Petri-net Controller for Pipe-line Transportation System
YuHao Fu, JiLiang Luo Senior Member, IEEE , WanZhen Lin, YiSheng Huang, and JianHong Ye
Abstract— As for a pipe-line plant subjected to complex log-
ical control specifications, an approach is proposed to generate
the control codes via Petri net such that the plant is run as
concurrently as possible. A PN model, called the plant net, is
designed to represent the whole process of a pipe-line system.
In this plant net, the tasks, including fluid transportation from
one tank to another and cleaning tank, are represented by
operational places, and level sensors in tanks are modeled by
labels assigned with transitions. Further, conflict structures are
used to describe the conflict relations among tasks due to the
shared valves and pipes. By introducing a priority order in the
transitions, an algorithm is presented to compute the control
commands for valves based on this plant net. A beer filtration
plant is taken as an example to illustrate the method.
I. INTRODUCTION
In a process industry, a pipe-line transportation system
is necessary. Due to a huge number of valves even in a
moderate plant, it is a challenge to optimally schedule and
control such a system by these valves. Besides, its control
requirements need to be modified once the transportation
tasks change, or some devices are damaged. This implies
we have to dynamically and quickly adjust or redesign the
controller accordingly. The traditional methods rely on trial
and error experiments to derive a concurrency control chart.
In turn, this chart is used to specify when and what control
events should be executed. However, this method is error-
prone, and costs much time. Evidently, it is valuable to
This work was supported in part by National Science Foundation of China
under Grant No. 61573158 and 61621002, Science and Technology Plan
Project of Fujian of China under Grant No. 2015H0026, Natural Science
Foundation of FuJian Province of China under Grant No. 2017J01117,
Science and Technology Planning Project of Fujian Province of China under
Grant No. 2018H01010060, and Science and Technology Planning Project
of Quanzhou City of China under Grant No. 2017T003 (Corresponding
author: JiLiang Luo)
Y. Fu is with College of Information Science and Engineering, Huaqiao
University, Xiamen 361021 China, and also with Fujian Engineering Re-
search Center of Motor Control and System Optimal Schedule, Xiamen
361021 China fuyuhao@outlook.com
J. Luo is with College of Information Science and Engineer-
ing, Huaqiao University, Xiamen 361021 China, and also with Fu-
jian Engineering Research Center of Motor Control and System
Optimal Schedule, Xiamen 361021 China jlluo@hqu.edu.cn,
luojiliang77@gmail.com
W. Lin is with College of Information Science and Engineering, Huaqiao
University, Xiamen 361021 China, and also with Fujian Engineering Re-
search Center of Motor Control and System Optimal Schedule, Xiamen
361021 China wzlin24@outlook.com
Y. Huang is with Department of Electrical Engineering, National Ilan
University, Taiwan huang.ccit@gmail.com
J. Ye is with College of Computer Science, Huaqiao University, Xia-
men 361021 China, and also with Fujian Engineering Research Center
of Motor Control and System Optimal Schedule, Xiamen 361021 China
Leafever@163.com
develop a reliable method to perform the logical control of
valves to efficiently run a pipe-line transportation system.
Since a pipe-line transportation system is driven by events
such as opening or closing valves, it can be modeled by Petri
nets (PNs) that are a powerful modeling tool for discrete
event systems (DES). The methods emerge to model and
control real DES plants such as a railway [1], chemical batch
plant [2-7], and manufacturing plant [8-10]. They are applied
to design programmable-logical-controllers via PN.
In order to flexibly and quickly compute the reliable
control codes for complex logical specifications, an approach
is proposed to design a Petri-net controller for a pipe-line
transportation system. First, a systemic modeling method is
presented to represent a pipe-line transportation system as a
labeled and timed Petri net, which is to be called the plant
net. In this plant net, tasks are abstracted as a pair of places,
where one is assigned a time delay and called an operational
place and the other is to represent the intermediate state
between two tasks, some places are designed to prevent
multiple operational places from being marked at the same
time if they are conflict due to the shared tank, pipe or
valve, and the level sensors are denoted as the labels assigned
to the corresponding transitions. Second, a priority order is
set for the transitions to resolve the conflicts of them, and
an algorithm is designed to compute the control commands
according to this plant net. A beer-filtration plant is taken as
a thorough example to illustrate the proposed method.
The rest of this paper consists of the following sections.
Section II presents basic concepts about timed and labeled
PN. Section III describes the problem of parallel control of
pipe-line transportation systems. In Section IV, a method
is proposed for modeling pipe-line transportation systems
by PN. In Section V, a method is obtained to compute
the control commands for manipulating valves. Section VI
concludes this work.
II. PRELIMINARIES
An ordinary PN structure is a four-tuple N =
(P, T, F, W ), where P (places) and T (transitions) are non-
empty, finite set of places and transition sets respectively,
F ⊆ (P × T ) ∪ (T × P ) is a collection of directed arcs
that connect to places and transitions; W : F → Z
+
is a
mapping that assigns each arc with a positive integer weight.
C
−
: P × T → Z and C
+
: T × P → Z are the forward and
backward associate matrices that define the weights of the
directed arcs from place to transition and from transition to
place, respectively. (The weight of 0 indicates that there is
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2018 5th International Conference on Control, Decision
and Information Technologies (CoDIT’18)
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April 10-13, 2018