Cyber-physical systems (CPS) are very large systems that not only involve
a large number of stakeholders but are safety critical and have significant impact on the economy and the
environment as well. This makes tools for the safe and efficient design and operation of such systems
imperative. The ITEA project MODRIO, which ran from 2012 to 2016, was set
up to extend modelling and simulation tools based on open standards (Modelica and FMI) from system design to
system operation.
Integrated modelling and simulation framework
The main technological ambition of the project was to provide an integrated modelling and simulation
framework able to efficiently specify, design and operate CPS. To that end, new ideas were developed to
address the complete engineering lifecycle, from preliminary design to operation and maintenance. New
features include the formal modelling of requirements involving objects, sub-systems, systems and human
interactions in space and time in order to automate system design verifications.
With optimisation of the operation of large transients such as start-ups or shutdowns or the evaluation of
the consequences of faults and failures in mind, a new modelling approach was developed. The aim was to
provide the ability to simulate the system behaviour away from its nominal operating point when transitions
between modes, represented by completely different sets of equations, take place. For the safe and efficient
systems operation, techniques used for weather prediction, known as data assimilation, were adapted to CPS
in order to evaluate the system state, in real-time for predictive control or with the error margins for
system diagnosis. The stochastic aspects of CPS were also taken into account by associating in the same
framework probabilistic methods (such as fault-trees) with deterministic modelling and simulation.
Key success factors
A key success factor for this project was the involvement of large industrials whose businesses are to design
and operate large CPS in four major industrial domains: Energy (electricity production, transmission and
distribution), Aerospace (civil aircraft), Transportation (trains) and Buildings. The industrials ensured
that the project was always on the right track by providing requirements constantly updated to the
industries real needs, which are rapidly changing because of environmental concerns and harsh economic
competition, and by validating the results of the project against real-life demonstrators.
Another key factor for success was to base tool development on two existing standards, Modelica and the FMI,
whose properties of being already mature for industrial exploitation and yet still sufficiently flexible to
be adapted to the problems at hand fitted the bill. The fact that all prominent players in the MODRIO
project participated in those two standards, in terms of standard and tool development, was also a major
reason for success.
Last, but not least, the project benefited from the cooperation between SMEs and research organisations. The
latter developed new methods to solve the difficult scientific and technological problems related to the
modelling and simulation of CPS, handing over the results to the former to be implemented in a wide range of
commercial and open source tools covering nearly all aspects of physical modelling and simulation at the
system level: Energy performance simulation for buildings (Sherpa Engineering), IDA ICE (EQUA Simulation
AB), JModelica.org (Modelon AB), SimulationX (ESI ITI GmbH), Triphase (Triphase), Wolfram SystemModeler and
OPCClassic (Wolfram MathCore AB). Having the OPCClassic Modelica library as part of Wolfram’s offering has
been an important enabler for them to broaden their scope on process industry projects. After the MODRIO
project, they have taken on a number of public funded research projects and consultancy projects within the
process industry domain which, in term, has led to the development of their OPCUA Modelica library that
further strengthens their modelling and simulation platform in the process industry domain.
Results were also implemented in tools from larger organisations such as Dymola (Dassault Systèmes), LMS
Imagine.Lab Amesim and LMS Virtual.Lab Motion (Siemens), O3PRM editor (EDF), OpenModelica (Linköping
University), PySimulator FMI 2.0 (DLR), Simpack (Dassault Systèmes) and xMOD (IFPEN).
Power of exploitation
The project results have been exploited in numerous ways, starting while the project was still in
progress. One of the main early achievements was the ability to generate software code for
optimising the control of almost one tenth of German electrical power production. Since August
2015, OpenModelica has been used in ABB’s product Optimax Powerfit to generate optimising
control code that controls and coordinates about 5000 MW (ca 7.5%) of German electricity
production within seconds. This has subsequently been expanded to about 6000 MW. Up to 1500 MW
comes from more than 2500 small solar and wind power generators that are coordinated to operate
as a single big power plant.
As another example of early achievement, Vattenfall used the results to optimise the start-up of
conventional power plants, with an estimated yearly gain of €850k per plant. Such optimisation
is being made necessary by the rising share of renewable energy production that forces
conventional power plants to manoeuvre more frequently to balance the grid, while complying with
all operational constraints in order to meet safety and environmental regulations and minimise
system wear.
R&D projects,
in particular ITEA ones, helped in creating or enhancing new capabilities from quite low TRL in
particular domains to levels which now allow industrial use of these promising technologies
For Dassault-Aviation, MODRIO has enabled many very
useful breakthroughs for the design of
next-generation aircrafts, in particular the results regarding the modelling of requirements and
system architecture, associated with fast multi-core simulations, multi-mode modelling of system
failures and safety analysis. Outputs from ITEA projects brought Dassault-Aviation capabilities
allowing working differently, in a more global capabilities to handle complex systems; which
takes part of the global (digital) transformation of the company.
In the rail domain, the industrial cooperation partners – Knorr-Bremse and Bombardier
Transportation – focused the results on crosswind stability and friction brakes, where there is
high economic potential once the brake distance management has become adequately reliable. To
raise the potential of brake distance management, Knorr-Bremse uses FMIs extensively to share
simulation models between the stakeholders. This makes it possible to simulate the behaviour of
the entire system of a passenger train in a very early stage of development. As a consequence,
the newly developed braking systems allows Knorr-Bremse to reduce by 30% the hardware tests,
which in general are very resource consuming. In addition, the safety margins between trains can
be smaller with this braking system and thus more efficient usage of the track and better flow
of trains - between 5-14%, depending on the type of traffic - and passengers can be
achieved.
In the area of connected driving, the simulation of autonomous vehicles and ADAS (Advanced Driver
Assistance Systems) has been enhanced through a City Traffic Modelica Library. A combined
multiple-shooting and collocation optimisation method was further developed for efficient
solution of complex optimal control problems by TU Ilmenau. A student team of TU Ilmenau applied
this method in the framework of model predictive control to the autonomous driving Audi Q2 cars
in connection with another software environment (ADTF), winning 1st prize in the Audi Autonomous
Driving Cup 2017 and 3rd prize in 2018.
In the building sector, EQUA Simulation AB created the only building monitoring tool (the IDA ICE
Building Tracker) that leverages the information collected by the numerous sensors installed in
modern buildings to provide unique diagnostic capabilities. Many, very diverse, customers
already have shown strong interest in the IDA ICE Building Tracker. Currently, EQUA Simulation
AB is in the process of building prototype projects; discussions are ongoing for an office
building in Austria, an airport in Germany, and a multi-family residential building in
Sweden.
From the start of the Modelica initiative, DLR-SR has used Modelica models directly in
controllers, with the considerable benefit that non-linear models of the systems can be used in
the controllers with acceptable design effort, enabling the controllers potentially to cover
large operating regions. A key technique here is the so-called inverse model approach, where an
inverted non-linear plant model is used in the control system. Modelica, with Modelica tools,
allows such systems to be described and handled in a simulation environment. However, generating
code from Modelica models on controller hardware is not simple. The MODRIO
project now makes
this technique also available for non-specialists.
These different exploitation examples show how the MODRIO
framework can accommodate the different
stakeholders of the European energy system, paving the way for closer cooperation to tackle the
challenges of the energy transition.
Enduring impact
A few years after its completion, the project impact is still strong. EDF uses results regarding
the modelling of requirements to automate the FMEA (Failure Modes, Effects and Criticality
Analysis) of safety critical systems. Because the cost of modifications grows exponentially
while going further into detailed design, the benefit is the ability to perform safety
verifications all along the engineering lifecycle in order to correct design errors as early as
possible and avoid costly late modifications. The expected gains are estimated to be around 30%
of the cost of large projects.
EDF uses results regarding state estimation to detect and diagnose the causes of power losses in
power plants. A new power loss monitoring system, which combines physical modelling with
Modelica and Bayesian networks and modelling based on neural patterns, is now deployed in EDF's
nuclear power plant fleet, and has prompted the launch of a new start-up to provide model-based
smart diagnosis and prognosis services for CPS.
The newly developed braking systems allows
Knorr-Bremse to reduce the hardware tests by 30%.
The 1D and 3D real-time models originating from MODRIO
are being used by Siemens Industry
Software NV as building blocks in human-in-theloop simulators (car, motorcycle, aircraft), and
in Virtual Sensing (getting more out of measured data thanks to models), a joint research line
with KU Leuven that has become a leading R&D area, with the elaboration of numerous
applications. For Siemens Industry Software NV, the FMI/FMU is the cornerstone for recent and
future developments of the Executable Digital Twin (xDT): part of a model is exported as an FMU,
the rest of the structure is available physically and tested. This is also called Model- Based
Testing (MBT). For running models on a real-time platform, the FMI/FMU has confirmed itself as
the leading technology. ModeliScale, an ongoing French funded project that aims at scaling up
Modelica to very large systems, uses results regarding multi-mode modelling and state
estimation.
EMBrACE is a recently labelled ITEA 3 project in which 45 organisations across 8 countries aim to
develop a new standard and associated tools for the formal modelling and simulation of
requirements. The roots of EMBrACE can be found in MODRIO that produced
the draft specifications
for a new requirement modelling language called FORM-L adapted for CPS.
Finally, ideas developed in MODRIO about multi-mode
modelling were among the incentives to launch
the development of a new modelling language, named MODIA by Modelica founders, that could be the
successor to the Modelica language in the long term.
Dassault-Aviation states “R&D projects, in particular ITEA ones, helped in creating or
enhancing new capabilities from quite low TRL in particular domains to levels which now allow
industrial use of these promising technologies, but at the beginning difficult to implement.
ITEA projects have allowed to gather skilled partners to tackle the problem, on the base of
industrial needs provided by companies like Dassault Aviation, EDF ...”
More information
https://itea3.org/project/modrio.html
