J. Software Engineering & Applications, 2010, 3: 109-118
doi:10.4236/jsea.2010.32014 Published Online February 2010 (http://www.SciRP.org/journal/jsea)
Copyright © 2010 SciRes JSEA
The 3+1 SysML View-Model in Model Integrated
Kleanthis Thramboulidis
Visiting Professor Helsinki University of Technology, Electrical & Computer Engineering, University of Patras, Patras, Greece.
Email: thrambo@ece.upatras.gr
Received October 21st, 2009; revised November 6th, 2009; accepted December 1st, 2009.
Software is becoming the driving force in today’s mechatronic systems. It does not only realize a significant part of
their functionality but it is also used to realize their most competitive advantages. However, the traditional development
process is wholly inappropriate for the development of these systems that impose a tighter coupling of software with
electronics and mechanics. In this paper, a synergistic integration of the constituent parts of mechatronic systems, i.e.
mechanical, electronic and software is proposed though the 3+1 SysML view-model. SysML is used to specify the cen-
tral view-model of the mechatronic system while the other three views are for the different disciplines involved. The
widely used in software engineering V-model is extended to address the requirements set by the 3+1 SysML view-model
and the Model Integrated Mechatronics (MIM) paradigm. A SysML profile is described to facilitate the application of
the proposed view-model in the development of mechatronic systems.
Keywords: Systems Engineering, System Modeling, Mechatronic Component, Model Driven Development, Model
Integrated Mechatronics, SysML Profile, V-Model, IEC61499
1. Introduction
Software does not only implement a significant part of
the functionality of today’s mechatronic syste ms, but it is
also used to realize their most competitive advantages. It
is the evolving driver for innovations in many mecha-
tronic systems and in general it is considered as th e driv-
ing force in improving this kind of systems. However,
the traditional development process is wholly inappro-
priate for the development of systems characterized by
complexity, dynamics and uncertainty as is the case with
today’s mechatronic systems [1]. According to the tradi-
tional development process the constituent parts of the
mechatronic system, i.e. the mechanical, electronic and
software, that constitute the system are developed inde-
pendently and then are integrated to compose the final
system. The software development starts when the de-
velopment of electronic and mechanical is already at a
stage where any change in these parts is expensive and
time consuming. This is why the mechanical and elec-
tronic properties impose several constrains and narrow
the solution space for software development. Moreover,
as claimed in [2] “the actual cooperation during the con-
struction is less developed. There is no joint development
process, no joint tool usage, no joint modeling formalism
and no joint analysis. Every discipline has its own ap-
proach es”. As a r esult of this, th e curren t process that is
traditionally divided into software, electronics and me-
chanics, emphasizes on domain-spanning design meth-
ods and tools and is unable to address the demand for
synergetic mechatronic dependability predictions; this
is why many products suffer from severe dependability
problems [3].
An integrated framework for the construction of
mechatronic systems is missing [2]. Such a framework
should address current challenges in the development of
mechatronic systems that include among others, syner-
gistic modeling and integration, design synchronization,
as well as model execution and analysis. It should pro-
vide the infrastructure required for applying a tight inte-
gration of mechanics with electronics and software in
order to replace conventionally designed mechanical and
electromechanical systems into smart ones where sig-
nificant part of functionality will be implemented by
software. It is also expected to result in massive im-
provements in system’s Quality of Service (QoS) char-
acteristics and allow a smooth integration of dependabil-
ity predictions during the early development phases.
Model Integrated Mechatronics (MIM) [4] is a para-
digm that was proposed to address the need for an inte-
grated development in mechatronic systems. MIM sup-
ports the model-driven development of complex mecha-
The 3+1 SysML View-Model in Model Integrated Mechatronics
tronic systems (MTSs) through the evolution of models
that have as primary construct the mechatronic compo-
nent (MTC). The concept of component has already been
adopted in the development process of manufacturing
systems by other researchers too. However, they mostly
focus on the software part of the component; they do not
address the whole development process; and they do not
provide an architecture for the concurrent engineering of
all constituent components, i.e., mechanical, electronic
and software.
In this paper, the Systems Modeling Language (SysML)
[5] is adopted for the system’s modeling process in the
MIM paradigm. An architectural view-model, the one
called 3+1 SysML is proposed to address the synergistic
integration of the constituent parts of mechatronic sys-
tems. The main view is the SysML view that corresp onds
to the mechatronic layer of the MIM Architecture. This
view captures the system model that is the one con-
structed by the MTS developer. Each of the three views
is used to describe the system fro m the perspective of the
corresponding discipline. Specific tools of every disci-
pline may be exploited for the model execution and
analysis of the SysML models.
SysML is used to represent the models of the mecha-
tronic system that are proposed by the MIM paradigm. A
SysML profile was defined using Papyrus, an open
source tool for graphical UML 2/SysML modeling. This
profile supports not only the modeling of mechatronic
systems using the concept of mechatronic component but
also a hybrid development process that integrates the
traditional approach with the MTC-based one, to allow
the reuse of legacy systems. It provides a SysML based
implementation of the MIM architecture that will allow
the MIM paradigm to be exploited in the development
process of real world mechatronic systems. An effective
development process that exploits the 3+1 SysML
view-model and the SysML profile is described extend-
ing the well-known in software engineering V-model [6].
The remainder of this paper is organized as follows. In
the next section, a brief introduction to the MIM archi-
tecture and the SysML is given and the related work is
briefly discussed. Section 3 presents the proposed 3+1
SysML view-model that emphasizes the importance of
the common system-level model. In Section 4, a SysML
profile that represents the artifacts used in the MIM ar-
chitecture is described. Section 5 presents the proposed
modifications to the widely used in software systems
V-model to address the needs of the MTS development
process. Future developments and research challenges
are discussed in Section 6 and the paper is concluded in
the last section.
2. Background and Related Work
2.1 A Brief Introduction to MIM
The upper layer of the MIM architecture that is shown in
Figure 1, i.e. the mechatronic layer, was defined to sys-
tematically address complexities in the model-driven
development process of component-based mechatronic
systems. This layer is projected into three dimensions
representing the application, the resource, and the me-
chanical process respectively. The controlling application
software is modeled in the application layer, while the
hardware, i.e., computing and communication, as well as
the software resources that constitute the infrastructure
required for the execution of the controlling application
software, are modeled in the resource layer. Mechanical,
hydraulic and pneumatic parts are modeled in the me-
chanical layer.
Mechatronic system integrators work horizontally in
the model evolution dimension of the MIM architecture.
They interactively compose the MTS using already de-
fined MTCs without worrying on lower layers’ imple-
mentation details. They go through a model-driven de-
velopment process to build the MTS using descriptions
of already existing MTCs. They only have to capture the
application logic in application layer components, as well
as to identify their required QoS characteristics from the
resource layer infrastructure.
MTC builders work in the model integration dimen-
sion and apply an information integration process that
crosses the boundaries between mechanical, electronic,
and computer science fields. They work horizontally and
vertically, either top-down or bottom-up, in the lower
three layers of the architecture in a concurrent way. Con-
structed MTCs are stored in MTC repositories to be dis-
covered and used by mechatronic system integrators [7].
MIM is a new paradigm that promotes model integra-
tion not only of implementation space artifacts but also
of early analysis and design phase ones. It promotes
Figure 1. The Model Integrated Mechatronics (MIM) ar-
chitecture [4]
Copyright © 2010 SciRes JSEA
The 3+1 SysML View-Model in Model Integrated Mechatronics
Copyright © 2010 SciRes JSEA
Figure 2. SysML diagrams and its comparison with UML 2 [5]
The other new diagram, i.e. the parametric diagram, is
used to describe the constraints among the properties
associated with blocks. It allows the specification of co n-
tinuous components by parametric constraints on class
attribute values expressing corresponding differential
equations. However, the syntax and the semantics of be-
havioral descriptions captured in parametric diagrams
have not been defined to allow the integration with other
simulation and analysis modeling techniques for the
proper execution of the models. So, the parametric dia-
gram is used to integrate the system descriptive behavior
and structure models expressed in SysML with other
simulation and engineering analysis models such as per-
formance, reliability, and mass property models.
reuse at the mechatronic level and significantly decreases
development and validation time of the system. MIM
addresses the need for synergistic integration at the
model and process levels; it facilitates the integration
between the design processes of the different disciplines
which is the approach considered as the most effective to
improve the development process of mechatronic sys-
tems. The other two approaches being: implementation
time integration and design time integration at data and
model level [8].
2.2 Systems Modeling Language (SysML)
SysML was developed to support the specification,
analysis, design, verification and validation of a broad
range of complex systems [5]. These systems may in-
clude hardware, software, information, processes, per-
sonnel, and facilities. The objective o f SysML is to unify
the diverse modeling languages currently used by system
engineers. SysML reuses a subset of UML 2 [9] and pro-
vides additional extensions needed to address system
engineering aspects not covered by UML 2. It includes
diagrams that can be used to specify system requirements,
behavior, structure and parametric relationships. Re-
quirements diagram and parametric diagrams are the new
diagram types proposed by SysML, as shown in Figure 2
which presents the diagrams that are used by SysML.
The fact that SysML is based on UML 2, will allow
system engineers modeling with SysML and software
engineers modeling with UML 2 to collaborate on mod-
els of the mechatronic system. This will improve com-
munication among the various stakeholders who partici-
pate in the mechatronic systems development process
and will promote interoperability among modeling tools
in different disciplines. All the above mentioned charac-
teristics make SysML ideal for the representation of
models used in the MIM paradigm.
2.3 Related Work
SysML provides modeling constructs to represent
text-based requirements and relate them to other model-
ing elements. The requirement diagram can be used to
represent many of the relationships that exist between
requirements and visualize them. It provides a bridge
between traditional requirements management tools and
the other SysML models. It can be used to depict the
requirements in graphical, tabular, or tree structure for-
mat and highlight their relationships, as well as to cap-
ture the relationships between requirements and other
model elements that satisfy or verify them.
Several researchers are already working in the direction
of improving the effectiveness of the development proc-
ess of mechatronic systems. Schafer and Wehrheim [2]
survey on current developments in mechatronics and
present the architecture of their mechatronic rail system
that seems to provide an excellent platform for studding
and analyzing future developments and research chal-
lenges in mechatronic systems. They identify the need
of an integrated framework for the construction of
mechatronic systems and they discuss future trends in
mechatronics especially from the software engineering
The 3+1 SysML View-Model in Model Integrated Mechatronics
point of view. Habib [10] argues on the urgen t need for
theories, models, and tools that should facilitate model-
ing, analysis, synthesis, simulation, and prototyping of
mechatronic systems. He emphasizes the argument that
the approach based on optimization within each do main
separately will not result in the optimum system design,
and he proposes a data and model integration approach
to address the integration problem. Burmester et al. [11]
claim that in today’s mechatronic systems most of the
control and reconfiguration functionality is realized in
software. They present mechatronic UML to exploit the
Model Driven Architecture approach for the design of
hybrid mechatronic real-time systems that have to fulfill
safety-critical requirements. “Mechatronic UML” is
defined as an extension of UML to built platform inde-
pendent models for mechatronic systems. Various UML
mode ls h ave b e en ex t ended to cover the req u ir e men ts o f
modeling the structural view as well as the behavioral
view of the system. However, the proposed extension is
used to mod el only the sof tware part of the mech atronic
system. Authors in [12] briefly refer to a process model
of Robert Bosch GmbH for the development of mecha-
tronic systems in Motor Vehicles to support aspects
such as reuse, exchangeability, scalability and distrib-
uted development. They use the concept of mechatronic
component, even though not well defined, as the basic
construct of their process. They argue: a) on the need of
a clear specification of component interfaces; and b) the
great contribution of re-use to increase the quality prop-
erties of mechatronic systems and decrease develop-
ment time. Nordmann [13] is using the concept of
mechatronic component and presents an example of
using Active Magnetic Bearings to increase perform-
ance, reliability, reusability and longer lifetime. Authors
in [14] propose for the development of multidiscipli-
nary systems, such as mechatronics, the integration of
the various domain-specific tools. They mainly focus on
the integration of used data and models and not on a
process level integration. Moreover, none of these ap-
proaches provide a high level architecture for an inte-
grated, synergistic development process for mecha-
tronic systems and they do not describe a systems level
development process based on the mechatronic compo-
nent and the emerging standard in the domain that is
3. The 3+1 Architectural View Model
Each of the three lower layers of the MIM architecture
provides a specific view of the central models that are
captured in the upper layer, i.e. the mechatronic layer.
Each view is used to describe the system from the per-
spective of the corresponding discipline. The software
view (s-view), for example, provides the models of the
software part of the MTS and allows for software spe-
cific tools to be used to elaborate and further refine these
models. The IEC61499 function block model is an ex-
ample of such a domain specific model that can be used
to further refine the s-view [15]. Figure 3 depicts the 3+1
SysML view-model that is proposed for the development
of mechatronic systems. The MTS model is the heart of
this architecture and is depicted in the center of the pic-
ture. It is surrounded by 4 views which correspond to the
roles that engineers play during the development process
of mechatronic systems.
The main view is the MTS-view that corresponds to
the mechatronic layer of the MIM Architecture. This is
the view that is used by the MTS developer. The other 3
views correspond to the 3 lower layers of the MIM ar-
chitecture. The m-View, for example, corresponds to
the Mechanical layer of the MIM architecture and cap-
tures all the mechanics, hydraulics and pneumatics of
the MTS model. These models are generated by pro-
jecting the MTS models to the mechatronic layer and
are fully synchronized with the MTS models. Any
modifications imposed by the mechanical engineer to
the models of this view directly affect the correspond-
ing central MTS models. Moreover, modifications done
by the MTS developer on the central models directly
affect the corresponding m-view models. The m-view is
mainly used during the primitive MTC development
process where a concurrent, synergistic engineering on
the three views is adopted at the primitive MTC level as
a more eff ective pro cess. It is a lso used to have a whole
view of the mechanical system model and perform op-
timization and analysis activities on this.
Figure 4 presents the structure of the primitive MTC
and its interfaces to the environment. A primitive MTC
may expose to the environment mechanical, electronic
and software interfaces through the corresponding ports.
Interfaces between its constituent parts are also shown.
Sensors and actuators are used to realize the interactions
Figure 3. The 3+1 SysML view-model for mechatronic sys-
tems development
Copyright © 2010 SciRes JSEA
The 3+1 SysML View-Model in Model Integrated Mechatronics113
Figure 4. The structure of the primitive mechatronic com-
between the mechanical part and the electronic one.
This means that sensors and actuators are fully encap-
sulated by the MTC construct. The mechanical part in-
teracts with the environment only through mechanical
ports that are mainly in the form of mounting ports or
ports for flow of material or energy. A detailed descrip-
tion of mechanical connections that can be discrimi-
nated into fixed and moveable arrangements is given in
[16]. The sOperatorPanel, i.e. the software part of the
OperatorPanel primitive MTC, exposes its functionality
along with the corresponding QoS through a provided
interface of the sPort. A hosting functionality for appli-
cation specific components will be optionally provided
by the ePort.
Currently there is no tool to execute the MTS models,
not even to analyze their behavior. Discipline specific
tools may be exploited for the execution and analysis of
MTS models. This is obtained by the proper integration
and coordination of specific model execution and analy-
sis tools of the three views. The tool of each view is used
to execute the primitive MTC model of its perspective so
it has to provide specific interfaces to the tools of the
other views, in order to implement the interactions of its
own part to the other parts of the primitive MTC. The
arrows that cross the boundaries between the three views
in Figure 3 represent the interactions of the correspond-
ing models and have to be implemented by specific in-
terfaces of the model refinement, analysis and execution
tools of the three disciplines. The AP233 or more for-
mally the ISO 10303-233 standard for systems engineer-
ing [17], that provides a data exchange format for the
reliable interchange of data between software tools may
be exploited to effectively implement these interactions.
The execution and analysis of the primitive MTC is ob-
tained through a collab oration of the correspond ing tools
of the three views. It is clear that the contribution of the
three views’ specific tools is restricted at the primitive
MTC internal level while the execution and analysis of
MTC models is done at the MTS level with the coordina-
tion and synchronization between MTCs carried by this
level. This makes the tool integration a major challenge
in the domain of mechatronic systems.
The 3+1 SysML view-model when used with the MTS
V-Model that is described in one of the following sec-
tions, promote the synergistic integration of the three
constituent parts of the mechatronic system and empha-
sizes the importance of a common model for the system.
However, this model can also be used with the trad itional
development process that is based on the independent
development of constituent parts of the mechatronic sys-
tem and their subsequent integration. Even in this case
the existence of a common model for the system greatly
improves the effectiveness of the development process.
It should be noted that in each view the corresponding
discipline’s specific architectures and tools may be ex-
ploited, as for example the 4+1 architectural view [18]
that may be exploited in the context of the e-view by the
software engineer or the MTC developer/integrator.
4. Using SysML to Model the MIM Artifacts
The Systems Modeling Language can be used to repre-
sent the artifacts of the mechatronic systems develop-
ment process that correspond to the system level activi-
ties. These include requirements specifications for the
MTS and MTC levels, as well as architectural specifica-
tions for the MTS and MTC levels. UML 2.0 will be
used for the modeling of the software part of the primi-
tive MTC and corresponding tools from the electronics
and mechanics domain will be used for the modeling of
the other two constituent parts of the MTC. In this sec-
tion the modeling of the MTS and MTC levels using
SysML is considered. It is evident that specific interfaces
have to be defined for the integration of the different
views and these interfaces have to be realized by the
tools used in the various disciplines to create a com-
pletely integrated tool chain to support the MTS devel-
opment process. The SysML to AP233 mapping [19] is
towards this direction.
4.1 Modeling of the Mechatronic Component
The MTS stereotype that is shown in Figure 5, which
presents part of the SysML4MIM profile, is considered
as a composition of MTSComponents and MTSConnec-
tors (not shown in the figure). The abstract stereotype
MTSComponet was defined to provide more flexibility
in system modeling. It allows the definition of the dif-
ferent disciplines’ components in any level of the sys-
tem’s decomposition hierarchy; it also allows the appli-
cation of the traditional approach where the system is
considered as consisting of mechanical, electronic and
software components. An MTSComponent that is ab-
stract is specialized to the MTC abstract stereotype and
the mCompoment, eComponent and sComponent stereo-
ypes. The mComponent stereotype is used to represent t
Copyright © 2010 SciRes JSEA
The 3+1 SysML View-Model in Model Integrated Mechatronics
Copyright © 2010 SciRes JSEA
Figure 5. SysML4MIM profile (part); the MTS stereotype
in the model any mechanical component of the mecha-
tronic system. This way of modeling allows the profile to
be used also in the traditional development process of
mechatronic systems since the MTS may be considered
as a composition of m, e and sComponents. The MTC
stereotype which is also abstract is specialized to the
CompositeMTC and the PrimitiveMTC. This allows a
hierarchical decomposition scheme for the MTS up to the
level of primitive MTC th at is considered as composition
of m, e and sComponents. An m, e and sComponent may
be further decomposed in corresponding Components
allowing a component based synthesis in each one of the
three disciplines. The SysML4UML profile that was cre-
ated using Papyrus, an open source tool for graphical
UML 2 modeling (http://www.papyrusum-l.org/), im-
ports the UML4SysML profile that is already supported
by Papyrus. This allows the MTS stereotype to extend
the Block stereo type of the UML4 SysML profile. All the
other components also extend the Block stereotype even
not shown in figure. The proposed SysML4MIM profile
allows the synergistic integration in the development of
mechatronic systems to any level of granularity down to
the primitive MTC component which is the one that is
not decided or it is not possible to be decomposed into
lower layer MTC components.
4.2 Modeling of the Mechatronic Port
Allowable inputs and outputs of an MTC are defined
using the concept of the port. This allows the design of
modular reusable MTCs, with clearly defined interaction
points and interfaces with the environment. The construct
of Mechatronic port (MTPort) was defined as an exten-
sion of the UML port to fulfill this requirement. SysML
provides standard ports which support client-server
communication and FlowPorts that define flows in and/or
out of a block. An MTC may own MTPo rts, as shown in
Figure 6, which allows the MTC to declare the items it
may exchange with its environment and the interaction
points through which this exchange is made. Furthermore,
MTPorts allow the MTC to declare the provided to the
environment services but also the services that the MTC
expects from it. An MTPort is defined as an aggregation
of mPort, ePort and sPort. Each port is used to represent
the interaction point of the corresponding part of the
primitive MTC with the environment (see Figure 4). All
these ports extend the SysML port; mPort and ePort ex-
tend it through the SysML flow port while sPort extends
it directly. So, a sPort is characterized by provided and
required interfaces. The specification of what can flow in
or out of an mPort or ePort is achieved by typing them
with a specification of the things that flow in and/or out.
It should be noted that an mPort may accept or transmit
energy or material but may also accept or transmit in-
formation that has been decided to be transferred by me-
chanical means. Of course the same information may be
transferred by electronic signals using an ePort or by
software messages using a sPort. The support of several
alternatives through configuration, results in increased
reuse potential for the MTC. The specification of the
ervices of the sPort is achieved by typing it with the s
The 3+1 SysML View-Model in Model Integrated Mechatronics115
Figure 6. The MTPort stereotype in the SysML4MIM profile
provided and/or required interfaces. Flows of mPorts and
ePorts may be atomic or non atomic; an atomic flow is
specified with a single type representing the items that
flow in or out. A non atomic flow is specified with a flow
specification which lists th e items that constitu te the flow.
A sPort accepts software signals, i.e. packages of infor-
mation, which usually need a more complicated specifi-
cation supported by UML 2.
5. The MTS Development Process
The MIM development process adopts the V-model as
basis and updates it to address the needs of the mecha-
tronic systems domain. Figure 7 presents the proposed
MTS V-Model. A system modeling process is applied
down to the primitive MTC level, as shown in the
left-hand part of the V-model. For primitive MTCs that
have to be constructed, a concurrent engineering process
of all three constituent parts, i.e., mechanics, electronics
and software is adopted, as depicted in the bottom of the
V-Model. The system integration and verification process
is depicted by the right-hand side of the V-model.
MTS-level requirements are captured using the SysML
requirements diagram. Essential use cases, which are
used to capture the functional requirements at this level,
are defined in abstract, simplified, and independent of
technology or implementation way. They are written as
“an abstract dialog representing user intentions and sys-
tem responsibilities, and they are typically small and fo-
cused on a highly specific user goal, yielding a fine-
grained model of user activity” [20]. After the definition
of the essential use cases there are two alternatives to
proceed in the system’s architecture definition phase:
1) Use cases are decomposed in sub-use cases.
2) Responsibilities of the system are identified.
In the first case the decomposition of use cases to
sub-use cases allows: a) the reuse of existing components
on the basis of their requirement specifications that
should have been defined in terms of use cases, and b)
modularity and reuse in requirements specification arti-
facts. In the second case, activity diagrams are defined
for each use case in order to identify the activi-
ties/responsibilities of the actors and the ones that are
required by the system in the context of the specific use
case. After this step the list of abstract activities (func-
tions) that have to be performed by the system is avail-
able. In other words the responsibilities of the system in
Copyright © 2010 SciRes JSEA
The 3+1 SysML View-Model in Model Integrated Mechatronics
Figure 7. The mechatronic system V-Model (MTS V-Model)
the context of the specific use case are defined. The term
responsibility is used to emphasize the fact that only the
abstract definition of the activity/function is provided at
this time and not its implementation.
As a next step, for both alternatives, a system compo-
sition should be proposed to satisfy either the system
use-cases or the system responsibilities. Some use cases
or system responsibilities may be directly supported by
existing mechatronic components. However, it is com-
mon that for a required system level use case or respon-
sibility, a collaboration of MTCs has to be defined in
order to achieve it. The system level use cases and
sub-use cases or the system responsibilities/functions
correspondingly are mapped to system’s components. An
analogous mapping applies also for the non-functional
The definition of system’s structure in terms of MTCs
is a design process and results in the selection of system
components and the definition of their collaboration.
Furthermore each MTC has assigned responsibilities that
are handled in the subsequent phases as its required re-
sponsibilities. The result in both cases is a system archi-
tecture that is comprised of:
a) Class or component diagrams to specify the struc-
ture of the system;
b) Sequence or activity diagrams (or even state charts)
to specify the components’ collaborations to provide the
higher layer functionality.
Domain analysis is used to capture the domain key
concepts and provide the information required to create
the first architectural model of the system. SysML dia-
grams are used to specify the proposed architecture.
Block definition diagrams (bdd) are used to capture the
structure of the system and internal block diagrams (ibd)
are used to capture the components’ interactions, all ex-
pressed using the SysML4MIM profile.
During the architecture definition the developer has to
assign the system required responsibilities to the sys-
tem’s components. This assignment results to an archi-
tectural diagram that represents the system components,
their responsibilities and the components interactions.
The allocation relationship of SysML provides an effec-
tive means to capture this assignment and allow the
navigation between the system models by establishing
cross-cutting relationships among them. There are two
alternatives to proceed in the definition of the architec-
1) The bottom-up approach (synthesis).
2) The top-down (decomposition).
According to the bottom-up approach, for every sys-
tem-level responsibility a set o f commercial off-the-shelf
(COTS) MTCs is selected. We assume that each COTS
MTC has its own provided functions that are well de-
fined by the developer of the MTC [7]. These provided
functions are part of the MTC package that specifies the
real world MTC. QoS characteristics are also included in
the MTC package and can be used to examine if the QoS
aspects of the proposed collaboration scheme satisfy the
required system-level QoS aspects for the specific re-
sponsibility. If the QoS characteristics of this specific
collaboration meet the QoS requirements of the sys-
tem-level required responsibility, the design is accepted.
Either wise corrective actions should be proposed and
analyzed. Corrective actions may include: a) re-engineering
of the collaboration scenario, b) the use of components
with better QoS characteristics than the ones used in the
previous design, or c) a combination of the above. It is
assumed that the MTC developer has already performed
a QoS analysis for the MTC. All this information com-
prises the offered QoS characteristics of the MTC [4]. It
should also be stated that the MTC developer does not
know during the MTC’s development time all the sys-
tems that this MTC will be used in the future.
According to the top-down approach, for every sys-
tem-level responsibility that has not been assigned to a
single MTC, a set of abstract MTCs is defined and the
required MTC responsibilities are specified along with
the required collaboration sche me. Required system-level
QoS characteristics are decomposed to derive the com-
ponent-level required QoS characteristics. This process
results to the definition of the required QoS characteris-
tics at the level of constituent MTCs. The process of de-
riving MTC-level QoS characteristics from system-level
ones is a complex process and has to be defined. At this
time the engineer has well defined required specifications
(functional and non functional, including QoS character-
istics) for every abstract MTC. Using these required QoS
characteristics the engineer is able to select from the
market or his components repository the ones that their
offered QoS characteristics meet the required ones [8]. If
such MTC’s do not exist they h ave to be further an alyzed
in order to be developed.
Advantages and disadvantages for the above ap-
proaches that result in th e definitio n of the arch itecture of
the MTS of its composite MTCs may be identified but it
is expected that in the real MTS development process a
Copyright © 2010 SciRes JSEA
The 3+1 SysML View-Model in Model Integrated Mechatronics117
combination of both approaches will be used resu lting to
a hybrid more efficient approach.
The above process, bottom-up or top-down, is again
applied to every composite MTC that has to be devel-
oped. It is applied iteratively down to th e primitive-MTC
level; the identification of primitive MTCs signals the
end of this iteration. For each composite MTC the system
modeling process as defined by the left-hand side part of
the V-Model is followed. Analysis is applied and its ar-
chitecture is defined in terms of constituent components
(composite and/or primitive). Sequence diagrams are
defined to realize use cases of the MTC and identify the
activities that are involved in the specific use case. This
is not the case for primitive MTCs that have to bypass
the system process and follow a synergistic integration of
the three constituent parts, i.e. mechanic, electronic and
software (MTC synthesis) as shown in the bottom of the
V-model in Figure 7.
For each primitive MTC, verification follows its inte-
gration as shown in the right-hand side of the MTS
V-Model. Each composite MTC is integrated according
to its MTC architecture and then it is verified against its
requirements. After the integration and verification of the
MTCs of the system, the MTS integration test is per-
formed and the MTS is verified against its requirements.
It should be noted that the system analysis phase is
followed by a system architecture design phase as shown
in the proposed MTS V-model. This is also the case for
the V-Model in software engineering. After this point th e
proposed V-model is completely differentiated from the
traditional software engineering V-model. After the sys-
tem architectural design, repetitions of analysis followed
by architecture design for every composite MTC are ap-
plied following the system modeling process up to the
primitive MTC level. This is the point where the system
development process is terminated and the synergistic
integration of constituent parts of the primitive MTC is
performed working independently but in a synergistic
way in the three disciplines. For every primitive MTCs
that has complex software constituent part, a software
V-model can be applied for its development, as shown in
the bottom of the MTS V-Model.
Figure 8 presents two real world MTCs and the Paral-
lel Kinematic Machine evolium MTS, that were devel-
oped based on the basic principles of the MIM architec-
ture by a high-tech Italian company. Each axis of the
Parallel Kinematic Machine has its own intelligence, so
there is no need of an external entity to control the mo-
tion trajectory.
6. Future Developments and Research
Mechatronic systems development is a very complicated
process imposing many challenges. In this section we
refer to the ones that are of higher priority considering
the 3+1 SysML view-model. The identification of the
Figure 8. Real-world MTS and MTCs
mechanical discipline information that has to be captured
in the system level models is one of the challenges. There
are two possible approaches: a) exploit SysML constructs
to represent as much of the mechanical discipline infor-
mation, including component interfaces and behavior;
and b) extend SysML constructs with new ones with the
objective of creating a complete SysML model of the
mechanical component. In the first case specific tools
will be used for further refinement of the mechanical
models and their subsequent execution and analysis. In
the latter, the SysML models have to be automatically
transformed to models of the specific tools for execution
and model analysis. The integration of SysML with the
Modelica language (www.modelica.org/) is towards this
direction. This challeng e is greatly related to the one that
concerns the model execution, analysis and assessment
of models on the MTS-view level.
Fully automated generation of the three views from the
MTS view, as well as automatic update of the MTS-view
with changes in the discipline views are important chal-
lenges that have to be addressed to improve the effec-
tiveness of the process. This also imposes the challenge
of integration of existing mechanical and electronic do-
main design tools.
The identification and definition of reusable MTCs is
another major challenge in mechatronic systems. The
Workpartner [21], a mobile service robot, is planned to
be used in the context of a TEKES (Finnish Funding
Agency for Technology and Innovation) funded project
as a case study for the application of MIM, but also as a
case study for the iden tification of reusable MTCs.
Since many of the MTSs are from the safety critical
domain, the integration of the MTS V-model development
process and the 3+1 SysML view-model with safety engi-
neering is another major challenge for the MIM paradigm
to be effectively exploited in safety- critical mechatronic
7. Concluding Remarks
The traditional approach in the development of mecha-
tronic systems is unable to address the needs of today’s
Copyright © 2010 SciRes JSEA
The 3+1 SysML View-Model in Model Integrated Mechatronics
Copyright © 2010 SciRes JSEA
complex mechatronic systems. An integrated framework
for the construction of mechatronic systems is missing.
The work presented in this paper attempts to contribute
to this direction by: a) using SysML to define the arti-
facts of the MIM paradigm; b) propo sing the 3+1 SysML
view-model imposed by the MIM architecture; and c)
extending the well accepted and widely used in the soft-
ware domain V-model to address the demands of the
mechatronic system development process. However, the
challenges for a fully automated MTS development
process crosses the boundaries of the three disciplines of
mechatronic systems and impose a joint effort and col-
laboration between computer science, electronics and
mechanics. The current status of discipline isolation im-
posed in many cases by the existing structure of engi-
nee ring d egre e progr ams ma kes t he tas k even mo re co m-
8. Acknowledgments
Part of this work has been funded by TIKOSU, a project
belonging to the Digital Product Process -program of the
Finnish Funding Agency for Technology and Innovation
(TEKES). The author wishes to thank the partners and
especially Jarmo Alanen, Kari Koskinen, and Seppo
Sierla for fruitful comments on these ideas. Thanks are
also due to Piero Larizza, Eric Coatanea and Jussi
Suomela for discussions on these concepts.
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