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Thread: Track and Inertial Modelling

  1. #1

    Default Track and Inertial Modelling

    Hi All,

    I am working on a project where I want to get the inertial output of a train moving along a realistic track, and I am hoping that Open Rails can provide this. I've tried to have a look through the source code, but I'm not finding it that easy to follow.

    Can someone please explain to me the data structure that is used to store the model of the tracks? Or point me to some relevant documentation?

    I am hoping that the track models include the inclination of the track, pitch, roll, etc. As I would like to get inertial data for a train as it is banking on an inclined track. Does anyone know if this is possible and how I would go about doing this?

    Also, I can't determine what inertial data is available for the train, is their a virtual IMU somewhere in the simulator? What data can it provide, and how can I get at it. If somone knows which files in the source code this is in, and can recommend some useful documentation that would be great.

    Cheers,
    -Steve
    Last edited by StevenSam; 10-20-2015 at 12:11 PM.

  2. #2

    Default

    This is not a subject which can be discussed in a few sentences to an apparent newbie and apart from having expert knowledge of creating graphic objects with 3ds MAX, etc, it will take years to learn how to create tracks for MSTS !

    You can look into MSTS Shapes files with a suitable editor that can show their contents in plain English, but what it all means is another ball game !

    Try and learn about what it takes by doing some research with GOOGLE, because there is nobody left in this forum who can do all of what you are planning to do !

  3. #3
    Join Date
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    Default

    Otto, your entire response presumes an awful lot about not only the person asking for information but also exactly what information he is seeking and also your assumption that nobody here can be of assistance.
    IBM XT i386; 512Kb RAM; 5.25" FDD; 1.4Mb FDD; 5Mb HDD; VGA 256-colour graphics card; AdLib soundcard; DR DOS 6.0; Windows 3.0

  4. #4

    Default

    Hi Guys,

    Thanks for your responses, but perhaps I have not conveyed what I am asking very well.

    I'm not interested in the graphical modelling of a track, and I am not trying to create my own track.

    I am atrying to understand the underlying data structure that represents a track model, and specifically I want to know if it stores data on the pitch and roll of the track. Does anyone know if it does?

    I've had a look at the source code, and within TDBFile.cs, there is a TrackDB class which seems to consist of an array fo TrNodes and TrItems, however this doesn't really give much detail and I would assume that there is much more complexity than this. I have of course spent some time searhing through Google, but this doesn't seem to be covered anywhere that I can find, so I though I'd ask the experts.

    Another way of looking at this, is if I were to write my own program to load track files, what would I need to know?


    The other part of what I am asking is if there is a simulated IMU in the train. I would like to tap into multideimensional acceleration and angular acceleration data for the train if it exists. So, does anyone know if this does exist, and if so where it is in the source code. I would assume that there is some rigid body physics modelling that starts from torque/force and integrates up to determine accelerations, velocities etc. I'd like to find and understand the code that does this.

    When I posted this question, I was assuming that this forum is used by developers who understand the open source codebase, and if so I would have thought that there are some people here who can answer my questions, or at least point me in the right direction.

    If not, can you suggest somewhere else I can look for this informations?

    Cheers,
    -Steve

    I am

  5. #5
    Join Date
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    Open Rails is not yet that sophisticated. It started life as a project to utilise MSTS routes and equipment and as such had no need for That type of code. MSTS track is all flat, even on curves. The track positional data is held in the MSTS route tdb file. Position on the track is handled by a 'traveller' which follows the database. Far as I am aware, Open Rails does not model inertia, only resistance.
    Beer is not a matter of life or death, it is much more serious than that.

  6. #6

    Default

    Thanks Baldwin,

    I had assumed that the velocity and position of the train was based on a physical model that would use the mass and moment of inertia of the carriages along with the motor torque or force to calculate linear/agular acceleration, and integtrate up to find velocities and positions. Are yous sure that this is not the case?

    Can you provide a little more detail about how the 'traveller' follows the track database. A link to a relevant document, or the sections of the source code that handles this would be great, as my Googling hasn't turned up very much.

    Cheers,
    -Steve

  7. #7

    Default Track and Inertial Modelling

    Inclination, pitch and roll are incorporated into the data model using quaternions, which in turn get converted into vectors for the traveler to follow.

    If you want to get more in depth on the application, join the forums at ElvasTower.com as that's where the development team members congregate.

    A few team members participate here as well, and there are also some power users here who understand how the physics model and track/world models interact, but this site tends to be more of an end-user and content builder audience.
    Last edited by eolesen; 10-21-2015 at 06:51 AM.

  8. #8

    Default

    Thanks,

    I've just tried to have a look at ElvasTower.com, but they are not accepting new members, so it's out of reach for me.

  9. #9
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    If you are thinking of the track superelevation and the cab 'vibration' they are very elementary models. there is nothing that I am aware of that would actually generate the required sideways, forwards or backwards inertia. Yes it will generate a curve speed warning if that is turned on, but actual inertia, I think not.
    Beer is not a matter of life or death, it is much more serious than that.

  10. #10

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    @Eolesen. When you say that inclination is in the model, is this the inclination of the track, train or both?

    Are there any other sources of information I could look into as I can't access ElvasTower?

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