We have a very interesting business case, we have the same issue at the SNCF and I am very
happy that my just presented today.
Yes, thank you, Lovic.
So I will give you a bit of an insight on how to process the GNSS position of a train.
I hope everybody knows a little bit what the GNSS position is.
You can think of it as GPS, but in a more general fashion.
So you can also follow this presentation live with this QR code and let me first introduce
myself.
And Mattias, I worked for 15 years in Inferable, and my last day was Friday.
Sorry, I don't know, not sure if that's appropriate.
But yeah, I'm not become a data freelancer, real-way data freelancer, so if anybody is
looking for one.
I really like linked data, that's why I've put this on the slide, linked data, semantic web or
the F, this kind of thing.
And I've been working for Inferable.
So actually I didn't really dare to put the punctuality number on it, but there are a couple
of other numbers, how total punctuality is more as NCB problems than Inferable.
So we have lots of tracks.
Now if you compare numbers of kilometer of track, then sometimes it's confusing, because
I think the Swiss mentioned double track, and here is the total track.
In Main Track, because if you count as well the side tracks, then you have lots more, so
it's difficult to compare the numbers if you don't have a good semantics, of course.
And yeah, we are also getting famous for our deployment of ETCS in Europe.
So almost all the Main Track are equipped with a signaling system from European standard,
ETCS stands for European train control system.
And a lot of people that work at Eferable are actually quite open source minded.
One of them is organizing for them, but the company itself has not yet that open source minded,
but I'm glad to be able to announce that since last year, we are also a partner at open rail.
So I'm quite happy to say that at this conference.
And we are not yet open source minded, but we do have a very big open data platform that's been there for a couple of years.
So feel free to browse in the data sets.
I read this morning, and I said, I'm so happy I need to put this on a slide and present it to you as well.
Peter Colpart is a professor at at the University of Gantt.
He posted this this morning, and he said, okay, I read through the government agreement.
Yes, Belgium almost has a government.
And he says, okay, it is really good for our open data.
And I was very happy because open data is very nice, but it's also very good for open linked data.
And it's also mentioned in the government agreement.
So if you don't know what it is, I would suggest to look it up and to gain some skills in that area.
And if you would like some pointers, then feel free to come to me after the presentation.
So back to on track, back on the topic.
Why do we need to do this thing with post processing positions?
Well, we have this measurement vehicles, and we need them to go measure the tracks and see if they are still in the correct position.
If they are not in wrong with them, something that we need to intervene in.
So they drive around everywhere in the network.
And yeah, if you want to process that, you need a position, you need to put it on a chart.
And then detect the issues and send a correct position to your technicians to go fix the issue.
And if you want to do some predictive maintenance, so that means I want to see what happened last year,
and the year before, and then the year before, and that's a kind of short timeline.
Well, yes, you can do that, but for a specific position, if it's wrong in a meter,
last year a meter to that side, and then the next year a meter to that side, it can get a problem.
So you need a very accurate position in order to do a trend line analysis.
And it can get quite complicated.
Lots of switches, lots of tracks.
So what tools do we have?
Where we have this measurement train?
Well, the first thing you do is you install a GPS system on it GNSS receiver.
And you try to make this as precise as possible in real time.
You try to get some corrections happening, and that is what's RTK stands for.
It's actually very simple RTK.
You put a GPS somewhere, and you measure very precisely the position of that location.
And at the same time, you're going to see what the singles say of your GPS satellites,
or they say I'm okay, I'm a meter away, but that's not true, I know I'm here.
So the correction needs to be a meter in that direction.
So that's the kind of correction you can do with a GPS.
But one issue is you need to have some sky, some clear sky.
It doesn't need to be perfect all the time, but if you have lots of buildings,
and a tunnel, and so on, then it can get quite complicated.
I have a question, but the people, for me, for a bell that they are sitting here cannot answer.
I didn't ask my question yet, but you already gave me this question.
So I was going to ask the question, what is the difference between UTC time and GPS time,
and I got the right response over there? Do you know the number of leap seconds?
Yes, it's 18, so about 20, yes.
Well, I can guarantee you if you're making some kind of system that post-processes GPS data,
and you need to link it to images or other measurements, and they don't line due to this,
due to you not knowing that there are leap seconds, then you can get very confused,
and takes a lot of time to try to fix it.
And some people need to do it a second time.
Secondly, we have another tool that helps us to do positioning,
and that is more relative-based positioning.
So if we are in that tunnel, and we don't have a clear sky,
well, we can still remember our last position, and try to measure the changes in direction that we have.
And that is the EMU, IMU, inertial measurement unit, it's an accelerometer, a very expensive accelerometer.
And the more expensive you go, the more precise it is, and the more precise it is,
the longer you can travel in a tunnel without too much of an error.
Because it's relative, the smallest error you have,
well, the longer you go without anything that fixes the error, the bigger the error.
So, and the second thing that we can use is an automator,
that's everybody knows what it is.
Yes, it's the wheel. So, you will turn, and you measure the distance that you travel.
Every car has it to display the speed as well, and we also use that for positioning.
Oh yeah, and a normal GNSS receiver, you can actually just plug and play, plug everything in,
and it will use all these things that I just mentioned, to calculate a very precise absolute location.
A third thing, since we are in real-way, in the TREX, we have these boxes,
or we have crocodiles or other boxes, they detect trains, and the train can also use them
to detect where it is, because if you have a database that has these IDs of these objects,
and you pass over it, then you know for sure, okay, I'm over there.
So, that's the third thing that we can use in order to improve positioning.
So, absolute relative and detection systems, what are we going to do with all of that? We are going to
give it an information, at least, at our almost open-source train positioning library.
So, we gather the data, we put it into that library, it starts working, and it gives us a
track position at the end. A topological position, you have heard the word a couple of times before
topology, well here we also going to use topology, but not on the micro level where your stations
as notes, but on a micro level, the smallest level switches and trails.
And yeah, it's not yet open-source, because it's actually a lot more work than you would think,
if something was close source, in order to make it open-source, it's a little bit more work
than you would think before. So, let's see, we have a train driving on track A,
and in that direction to the left. And the blue points are the GPS coordinates that our GPS
receiver is outputting. As you can see, there is already a bit of an error, and there is a switch
in the middle. Now, let me first simplify a little bit this visualization. Let me combine both rails
into one, to have this as a more schematic design with a center axle axis of the track.
And well, what can we do to now post-process the coordinates?
The first thing, the most simplest idea we can do is we can say, okay, let's just project
those blue dots onto the closest track. And then we would get this result, the green dots.
And as you can see, in the switch, it's not very good, because, well, yeah, we kind of jump
a train from one track to the other. It needs to take a switch, a proper way,
or you would need to have a lot of willing passengers on the train to lift it up and put it on.
And we all know that in Belgium, passengers are horrible.
So, let's work the problem with a bit further. Welcome navigability. So, we heard the topic before
topology. Well, here topology, we have also notes the switches and things that connect
switches and tracks trails. And you cannot go from one trail to the other just by that. So,
you cannot go from A2 to S1 without passing by A1 and then reversing direction.
So, we can get this graph, this connectivity graph, and we can use that in our navigation
system, in our post processing system. So, applying this principle,
gets us that the green dots are where they need to be. So, we are happy. Right?
Not yet. Maybe if we go in the other direction, we will have a problem. So, if the train is driving
the other direction, then the navigability is going to give us more issues. So, it's so right,
we can use it, we can get a separate, but it's not yet perfect. So, let's see what we can do with
those beacons, train detection systems. This is a typical view of a traffic operator.
And it's topological. So, you see that the switches are there and you see the trains running.
So, the red is in fact the current location of a train and the green is the plant route that the
train will take. So, this information exists, this is available at least inside our company.
So, we can use it to improve the location a little bit better. So, that's actually what's
that train positioning library is is doing. It will first calculate the train path.
It will first try to find and optimize the way that a train run. And then after that, after we
figure out the train path, then we will go project the GPS coordinates onto it.
And we do that with whatever data is available. So, if at a certain point we don't have
information about a single-ing system, then we can use the GPS locations as well to calculate a
train path. And any gaps that exist, well, some of them are easy to solve. So, from here,
if you have a train running on the red line over there and you also have a detection over here,
well, you don't need to be psychic to know that a train probably went in this direction.
And the same goes for this trail. It was missing in the train detection system.
Noting is perfect. Rest assured, the signaling system is perfect. You will not get any accidents,
but the data behind it is not always the logging data is not always so precise.
But then on the other side, over here, it's a bit more complicated. You will need some additional
data to actually know what the train has done. Although we can be quite sure, looking at that,
it just goes straight ahead. But you never know if info about those works over there and then
reroute the train. Okay, so, for them, 2023. First time this railway track was organized
and at the time RCMDX was presented and was made open source. RCMDX is rail condition monitoring,
data exchange. It's an exchange format. Very interesting. If you ever want to exchange
data in a very compact way, a binary way, look it up. And at the time I said, okay,
info bell will join SBB who introduced RCMDX in the project and we will try to implement it as well.
At the moment, one possible extension of the project of the train positioning library could be
to read and write to that RCMDX file. So, it's the file that is transmitted off the measurement
train. It's that contains the raw data and then we can say, okay, we put that library besides it
and we're going to take the data out, process it and put it back in. And then you still have
a standard format to exchange your data. And at the same time, well, all the topology data that
I talked about that you would need for the train positioning library. Well, you could also imagine
a connector with something like Rint. Rint is the register of infrastructure. It's one of those
TSI things that we heard before, as well, the moment TSI telemetics. All those TSI's have data requirements
and Rint is one of those products that combine all the data. Rint will be hopefully next year,
database which is in linked data as well, which is complete of micro topology information from all
inform managers. So, it's going to be a very important source of data, also for projects like these.
And to wrap up, I, in my description of the project, I also promised to give you a little bit
of an insight on how we also use open source hardware and information. So, in a measurement train,
you usually have some of the driving the train, but also somebody who is going to push the buttons
to say, okay, now the measurement system needs to be turned on. Now we are driving this direction
on this line as well. We automated all of that for the positioning system. So, the positioning
measurement system. And we did that with the Raspberry Pi. It's very simple with some shell
scripts, actually, not really, we didn't even use Python for it. And it's, it worked flawlessly
until at one time it became a black lump of silicon when some safety transformer burnt out.
And yeah, but that's not the issue of the Raspberry Pi.
And yeah, that's to prove. And this is a picture of the cabinet where it's in. And yeah,
you can see it's in, hello over there. There is a shield on it to connect it to other
sources as well. So, thank you very much for listening.
And if you have some questions, I'll be happy to answer them.
Okay, so the question is will it be open sourced? Yes, it will. That has been decided. It's part
of the reason why, well, if we're about joined open rail and now we have to put some, we need to
eat a pudding, putting as well, of course, we need to join the community and give something back.
And yes, some people might be, other people might be able to tell when it's going to happen.
But I hope that it would have been before this day, but it has a bit of delay, which is not normal for
trains.
Yes? Yes? How did you get around regulatory or threat tape making it's called threat
very high in the country? Because I have heard those, they're very self-acquisited.
And often the hardware is very ancient and very crappy because of all the threat tape
to glory, years and very expensive clarification. So, I'll put it get around that.
That's a very good question. So, how did we get around to the threat tape involving installing a
Raspberry Pi on a measurement train?
Next question.
I think a large problem because it doesn't do it in the passenger train, so it's okay.
This is safety. That's why it's.
Yeah, it's all the safety components, but you also have fire regulations as on that might apply.
Does it have its own power supply? It's connected to a power converter, USB converter, let's say,
inside the cabinet. Well, it's not USB plug. It's a real transformer meant for the railway vehicles,
of course, yeah, which out with five volts, 25, 24, 12 and so on.
Those are really signaling begins. So, they are part of the signaling system, they are connected to the
signals and to the interlocking. And yeah, it's, I'm not sure what the transmission
technology is. It's not like once they're using the tunnel and they're either to the train,
if it's used. It's very, yeah. Well, no, but it's at the 27 megahertz. So, get your SDR on.
Yeah.
Well, and so the question is, if, when we travel over a beacon, do we get a precise position from the beacon?
Or do we know the precise moment that the train travels across the beacon?
Do we know the precise moment that train traveled over the beacon?
For this project, it's not important. But we do know that precise moment, but you can also
refresh the question a bit. And the problem with the question is, your detection system of the beacon
is somewhere under the train and it's not at the same place as the GPS antenna. So, you will need
to take into account that distance and the speed that you're driving and the orientation of your vehicle
in order to figure out to place at the time. But in this case, the exact position in the
longitudinal sense is not so important. It's knowing on which track you are or trail you are,
that is important.
Just mention the TECA system, after TECA system, and you just talk about the genesis system,
did you try the TECA which is very precise?
Sorry. So, the question is, we use GNSS and RTK, and which is more precise?
So, adding RTK to a GNSS solution, you first need GNSS and then you can add RTK and it will improve
your positioning because it will decrease the environmental issues that you have with GNSS.
So, if you, I explained before that RTK works by having a base station, somewhere near where
you're measuring and that base station is most exactly its location. But it's also measuring
the GPS signals and can then say, okay, the GPS signal that we get are distorted in this way
and then you can add corrections. The precise position of your measurement vehicle will depend
on more than just adding RTK to improve the solution you, if you're in a tunnel or in an area
with trees or some overhead constructions, then you have more distortions than the base station
you will see as distortions. So, you will not be able to correct for those.
Yeah, but adding RTK is always a good idea. It's in Belgium, it's free. You have,
well, it depends on how you use it. But you have flapples, well-core, if people wonder
and see that at the same time, info about things about building its own RTK network
to then be able to sell it to ZNCB. Yeah, it's more for the safety, the people that work that we are
going to, info about is also busy but improving worker safety and one of the things that they want
to improve on is alerting people when they are going inside the dangerous area and that is
by GPS taking the people and adding RTK is helping making it more precise. Okay, I see my time is up
so if there are any more questions and please feel free later.