20,21] . The bipartite tracking problem was studied in
[11] with a scalar leader system, and in [6,18,21] with a high-order
leader system. In [9] , the robust bipartite output regulation for a
∗
Corresponding author.
E-mail addresses: dliang@mae.cuhk.edu.hk (D. Liang), jhuang@mae.cuhk.edu.hk
(J. Huang).
class of general linear systems was studied, which aims to achieve
asymptotic modulus tracking in the presence of a class of distur-
bances. Almost all the publications mentioned above assumed that
the signed graphs were static. Recently, the distributed control of
multi-agent systems over signed switching graphs were consid-
ered in some papers. For example, the output bipartite consen-
sus of heterogeneous linear multi-agent systems was investigated
in [19] by a distributed dynamic output feedback control law. The
bipartite synchronization of a class of nonlinear systems satisfying
the one-sided Lipschitz condition over signed switching networks
was studied in [25] . Other relevant work on bipartite consensus
over signed switching topologies can be found in [7] .
EL systems are an important class of nonlinear systems that can
model robots, spacecraft systems, etc [8,10] . The cooperative con-
trol problems of multiple EL systems over unsigned communica-
tion networks have been thoroughly studied in quite a few papers
[3,4,14] . In particular, Ref. [3] solved the leader-following consensus
problem of multiple EL systems over jointly connected switching
networks via a distributed observer approach. More recently, the
study of the cooperative control problems of multiple EL systems
has been extended to the signed communication networks. For ex-
ample, Ref. [5] considered the swarming behaviors of multiple EL
systems with uncertain parameters over signed static communica-
tion networks.
In this paper, we will further study the leader-following bipar-
tite consensus problem of multiple EL systems over signed switch-
ing communication networks. Compared with [5] , our paper offers
at least three new features. First, our digraph is a signed switching
https://doi.org/10.1016/j.neucom.2020.04.050
0925-2312/© 2020 Elsevier B.V. All rights reserved.