HOLONIC PRODUCTION PROCESS: A MODEL OF COMPLEX,
PRECISE, AND GLOBAL SYSTEMS
Edgar Chacon, Isabel Besembel, Dulce Rivero
Universidad de Los Andes, Facultad de Ingeniería, Escuela de Sistemas, Departamento de Computación, Mérida, 5101
Juan Cardillo
Universidad de Los Andes, Facultad de Ingeniería, Escuela de Sistemas, Departamento de Sistemas de Control, Mérida,
Keywords: Holon, Holonic Production Units, Complex Systems Modelling, Discrete Event Dynamic Systems,
Continuous Production Process, Value Chain.
Abstract: Nowadays, it is necessary to have a complete description of the production process in order to plan,
program, control, and supervise the production process. It is hard to obtain this description due to the
existence of two contradictory points of views. First, the precision implicated in the construction of total and
complete models, and on the other hand, the need of having a global vision associated with the different
views of the process. These views normally show three important aspects: the structural organization of the
model, the dynamism between the main components, and the distinct temporal scales and levels, where are
taken the main decisions. The holonic approach (Erikson,2004) has been used to manage this complexity, in
order to have an abstraction that permit the integration of the mentioned points of views. In this paper we
propose, a structure for continuous production process based on holonic approach in order to obtain a global
vision and global model less complex of the production process.
1 INTRODUCTION
Nowadays, enterprises can be established in a virtual
manner building a dynamic network of enterprises in
order to obtain a determined product, in a moment
due. The high enterprises’ performance is due to the
establishment of precise objectives for a determined
configuration of the network.
The virtual enterprise, composed in this way
follows a set of production agreements, in order to
fulfil objectives by trying to diminish the production
cost of the product, in a production offer. This
virtual enterprise may be composed by a set of
enterprises or a set of unit of the enterprise itself.
The production agreements implicate the
establishment of a logistic, quantities, and qualities
of products and sub-products, and synchronization
points (E. Chacon,1998), (E. Chacon, 2004), (Juan
Cardillo, 2005).
The negotiation is obtained following the
existing common knowledge, for which it is
necessary to have the following:
A description language of the production
methods
Protocols for the acceptation of missions
among the enterprise participants,
following each one of production
capacities under a production method of
high level.
The enterprises participating in a negotiation
know the information services that offer each
enterprise by means of a yellow pages service. The
global model of a virtual enterprise focused in its
mission, can be viewed as an Holon. The knowledge
model of the holon follows a Discrete Event
Dynamic Systems Model (DEDS), where each one
of the steps that conforms the mission is described
by means of an operation region. Thus, a conformed
enterprise (virtual or not) is considered as an
enterprise holon which is composed by a set of
Production Units (inside production units or
enterprises) conforming the Production Units
Holonic System. The coordinator of the conformed
enterprise is charged to manage, control, and re-plan
each one of the steps of the mission in order to
402
Chacon E., Besembel I., Rivero D. and Cardillo J. (2007).
HOLONIC PRODUCTION PROCESS: A MODEL OF COMPLEX, PRECISE, AND GLOBAL SYSTEMS.
In Proceedings of the Fourth International Conference on Informatics in Control, Automation and Robotics, pages 402-408
DOI: 10.5220/0001632704020408
Copyright
c
SciTePress
complete it. The established chronogram of the
conformed enterprise generates a particular mission
for each one of the Production Unit Holon (PUH).
Each step of the selected production method by the
PUH is associated to an operation region. The
coordinator of each PUH is charged to manage,
control, and re-plan each one of the steps of the
selected production method. In holonic architecture,
the groups are managed by itself following its
internal resources state knowledge, the production
order advance, and the knowing of its production
method that permits to obtain the product. Thus, a
holon is composed by one or more holons. The
advantage of use a holonic approach is due to have a
reference model that describes the composition of
the conformed enterprise (virtual or not) structure.
Here, a conformed enterprise and a holon are
modeled by following a business model where the
value chain and the product flow both establish the
base of the global modelling of a conformed
enterprise. In this work, we present a reference
model under the holonic approach that permits to
have a description of the production process
(conformed enterprise) as an embedded system
based on its business model, value chain, and
product flow. This presents one enterprise
(conformed enterprise) as a network of enterprises
(production units) composed to follow a production
mission. Section 2 is devoted to show the conformed
enterprise modelling method. Section 3 describes the
holonic approach of the production system, and
section 4 presents the conclusions and future works.
2 MODELING OF A
CONFORMED ENTERPRISE
A conformed enterprise describes both enterprises
composed by several semi-independent units or
virtual enterprises. This is due to the utilization of a
production model in conjunction with a value chain
and a production flow. Both enterprises are
modelled in the same manner. Thus, the value chain
expresses the sequence of the aggregate value of a
product (transformation, storage or transport) by
following of the production process itself. The use of
the value chains is the base to develop models of the
different business process that are specific of an
enterprise. A graphics representation of the value
chains is shown in figure 1. The product flow can be
defined as the different transformation stages, which
follows a resource (or a set of them) until the final
product achieving. The conjunction of the value
chain plus the product flow results the production
flow, which is the aggregate of functionalities and
transformations of the resources to generate the final
product.
...
...
...
...
Process 1 Process i
Process 2
Process N
Process i.1 Process i.j Proceso
i.m
...
...
...
...
Process 1 Process i
Process 2
Process N
Process i.1 Process i.j Proceso
i.m
Figure 1: Value chains.
Each stage of the value chain (Input resources,
processing or transformation and storage) of the
production flow is also viewed as a Production Unit
(PU), where the characterization of each PU depends
on how the resource (or a set of them) evolves, such
as: continuous, batch, manufacture, or hybrid.
Additionally, each PU does a specific transformation
depending on the properties of the resource (or
resources). However, it is possible to found common
or generic elements that characterize a PU in a
production flow. Each element is viewed as a
process inside of the PU. These processes are as
follows:
A process to take hold of resources
A process of transformation/transport
A process of storage between each PU
process
Initially, resources are located and obtained for
the PU. The process to take hold of PU resources
warrants resources for a determined production
recipe. After, the PU selects a production method
required to transform the raw material. The selection
of the production method depends on the resources
properties, and then it is carrying out the
transformation process. When the transformation
process is finished, the transformed resource is
storing and waiting for the need of another PU.
Figure 2 shows a structural model of a PU. This
model not only presents the controlled and
supervised system (control and supervision process
plus the production process) that makes the
transformation, also beholds the product plan,
production methods, configuration, and management
of the resources that are needed in the production
process. This structural description is the base to
extract the main information to do a planning of the
PU by considering which values or variables permit
the description of the PU state, such as: performance
indicators, reliability, and so on. Other variables that
may be taken into account are: quality of the
product, expected quantity of product, production
capacity, storage capacity (minimal and maximal),
etc. For example, PU production capacity is related
to the transformation process capacity, and also to
HOLONIC PRODUCTION PROCESS: A MODEL OF COMPLEX, PRECISE, AND GLOBAL SYSTEMS
403
the storage capacity, if and only if raw material and
the rest of the resources are guaranteed.
An object-oriented structural model of the PU
drawing by means of the Unified modeling
Language (UML) (JçI. Jacobson,
www.rational.com/uml), (A. Muller, 1997) is
presented in figure 3. The class diagram uses
rectangles to represent classes and lines to represent
relationships among classes. This diagram includes
three kinds of relationships, such as:
generalizations/specializations (arrows not fulfilled),
associations (lines), and compositions (line finished
in a filled diamond).
Figure 3 shows different entities or classes in the
PUH and how they are related. In particular, it is
highlighted a special class which is related to an
association between the classes ProductionPlan and
Product, named ProductPlan. Also, the class
Configuration which is charged to register all of the
different configurations of resources, production
process, control and supervision software, and
production method, as an association class between
the four aforementioned entities. It is viewed the
classification of the resources managed by the PU in
order to accomplish its production plan that support
the enterprise plan.
Resources
Tranformation
Transport
Storage
Raw
material
PUH
Finished
product
Resources
Tranformation
Transport
Storage
Raw
material
PUH
Finished
product
Figure 2: Model of a Production Unit.
For lack of space, this class diagram is showed
in a concise form; each class has a set of properties
(attributes and relationships) and operations, which
support the behavioural model of the PU.
The embedded model of figure 4 shows the
decisions scheme needed for each path of the value
chain of a PU. Our proposition uses an embedded
model that is based on the description of a Holon.
This model presents level works composed by
the production process and each one of the
established control loop. The designed controllers
(that takes decisions) are inside the communications
and information architecture, which needs
applications and industrial networks in order to
capture actual variable values, by means of sensors,
and to indicate controller actions, by means of
actuators. Thus, the controlled productive process is
viewed as a system that need to be controlled
(supervise, monitor, manage) by a supervisor. This
permits to view the whole productive system as an
embedded system conformed by a path of the value
chain that takes products, transform-them to
generate another derived product.
Figure 3: UML Class Diagram of a Production Unit.
3 HOLONIC APPROACH IN
PRODUCTION SYSTEMS
A holon for a manufacturing enterprise is defined as
a constructor block; cooperative and autonomous for
transforming, transporting, storing and/or validating
physical objects and information (H. Brusel, 1998).
A holon has the autonomy to create and control the
execution of its owns plans, it may cooperate with
other holons to jointly develop an acceptable plan to
reach the system mission. The cooperation among
holons is accomplished by one evolution of the
holarchy in the organization (a holon system).
In a Holonic system production, the objective is
to achieve a complete spectrum of the range of the
control function that goes from the production plans,
that controller at the highest level, until the
process/machine that control the lowest level.
A Holon possesses two constituent elements: a
connected transformation system and a system of
taking of decisions. The decisions system monitors
the resources and the evolution of the order that are
being controlled in the plant floor, by associate
elements for such an end.
Transducer
Supervisor
u(k)=g(Cond,x(k))
ObserverObserverObserver
TransductorTransductor
Physical
Process
Sensor
Instrumentation
Actuator
Instrumentation
Transducer
Controller
u(t)=g(Xop,x(t))
Obser vadorObs ervadorObser vador
TransducerTransducer
x’(k+1)=f(x(k),u(k))
y(k)=h( x(k))
x’(t)=f(x(t),u (t))
y(t)=h(x(t))
Physical
Image
Products Transformation
Products
Figure 4: Production process embedding model.
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The integral automation of systems outlines a
global vision of the productive process, where each
element that intervenes in the production should be
taken into account to be able to control, to
supervise, and to management the production, to
see figure 5. The automation scheme is based on the
construction of models that represent the Unit of
Production so much in its structural aspect, like in
its dynamics. The control schemes assure that the
behavior of the system is inside that wanted, for that
which the knowledge that one has of the state of the
system allows to evaluate which should be the viable
control actions with the purpose of assuring that the
system reaches the wanted state.
In the productive system, the control is
subordinated to the objective fixed to the Unit of
Production, and the objectives are determined for
what the Unit of Production can make.
The process has a proper behaviour that depends
on the physical and chemical laws in particular in a
condition of given operation. This behaviour it can
describe formally as a Hybrid Dynamic System.
When having the description of the dynamics,
the behaviour can be controlled by a automatic
supervisory system or by means of the intervention
of a human being.
The product of the production process is
obtained by means of a group of resources that can
suffer changes in the time, thus the information of
the state of the process, and of the resources should
be continually monitoring with the purpose of
determine, if the system completed the production
objective, or on the contrary it could not complete
the production objective by failure in some of the
resources. This change should be management to
define a new production scheme in the Unit of
Production or to verify in another level if it is
possible to have a form of assuring the objective
fixed for the set of Units of Production.
Head
Neck
Body
Take of decision
Aplications
Process
Object
Server
Gui server
Net
Figure 5: Integral automation of systems.
Considering the Unit of Production with the
capacity to have autonomy (a Holon: Holon Unit of
Production, HUP). HUP is composing of a BODY,
NECK, and HEAD. In the body is where the
processes: of transformation of the matter, of storage
or transport are developed. This it is carried out by a
group of physical devices as reactors, compressors,
store, etc.. In the head are the mechanisms of taking
of decisions, based on the knowledge of the
production process and the necessary resources.
These mechanisms of taking of decisions are
developed by the classic techniques of supervisory
control or by approach of intelligent systems. The
neck is the interface between both, this is composed
by the whole infrastructure tele-informatics that
stores and transports the information. Thus, in the
head are the applications of taking of decisions that
determine the behaviour that should have the body.
In the neck is the communication mechanism
between the head and the body (process), their
implementation is all the mechanisms that allow to
capture information of the process and to send
commands to the process. See figure 6.
Process
Control
Management Maintenance
Figure 6: Relation ships between Holon and TIC
infrastructure.
3.1 Holonic Control Loop
The basic functional unit for the automation of a
production system is the control loop. This control
loop is redefined how the Holonic Control Loop
(HCL), it possesses all the characteristics of a
Holon.
The HLC is conformed by a body that contains the
physical process that possesses implicit the actuator
and the set of sensors and whose model, without
losing generality, we can describe as a dynamic
system in state equations. The neck of the HCL this
conformed by the architecture tele-informatics and
proper applications that are able to capture, to try, to
store, to adapt, and to transfer so much information
of the sensor as toward the actuator. The head of the
HCL (controller) is conformed by the mechanism of
taking of decisions, this mechanism can have a rigid
form (PID, etc.) or not (neuronal net, etc.). This
controller, that is able to regulate to an operation
HOLONIC PRODUCTION PROCESS: A MODEL OF COMPLEX, PRECISE, AND GLOBAL SYSTEMS
405
point, is designed using the physical model of the
process (knowledge model), its can be described by
dynamic equations and /or algebraic that dependent
of the operation point, of the state or output and of
parameters that belong to an operation region. In
definitive the Holonic Control Loop is an
autonomous system that possesses two input and two
outputs characterized by products and information.
Input Product: products supplies and resource. Input
Information: Controller’s type, Operation Point,
Parameter of Controller. Output Product: sub-
product or finished product. Output Information:
State of the controller process. To see figure 7.
Figure 7: Holonic Control Loop.
3.2 Supervisor Holon
As we know, a process possesses more than a
control loop. To each control loop we have redefined
as the HCL. The management of all the loop control
relapses in a supervisor. The supervisor possesses all
the characteristics of a holon. Thus, when
composing all the loops control we obtain the
Controlled Holonic Systems. See figure 8.
The Controlled Holonic System is a system that
has i models (maybe one for each control loop), each
model has a set the m of nominal values of operation
that can be reached with a set the j types of
controllers which are adjusted under an approach
determined with n parameters. Just as it shows it the
figure 9
Control Loop Holon
x’(t)=f(x(t), g(Xop,x(t),p))
y(t)=h(x(t))
Controller Holonic System
g( ), Xop, p
CLH State
Control Loop Holon
x’(t)=f(x(t), g(Xop,x(t),p))
y(t)=h(x(t))
Controller Holonic System
g( ), Xop, p
CLH State
Figure 8: Controller Holonic System.
Controlled Holonic System
(
)
(
)
()
)t(xh)t(y
p),t(x,Xopg),t(xf)t(x
ii
nimjiii
=
=
nmj
p,Xop(),g
CLH State
Figure 9: Embedding Controlled Holonic System.
In the same manner that the previous sub-section
the Supervisor Holon (SH) is conformed by a body,
a neck and head. The Body of SH is conformed by
the Controlled Holonic System which generates state
values of the process (as sensors), and possesses
implicit actuator given by: g (), Xop, p. The neck of
SH is conformed by the tele-informatics architecture
and set of applications that allow to detect events
(they are able to capture, to try, to store, to adapt,
continuous information of the state variable in
events) as generating the set point (g (), Xop, p)
toward the loops control. The head of the SH this
conformed by the mechanism of taking of decisions,
that is design using approach of modelling of
Discrete Event Systems generated by the Controlled
Holonic System.
In definitive the Supervisor Holon is an
autonomous system that possesses two input and two
outputs characterized by products and information.
Input Product: products supplies and resource. Input
Information: recipe, scheduling of Operation. Output
Product: sub-product or finished product. Output
Information: State of the supervisor process. See
figure 10.
3.3 Holonic Production Unit
It is possible that a production process has more than
a supervisor. To each supervisor we have redefined
it as the Supervisor’s Holon. The management of all
the supervisors relapses in a coordinator; this
coordinator possesses all the characteristics of a
holon: Production Unit Holon. Thus, when we
compose all the supervisors, we obtain the
Supervised Holonic System. (See figure 11).
Supervisor
u(k)=g (Xop,x(k),p)
Detecting Event
ObserverObserver
Set point
Supervisor Holon
x’(k+1)=f(x(k), g(Xop,x(k),p))
y(k)=h(x(k))
Xop
Resouces
Product
Neck
Head
Product
SH State
Body
Controlled Holonic System
(
)
(
)
()
)t(xh)t(y
p),t(x,Xopg),t(xf)t(x
ii
nimjiii
=
=
nmj
p,Xop(),g
CHS State
g( ), Xop, p
Figure 10: Supervisor Holon.
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406
Supervisor Holon
x(k+1)=f(x(k), g(Xop,x(k),p))
y(k)=h(x(k))
Supervised Holonic System
g( ), Xop, p
SH State
Figure 11: Supervised Holonic System.
The Supervised Holonic System is a system that
has i models (maybe but of one for supervisor), each
model has a set m of nominal values of operation
that can be reached with a combined j of types of
recipes which are adjusted under an approach
determined by supervisor with n of parameters. Just
as is shown it the figure 12.
(
)
(
)
()
)k(xh)k(y
p),k(x,Xopg),k(xf)1k(x
ii
nimjiii
=
=+
nmj
p,Xop(),g
SHS State
Supervised Holonic System
Figure 12: Embedding Supervised Holonic System.
In the same manner that the previous sub-section
the Production Unit Holon (PUH) is conformed by a
body, a neck and head. The Body of PUH is
conformed by the Supervised Holonic System which
generates state values of the supervisor process (as
sensors), and possesses implicit actuator given by: g
(), Xop, p., i.e. recipes, scheduling, etc.. The neck of
PUH is conformed by the tele-informatics
architecture and set of applications that allow to
detect events (they are able to capture, to try, to
store, to adapt, information of the state variable of
the supervised process in events) as generating the
set point (g (), Xop, p) toward the supervisor. The
head of the PUH this conformed by the mechanism
of taking of decisions, that is design using approach
of modeling of Discrete Event Systems generated by
the Supervised Holonic System.
In definitive the Production Unit Holon is an
autonomous system that possesses two input and two
output characterized by products and information.
Input Product: products supplies and resource. Input
Information: negotiated production demand. Output
Product: finished product. Output Information: State
of the productive process. See figure 13.
Coordinator
u(k)=g (Xop,x(t),p)
Detecting Event
ObserverObserver
Recipes
Production Unit Holon
x(k+1)=f(x(k), g(Xop,x(k),p))
y(k)=h(x(k))
Xop
Resources
Product
Neck
Head
Product
PUH State
g( ), Xop, p
Body
Supervised Holonic System
)
()
)k(xh)k(y
p),k(x,Xopg),k(xf)1k(x
ii
nimjiii
=
=
+
nmj
p,Xop(),g
SHS State
Figure 13: Production Unit Holonic.
4 CONCLUSION AND FUTURE
WORK
In the work, we show an implemented architecture
that allows to have a recursive (embedded) structure,
represented by each Holon. The information stays
up-to-date by means of mechanisms topologically
equal. The coordination is carried out by means of
supervisors generated for each built configuration
based on a production mission. The stages for the
supervisor's construction are defined like one of
negotiation. This negotiation to define the objective
and the generation of synchronization points based
on the defined configuration. Once finished the
stages of selection of the configuration and
establishment of the synchronization points the
supervisor you instance for the duration of the
mission.
It is necessary to establish negotiation
mechanisms for the establishment of the mission,
since the global knowledge of the production
capacities is known internally, and the configuration
is obtained after the evaluation of the different arisen
alternatives of each participant's internal capacities.
The protocol Contract Net of the FIPA appears as
the most suitable mechanism for the establishment
of a common mission.
ACKNOWLEDGEMENTS
This work is partially supported by the ECOS-
NORD Program France-Venezuela on virtual net of
production
HOLONIC PRODUCTION PROCESS: A MODEL OF COMPLEX, PRECISE, AND GLOBAL SYSTEMS
407
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