Vehicle manufacturers, operators and infra managers all have their piece of the puzzle when it comes to building digital twins of rail infrastructure or vehicle systems.
They also all have their own benefits of using these digital twins.
During the last Railtech in Utrecht, Ricardo Rail’s Ilse Vermeij, Jasper Peen and Gijs Vugts hosted a workshop on these questions.
But to start with, we need to make sure that we were talking about the same definition of a digital twin as this buzz-word has multiple meanings. In this blog, we mean with digital twin a virtual (simulated) copy of the real product, which is not the same as “just” a set of operational performance data. This virtual copy, or model, can be created based on theoretical behaviour of the systems or operational data (for instance by system identification). Before a digital twin can be used it is very important that proper model validation has taken place.
Such digital twins can be built on component level or based on the complete rail system with variable level of detail. Furthermore it is not necessarily fully digital, but it can also contain parts of the real world (creating a Hardware-in-the-Loop or HIL model). This can be especially useful for system integration testing.
If we look at trains and infrastructure, digital twins can have a benefit in all phases of the life cycle, as shown in the picture below.
The reason to use digital twins often has to do with reduction of risks, reduction of cost, better prediction and planning or better collaboration. Building Information Modelling (BIM) is a great example of a way to facilitate the design process in case many different parties are involved. However, the model created during the design and build phase, is also very valuable during the operation and maintenance phase, opening a range of possibilities for technologies like augmented and virtual reality.
In the railway branch, often models are created by operators, infra managers and manufacturers, but they hardly share these models. Probably due to the fact that sharing models is considered to be risky regarding intellectual property on the one hand and on the other hand because there is a lack of awareness, not only of the existence of these models but also for the potential benefits other parties can have of using the models. Regarding the latter we have provided an example below, showing the benefits of sharing multi-body digital twins between the three parties mentioned.
One clear example of our day-to-day experience concerns the use of multi-body dynamic models. These models are used as a digital twin to simulate dynamic interaction between rolling stock and infrastructure. Such a model can be very useful in the specification and design phase of a vehicle or vehicle component. After the design phase it can be used for virtual certification, since new standards in like EN14363 specific situations allow the use of such models instead of expensive and complex physical test runs on track. In the operational phase of rolling stock, an operator can make use of such a model to investigate passenger comfort or look for improvements in the wheel/rail interaction to reduce costs. But even an infrastructure manager has benefits if he can use such a model to assess track quality based on vehicle reactions. An example of such an application is Ricardo’s innovative track geometry assessment tool Pupil.
In our opinion this shows that multiple stakeholders can make use of the same Digital Twin for distinct purposes, each out of the perspective of their specific roles. However cooperation is needed to effectuate these benefits for all parties.
But issues about intellectual property and confidentiality are difficult to resolve. About the same goes for financing, who is going to invest in such a Digital Twin?
An interesting idea suggested, is to initiate overarching bodies in the sector that invest in digital twins which are available for all stakeholders. And regarding the intellectual property challenge you should be aware that there are multiple ways to share models. Apart from sharing the complete model, with all information visible, it is also possible to share a black-box version of the model or just share the output. Which method fits best depends on the situation. It is in any way important when sharing a model (or digital twin) you make clear what the interfaces are (input and output) and what the model can be used for.
In our vision the use of Digital Twins will be more and more state of the art and relevant, but it is important to search for better ways to collaborate in these developments.
This article was originally published by Ricardo Rail.
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