Leader-follower Flocking for Cooperative Control of
Multiple Motors
Han Wu, Changfan Zhang*, Mangang Niu, Yuanyuan Xiao
College of Electrical and Information Engineering Hunan University of Technology
Zhuzhou, Hunan, 412007, China
zhangchangfan@263.net
Abstract—For the purpose of improving the multi-axis syn-
chronous control precision for shaft-less drive printing press,
this paper presents a leader-follower mode based flocking control
method. First, based on flocking intelligence theory, as well as the
use of graph theory and matrix theory, the interaction relation
of each agent is described and the distributed synchronous
control strategy is proposed. Next, PID controllers are designed
to make tracking error and synchronous coordinating error
converge to zero, respectively. Specifically, by using an off-
line parameter optimization method, the system has received a
better synchronous performance. Finally, the simulation results
demonstrate the effectiveness and superiority of the proposed
methodology.
Keywords—flocking, leader-follower, parameter optimization,
synchronous control, shaft-less drive
I. INTRODUCTION
With the rapid development of productivity, more and more
researchers concentrate on the design of synchronization strat-
egy optimization in order to reduce synchronous error among
multi-axis. Presently, how to find a synchronization way with
better performance for high-speed shaft-less drive has become
a topic for in-depth study among control research communities.
The conventional synchronous control approaches are main-
ly include master-slave control, electronic virtual line shafting
control, cross coupling control and etc [1]. Existing literatures
demonstrate that multi-axis synchronous control of printing
press is mainly realized by electronic virtual line shafting
control [2-4]. However, it cannot make sure a minimum
synchronous error of the output among shafts when there exist
a disturbance in system.
Flocking control is emerging from the collective behavior
and self-organization phenomenon of living beings in nature
[5-6]. Recent work has explored how flocking control can be
used in multiple robots, aircrafts and other intelligence field,
in addition, excellent overall synchronization effect has been
obtained [7]. The formalized definition of flocking is first put
forward in [8]. Some further studies have contributed to the
basic flocking control law based on agent [9]. In the pres-
ence of these theoretical basis, the Leader-Follower and other
flocking control methods are successively proposed afterwards
[10].Due to its simplicity and expand ability, Leader-Follower
*Author for correspondence.
based flocking control method has been widely used in the
formation control of multiple mobile agents [11]. In [12], it
analyzes several kinds of virtual leaders mode based flocking
motion in detail. All agents being informed and the virtual
leader traveling at a constant velocity are the two critical
assumptions seen in the recent literature.Other works propose
a flocking algorithm based on one single virtual leader [13].
Further expansion and algorithm improvement is carried out
in the absence of the above two assumptions[14]; In addition,
flocking algorithm based on multiple virtual leaders is another
new progress [15].These papers argue that flocking control
method has presented excellent synchronous performance in
cooperative control. However, its application in shaft-less drive
printing press has not been opened to public.
Owing to its excellent performance on synchronization, it
is reasonable for us to introduce flocking control into the
synchronous control of shaft-less drive printing press. Hence,
this paper presents a new approach to improve multi-axis syn-
chronous performance. A flocking control strategy is proposed
based on leader-follower method. This control method not
only has the advantages of virtual line shafting control but
also introduces flocking intelligence theory, so the synchronous
performance of multi-motor can be significantly improved.
This paper is organized as follows. Section II describes the
Multi-motor flocking system and proposes flocking control
strategy. Section III establishes the model of DC motor and
Multi-motor flocking system, respectively. And designs PID
controllers using an off-line parameter optimization method.
Section IV presents the simulink results. Finally, Section V
makes some concluding remarks.
II. MULTI-MOTOR FLOCKING AND DISTRIB UTED
SYNCHRONOUS CONTROL STRATEGY
This section introduces the concept of flocking for multi-
motor synchronous control. Based on graph theory and matrix
theory, the description of interaction relation among motors
and the design of distributed synchronous control strategy are
demonstrated intuitively.
A. Leader-follower based multi-motor flocking