6 th IFAC Symposium on Advances in Control Education, Oulu, Finland, June 16-18, 2003.
COURSE ON DYNAMICS OF MULTIDISCIPLINARY CONTROLLED SYSTEMS
IN A VIRTUAL LAB
Heřman Mann, Michal Ševčenko
Computing and Information Centre
Czech Technical University in Prague
Zikova 4, CZ-166 35 Prague 6, Czech Republic
{mann,sevcenko}@vc.cvut.cz
Abstract: The DynLAB project currently developed by an experienced
international consortium aims at motivating young people to
engineering study, and at improving engineering training using
innovative didactic and technological approaches. The resulting webbased training modules are supported across the Internet by tools like
a robust simulation engine DYNAST, publishing and monitoring
system, and environment for virtual experiments. DYNAST can be
used across the Internet as a modelling toolbox for the MATLAB
control design toolset installed on client computers.
Copyright  2003 IFAC
Keywords: engineering, education, control, design, Internet
1.
presenting ‘textbook’ problems engineered to fit the
‘underlying’ theory without undertaking realistic
modelling of control systems. Professors tend to
teach more and more sophisticated control
algorithms as applied to oversimplified models of
controlled plants. On the other hand, the industry
mostly resorts to rather simple control, but uses very
realistic models to verify the design sufficiently.
INTRODUCTION
The subject of dynamic and control underlies all
aspects of modern technology and plays the
determining role in the World-market competition of
engineering products. Its importance increases with
the ever-growing demands on operational speed,
efficiency, safety, reliability, or environmental
protection. National authorities and entrepreneurs in
many countries, however, report lack of
professionals well qualified in this field as well as a
critical overall decline of interest in engineering
study among young people.
To reverse this gap widening between academia and
industry, it is necessary to attach greater importance
to all phases of the control-design process – namely
to modelling and identification – key factors for
achieving a good design. Nevertheless, only few
engineering schools have introduced realistic
modelling as a distinct topic and have given their
students the opportunity to deal with real-life
problems and practical tasks.
Professional associations call for radical changes in
the engineering curriculum and for innovative
approaches to vocational training (e.g., [1]). The
existing courses are criticised namely for discouraging young people from engineering study by
overemphasis on theory and mathematics at the
expense of practical engineering issues. Dynamics
is covered in several courses separated along the
borders between the traditional engineering disciplines despite the fact that most of the contemporary
engineering products are of multidisciplinary nature.
Computers are often used to carry out old exercises
without radical modification of the curriculum to
exploit capabilities of current software.
Professors often assume that modelling and simulation is just a matter of routine utilising a readymade software package. As they consider such
activity uninteresting academically, many of them
still have had no ‘hands-on’ personal experience in
modelling that they could share with their students.
On the other hand, many engineers working in the
industry are very competent in this field, but they
very rarely publish. Newcomers in large organisations can fill the gaps in their education and training
Automatic control education is criticised for a very
narrow approach [2]. Courses on control are

This is an outcome of the DynLAB Pilot Project partly supported by the Leonardo da Vinci grant No. CZ/02/B/F/PP/134001.
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by learning from old-timers, but those starting in
small enterprises must struggle on their own.
The main target groups of the DynLAB course are
2 PROJECT DynLAB
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distance-education students at different levels
of vocational study and training
practising engineers in the context of their
continuing education or lifelong learning
disadvantaged people who want to study from
their home
teachers intending to innovate the courses on
dynamics and control they teach
industrial enterprises interested in enhancing
the qualification and efficiency of their staff
providers of continuing and life-long-learning
engineering courses
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The above mentioned analysis gave rise to the Pilot
Project Project DynLAB within the Leonardo da
Vinci Vocational and Training Programme. The aim
is to develop and disseminate a Web-based course
on dynamics and control of multidisciplinary engineering systems. The project consortium consists of
the following academic and industrial institutions:
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regular students wishing to complement the
traditional face-to-face courses
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2.1 Project consortium and background
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Computing and Information Centre, Czech
Technical University in Prague (Co-ordinator)
Automatisierung und Prozessinformatik, RuhrUniversität, Bochum
Institute of Technology Tallaght, Dublin
Fraunhofer Institut Integrierte Schaltungen,
Dresden
ABB Automation Control, Västerås
University of Sussex, Brighton
2. PROJECT OUTLINE
2.1 Innovations in the project
The emphasis and style of the proposed course
differs from most of the existing courses by
The project builds on the partners’ experience
gained in the previous projects, namely RichODL
and DynaMit. Outcomes of these two projects
initiated establishing two Virtual Action Groups –
one of them is focused on Multidisciplinary System
Simulation, the other one on Teachware. The Groups
are parts of the IEEE Control Systems Society
Technical Committee on CACSD [3].
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exposing learners to a novel systematic and
efficient methodology for realistic modelling of
multidisciplinary system dynamics applicable to
electrical, magnetic, thermal, fluid, acoustic and
mechanical dynamic effects in a unified way
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introducing learners to the methodology through
simple, yet practical, examples to stimulate their
interest in engineering before exposing them to
rigor math
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giving learners a better ‘feel’ for the topic by
problem graphical visualisation and interactive
virtual experiments
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allowing different target groups to select individual paths through the course tailor-made to
their actual needs and respecting their
background
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allowing both for self-study and remote tutoring
combined with investigative and collaborative
modes of learning
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integrating computers into the course curriculum consistently and giving learners a hands-on
opportunity to acquire the necessary skills

exploiting the computers not only for equation
solving, but also for their formulation minimising thus learners’ distraction of from study
objectives
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giving learners the opportunity to benefit from
‘organisational learning’, i.e. from utilising
knowledge recorded during previous problem
solving both in academia and industry
1.2 Project application areas and target groups
The application areas of the course include dynamics
of:
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electrical, electronic and magnetic circuits
mechanical and automotive systems
electromechanical devices
fluid power and acoustic systems
heat-transfer systems
energy transducers and sensors
vibration and damping systems
robots and manipulators
mechatronic systems
manufacturing machinery
vehicles and transportation systems
power electronics
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2.2. Presentation of system dynamics
Multipole diagrams consist from graphical symbols
of multipole models of individual components of the
modelled real system. The symbols are interconnected by line segments representing energy
interactions between the real components. Each of
the line segments is associated with a pair of
conjugate variables the product of which expresses
the power transferred in the interaction. Interconnections of the line segments respect physical laws
governing the energy interactions.
Figure 1 shows examples of three different graphical
presentations of system dynamics exploited in
DynLAB. Movable 3D virtual-reality geometrical
models allow learners to investigate dynamic behaviour of the systems under study qualitatively. Plots
of system responses allow them to evaluate the
system behaviour quantitatively.
The multipole diagrams can consist from symbols of
twopoles like ‘pure’ resistors, capacitors, dampers as
well as from symbols of sophisticated multipole
models of complex real components like motors,
valves, amplifiers, etc. Learners have at their
disposal a large collection of multipole models of
different level of abstraction and idealisation for the
typical system components.
Topology of multipole diagrams is isomorphic with
the geometric configuration of the modelled real
systems. Thanks to this, the diagrams can be set up
in a kit-like way based on mere inspection of the real
systems in the same way in which the systems have
been assembled from their real components. There is
no need for forming any equation, a block diagram
or a bond graph. If necessary, however, the
multipole diagrams can be freely combined with
equations or block diagrams.
(a)
Using the multipole approach is also of several other
important advantages:
 multipole models can be developed, debugged,
tuned up and validated once for ever for the
individual subsystems independently of the rest
of the system, and once they are formed they
can be stored in submodel libraries to be used
any time later
 this job can be done for different types of
subsystems (e.g., fluid power devices, electronic
elements, electrical machines, mechanisms, etc.)
by specialists in the field
 behaviour of the individual submodels can be
represented by different descriptions each of
them suiting best to the related engineering
discipline or application (lagrangian equations
in mechanics, circuit diagrams in fluid power or
electronics, block diagrams in control, etc.)
 the submodel refinement or subsystem
replacement (e.g., replacement of an electrical
motor by a hydraulic one) can be taken into
account without interfering with the rest of the
system model
(b)
(c)
Fig.1: Robot: (a) 3D geometric model, (b) multipole
diagram, (c) plot of the robot-arm trajectory.
The plotted responses result from simulation of the
system dynamics. In DynLAB, such a simulation
exploits multipole models of system dynamics
represented graphically by multipole diagrams. As
these diagrams portray directly the configuration of
real systems, their set up is easy and straightforward.
2.3 Learning modes
Table 1 shows examples of learning modes used in
DynLAB.
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Table 1: Learning modes in DynLAB
Learning
objective
stirring up interest
in dynamics
Course assignment
Prerequisites
high-school
math and physics
Given
Task
3D virtual model
of a real system
to modify system parameters and excitation to
observe changes in its dynamic behaviour
introduction to
high-school
dynamic modelling math and physics
configuration of
a real system
to set up the corresponding multipole diagram
and to simulate its behaviour
more advanced
fundamentals of
dynamic modelling system dynamics
configuration of
a real system
to set up the multipole diagram from custommade submodels and to simulate its behaviour
formulation of
system equations
introduction to
configuration of
dynamic modelling a real system
to form corresponding equations and to solve
them, to set up the multipole diagram, and to
compare the solution with simulation results
introduction to
control design
formulation of
system equations
model of a plant & to reduce the model, to design control, and to
control objectives verify it using the plant unreduced model
introduction to
system design
introduction to
control design
system
specification
to design system configuration and to optimise
its parameters
design of virtual
experiments
advanced dynamic
modelling
experiment
specification
to design 3D virtual model, to set up the dynamic model, and to write the simulation script
2.2 Learning environment
3.
The DynLAB course is delivered within a Webbased learning environment supporting learners’
mutual collaboration and communication with their
tutor. The investigative way of learning is
encouraged by open problems and virtual
experiments. The course flexibility is achieved by its
modular arrangement with a number of different
entry points. In each module, the prerequisite
knowledge required for its study is clearly specified.
INTERNET-BASED TOOLS
3.1 Modelling, simulation and visualisation
DynLAB partners have developed a number of
innovative tools applicable to the project. one of
them is DYNAST – a software package for efficient
modelling, simulation and analysis of multidisciplinary systems. It consists of several software
components that can be installed either on a single
computer, or they can form a distributed system
interconnected by the Internet.
The course is accompanied by a large collection of
examples of various problems solved both in
academia and industry to imitate knowledge sharing
and informal learning typical for large organisations.
The examples can be resolved and modified in an
interactive way across the Internet. This gives the
learners a hands-on opportunity to acquire the
necessary skills in solving real-life problems.
The kernel of the package – DYNAST Solver – is
a tool for
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Organisational learning imitates knowledge sharing
and informal learning typical for large organisations. It is supported in DynLAB by a computerassisted ontology-based process in which knowledge
gained during solution of problems is captured,
recorded and later made available to learners ‘just in
time’ when it is relevant to the problems they are
supposed to solve.
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solving implicit sets of nonlinear algebrodifferential equations submitted in a natural
textual form
analysing nonlinear multipole diagrams that
may be combined with block diagrams or
equations and submitted in a graphical form
linearising the diagrams and providing their
semisymbolic analysis in the time- and
frequency-domains
In the case of multipole diagrams the underlying
equations are formulated automatically and then
solved by the DYNAST Solver. The Solver can be
accessed across the Internet in a Web-based, on-line
and e-mail modes as it is illustrated by figure 2.
Self-study is supported by interlacing the course
texts with self-assessed quizzes, tests and other
motivation elements. For the remote tutoring mode,
there is a collection of tutor-marked assignments in
each module.
Setting up the multipole and block diagrams in
a graphical form directly on the Web is enabled by
the schematic editor DYNCAD, a Java applet.
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Fig.2: Environment for modelling, simulation, virtual experiments, control design and publishing across
the Internet.
DYNCAD converts diagrams into textual files and
sends them across the Internet to DYNAST Solver
installed on a server. After the computational
results are sent back, they are plotted on the clientcomputer screen. Users can open their free private
accounts in DYNCAD and store their simulation
problems on the server. DYNCAD is also able to
convert the set-up diagrams into PostScript and
send them to users by e-mail.
3.2. Control design with MATLAB
MATLAB – the most popular control-design toolset
admits model descriptions in the form of block
diagrams or equations. These descriptions suit well
to the abstract and idealised models used in control
synthesis. Using them, however, for ‘virtual
prototyping’, i.e. for thorough control design verifications and for realistic dynamic studies, is too
laborious, cumbersome and error prone. Equations
describing the system model as well as a block
diagram representing the equations must be formed
manually before the block diagram can be
submitted to a computer. In addition, the blockdiagram-oriented simulators usually encounter
numerical problems with causality, algebraic loops,
changes of the equation order, etc.
DYNAST can be accessed in an even more
comfortable and user-friendly way via the on-line
mode. This mode requires, however, downloading
and installing working environment called
DYNSHELL on client computers with MS
Windows. This software has been designed to suit
to users of different levels of qualification and
experience. Dialog windows (wizards) allow for
submitting problems in an intuitive way without
learning any simulation language. All operations
are supported by a context sensitive help system,
and they are continuously checked by a built-in
syntax analyser. Dynamic diagrams can be
submitted in a graphical form using a built-in
schematic editor.
In DynLAB, learners use MATLAB neither for
simulation, nor for virtual experiments. They are
exploiting its advantages for control design,
however. The server-based DYNAST can
communicate with MATLAB control-design
toolsets installed on learners’ computers across the
Internet.
DYNAST Shell can also communicate across the
Internet with the LaTeX-based software package
for automated publishing reports on simulation
experiments. The documents can be published in
PostScript, PDF and HTML. The simulation results
can be also used for animation of 3D geometric
models of the simulated objects using VRML. The
learners need to download and install on their PCs
only the free CORTONA software.
Using either DYNCAD or DYNSHELL, the
dynamic-diagram model of a plant to be controlled
can be easily set up in a graphical form. DYNAST
can be then used to simulate the plant and to
validate its open-loop model. If the model is
nonlinear, DYNAST is capable of linearising it.
Then it can compute the required plant transferfunction poles and zeros, and export them to
MATLAB in an M-file. After designing an
analogue control within the MATLAB controldesign environment, the DYNAST model of the
plant can be augmented by the designed control
structure and thoroughly verified by DYNAST. As
an example, figure 3 shows closed-loop model of
the inverted pendulum problem specified in [4].
The procedure is described in more detail in [5].
Another very useful tool is the DYNAST Monitor.
Installed on computers of DynLAB tutors, it allows
them to observe the data files and diagrams
submitted by learners to DYNAST Solver. The
tutors can then help the learners to overcome their
eventual difficulties and discuss their problems.
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In the case of digital control, there is another option
for verification of the designed controlled system.
After designing the digital control using the
MATLAB control-design toolset, the resulting
control structure is implemented in Simulink
installed on the client computer while the
controlled-plant model remains in the remote
DYNAST as shown in figure 4. During the verification, Simulink communicates via its S-function
with DYNAST across the Internet at each time step.
REFERENCES
[1] Future Directions in Control Education,
special section in the IEEE Control Systems,
Vol. 19, No. 5, Oct. 1999).
[2] S. Dormido Bencomo: Control Learning:
Present and Future. b’02 IFAC Congress
plenary paper, Barcelona 2002
[3] IEEE Control Systems Society Technical
Committee on Computer Aided Control System
Design - http://www-er.robotic.dlr.de/cacsd/
CONCLUSIONS
The automated access analysis to the DynLAB
project website [5] clearly indicates that the tools
available on the server are utilised across the
Internet by visitors from all over the world. Their
number grows rapidly despite the fact that the
project outcomes are still in the development phase.
[4] Messner, B. and D. Tilbury. 2000. Control
Tutorials for MATLAB at
http://www.engin.umich.edu/group/ctm/
[5] Website of the DynLAB project at
http://icosym.cvut.cz/dynlab/
Fig. 3: Analogue PID pendulum control.
Fig. 4: Digital control of pendulum.
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