Car Physics Modding for dummies.....

Discussion in 'Car Modding' started by Autosport, May 19, 2017.

  1. Autosport

    Autosport Registered

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    Hi Everyone,
    I've been lurking around the various Sim racing forums far a few weeks trying to get my head around rfactor2 modding and I've had a lot of headaches doing so, but I think things are starting to become a little bit clearer.

    There's very little in the way of step by step "Dummies" guides or how to videos etc on even the most basic of operations in this area. For example just being able to fire up Ptool seems to be a secret. So I'm thinking of helping solve these basic issues for others like me by doing some guides for other dummies.

    My background is as a Designer for various Formula One and other racing teams, suspension systems in particular. I'm currently a senior engineer for one of the BTCC teams, and have built a SIM rig to aid driver and car development.

    I've still got a million and one things to learn about how to do physics mods and get them working although I seem to have got my head around quite a lot of the Physics calculator spread sheet, there are still a lot of unanswered questions to get these mods to actually run on the game properly.

    I've felt and seem some glaring errors in a lot of the cars I've been playing with so far especially the Honda and Chevrolet BTCC cars, where the steering feel is weird and the physics files are full of odd values, but, I'm not yet at the stage where I can successfully manage to modify them and then get them to run again in the game.

    Is there anyone on here that would like to work with me to put together a "dummies" guide to this stuff to make it easier for other people to get involved with this side of Rfactor2?

    Darren
     
  2. Woodee

    Woodee Registered

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    A few people have set up a Discord channel to discuss physics and things... might be worth a look? https://discord.gg/h3xMxAD
     
  3. SPASKIS

    SPASKIS Registered

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    Very interesting to see professional racing engineers interested in improving vehicle physics.

    Regarding FFB, are you able to collect measured data? I understand that measuring torque in the steering shaft could be possible by means of strain gauges. However, I am not sure if this type of info is only interesting for FFB validation (correlation) or is a common thing to be included when gathering telemetry data. Thanks in advance.
     
  4. Autosport

    Autosport Registered

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    Thanks guys, the Discord thing sounded interesting but I'm new to that and couldn't make my way around it and where the conversations started, I need to spend some more time on that.

    The steering issues and making them feel right are more basic at the moment than trying to match the real car. We can at some stage log the car but at the moment the rf model understeers at very little lock in all conditions suggesting the modelling of the tyres and/or the suspension/steering is incorrect.
     
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  5. Woodee

    Woodee Registered

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    Discord is kind of like a realtime chat room so you can pop in and out as you see fit. You can either install the Discord App (PC or mobile) or use an internet browser.
     
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  6. SPASKIS

    SPASKIS Registered

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    Civic has been updated recently. Are you referring to old v1.08 version, newest v1.30 or both?
    https://forum.studio-397.com/index.php?threads/honda-civic-btcc-v1-3-observations.55619/
     
  7. Autosport

    Autosport Registered

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    I'd have to check but I believe it's the latest model. The Cruze model seems to refer to the Civic in a lot of the files and some of the figures are a long way from the real car, track width, suspension geometry, and wheelbase for example. I can't tell with the new Civic model as the files are locked.
     
  8. SPASKIS

    SPASKIS Registered

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    Considering you mention Cruze, you are probably referring to older model. I don't think the guys that made the Cruze for WTCC mod have updated with latest Civic physics (last week update). As you say Cruze had many if not the complete Civic physics.

    However, Cruze is 3rdparty and not an official rF2 car.
     
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  9. Emery

    Emery Registered

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    Not the latest Civic physics model in the Cruze. Agree with Spaskis.
     
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  10. Autosport

    Autosport Registered

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    An example of a confusing piece for me at the moment (Cruze files)

    [FRONTLEFT]
    BumpTravel=-0.0
    ReboundTravel=-0.125

    Does that mean 0 travel in bump?

    LeftWheelBase=0.0
    RightWheelBase=0.0

    Zero wheelbase either side?

    Kind regards,
    Darren
     
  11. Lazza

    Lazza Registered

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    Refer to the devmode skip barber files, they are mostly commented and will give you a lot of pointers.
     
  12. davehenrie

    davehenrie Registered

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    On many of the values, if they are set to zero, then the program defaults to the 3d model. As far as the bump travel, that may combine with other parts of the suspension file. I haven't dug into the rF2 files at all, so I don't know what has changed over the years.
     
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  13. lordpantsington

    lordpantsington Registered

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    Specifically:
    The travels are defined at zero ride height, as the distance the wheel can move vertically until it contacts the bumpstop. Thus at 0 ride height the bumpstop is just contacted and the wheel can move ~125 mm down in full extension. As you add ride height the available travel changes. For instance, if you set the car's RH to 60 mm, you now have 60 mm before the stop is contacted and ~65 mm is available for extension.

    Some things in the HDV are overrides, *WheelBase entries are some of those.

    Generally:
    You can find info about what rF wants for input in a couple of ways, In my modding infancy, I would routinely examine what comments ISI put into the files, across a variety of their mods. This is more difficult in rF2 because some OEM require the physics data to be locked in order to be licensed. IIRC the skip barber car in Devmode should be a good example to look at.

    Google is actually better for searching for specific entries, rather than the forum search. I couldn't get forum search results further back than 2015, and much of the good info/discussion came from the archives of the ISI forum. rf2 is built on a base of rf1 and knowing how that works/what it wants will provide considerable insight when you need to take a best guess at it. To better understand that I suggest looking for the guides by W_Bradshaw, they are all titled The ___ file and its role... I believe they've been copied into the wiki. http://wiki.rfactor.net/index.php?title=Modding_Information
     
    Last edited: May 20, 2017
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  14. Autosport

    Autosport Registered

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    Thanks everyone, very useful advice!
     
  15. cosm1

    cosm1 Registered

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    @Autosport I suggest to take a look to the Dev Corner here https://www.studio-397.com/modding-resources/
    The rF2 Physics Calculator is a big help, and for a quick reference just go to the skipbarber in dev mode and you will find the comments on each file.
    Maybe I will upload some old tutorial about the hdv and other files from f1challenge (still good for many things)
     
  16. Jokeri

    Jokeri Registered

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    @Autosport
    If you are a person who likes to pass knowledge on, please try to get the discord to work and join the group that Woodee linked (https://discord.gg/h3xMxAD) and contact Miro . @Miro is leading a project how to use the physics calculator and how to get a car in to rf2. We had talked about having a discussion about suspension design and you would fit in to that perfectly!
     

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