Physics and tire models of racing sims

Discussion in 'General Discussion' started by Korva7, Apr 4, 2015.

  1. Korva7

    Korva7 Registered

    Joined:
    May 22, 2014
    Messages:
    700
    Likes Received:
    206
    There is lot of talk about assetto corsa's ffb to be fake/canned but is there any evidence about that?

    Andregee says there that kunos have said it to be "generated by the suspension geometry" and i can't say that it couldn't be so. There is separate slider for "slip effect" in AC, and i have put it to 0 beacause i think it might be kind of canned effect that tries to simulate vibration of the car you feel through your seat under slide. But otherwise it feels pretty okay to me.

    There is differences to rF2 and one is refreshrate of ffb. I remember i heard that rF2's was 400hz and AC's 60hz. Can't be sure about those numers, but could that cause AC to feel more artificial and cause people to be more suspicioius about it's "realness"?
     
  2. Adrianstealth

    Adrianstealth Registered

    Joined:
    May 28, 2012
    Messages:
    4,578
    Likes Received:
    1,071
    AC's ffb has always felt terrible to me , but then some others think it's brill -tires feel basic but maybe as a result of the ffb -canned effects are obvious (press the brake whilst car stationary is an example) & those slider "effects" are laughable

    iracing ffb is solid now -improved a hell of a lot over last 3 to 4 builds (new build every 3 months approx ) they seem to stick to keeping it simple & well defined low "noise" in the forces, tires have improved also & communicate a lot more logically now

    rf2 ffb has always been super, there's alot going on & it works very well maxing out user sensation & surpasses a point of quailty of what I'd ever thought to be possible, tires are nice too although I've felt they should seem a tad "sharper" -a bit more difined in how they communicate to the user, flat spotting etc are advanced features that are great to have too ( ps not used rf2 over last 2 or 3 builds so my info here may be a tad out of date )
     
  3. P.S.R.

    P.S.R. Registered

    Joined:
    Jun 15, 2014
    Messages:
    1,794
    Likes Received:
    4
    Dude big changes recently I think starting with 930 or prior build. Just FYI.
     
  4. Adrianstealth

    Adrianstealth Registered

    Joined:
    May 28, 2012
    Messages:
    4,578
    Likes Received:
    1,071
    thanks PSR, I look forward to trying rf2 again, sims are getting mind blowingly good hey, we are very very lucky !
     
  5. Korva7

    Korva7 Registered

    Joined:
    May 22, 2014
    Messages:
    700
    Likes Received:
    206

    Here is someone driving the same car and track in gsce as he has driven in real life.
    5.20->
     
    Last edited by a moderator: Apr 6, 2015
  6. hexagramme

    hexagramme Registered

    Joined:
    May 25, 2013
    Messages:
    4,245
    Likes Received:
    194
    I will say that I really hope the problem lies in the ffb (canned to a certain degree).
    If it doesn't then it means that the underlying physics are even more flawed than I thought...
     
  7. Acoutsa

    Acoutsa Registered

    Joined:
    Jul 17, 2014
    Messages:
    34
    Likes Received:
    0
    It is clear that most of us find that AC gives us a force feedback steering wheel that is not necessarily based on reality and car physics is not really believable !! I find AC realistic enough on its force feedback on the steering wheel and on the physics of cars !! Yesterday I start to play Rf2 is I realized that it is far more fluid driving FFB level and at the level of drift that is very difficult to faires !! Also the graphics level Rf2 is much better !!
     
  8. Korva7

    Korva7 Registered

    Joined:
    May 22, 2014
    Messages:
    700
    Likes Received:
    206


    Interesting stuff. I did jump over plane things, and haven't watched it to the end yet.

    One thing they speak about is that Pacejka formulas don't work at slow speeds, so sims that use Pacejka formulas have to use different formulas in slow speeds, and driving at the speed where formulas are changing might feel wierd or difficult.
     
  9. Jokeri

    Jokeri Registered

    Joined:
    May 17, 2014
    Messages:
    204
    Likes Received:
    32
    In AC steam forlder system/cfg/assetto_corsa.ini there is text:

    [FORCE_FEEDBACK]
    MAX_FF_RATE_HZ=333

    I assume that it the refresh rate .
     
  10. Korva7

    Korva7 Registered

    Joined:
    May 22, 2014
    Messages:
    700
    Likes Received:
    206
    Okay. It probably is not causing much difference then. Thanks.

    I'm almost at the end of the video i sent. They speak about sticks and stones simulation. You may have to watch the video to understand, but i have a image that rFactor2 tire model is more about sticks and stones than Pacejka, or some other, formulas. Atleast, the idea of trying to model tyre's construction, makes me think like that.
     
    Last edited by a moderator: Apr 6, 2015
  11. msportdan

    msportdan Banned

    Joined:
    Apr 22, 2014
    Messages:
    850
    Likes Received:
    0
    So does rf2 use pazejka and does gsc\rf1?
     
  12. Korva7

    Korva7 Registered

    Joined:
    May 22, 2014
    Messages:
    700
    Likes Received:
    206
  13. Adrianstealth

    Adrianstealth Registered

    Joined:
    May 28, 2012
    Messages:
    4,578
    Likes Received:
    1,071
    just watched the whole thing, good vid,

    thanks for posting
     
  14. Emery

    Emery Registered

    Joined:
    Oct 24, 2010
    Messages:
    3,035
    Likes Received:
    1,654
    rF2 uses a model for the player and Pacejka for the AI that's calculated off the model. rF1 and all games based on that engine (GSCE, R3E, GTL/GTR/GTR2/Race07/RaceOn, & probably a few others that I can't think of) use Pacejka for both player and AI.

    For rF1, the Pacejka curve (really a largish table with interpolation) is used with a pneumatic trail modifier and grip multiplier and tire inflation and tire temperature. Pacejka curve is the overall feel of the tire while you're cornering, whether it's sliding or gripping. Pneumatic trail is what you feel at turn-in, it's the delay caused by the tire distortion taking a set as a result of the forces. The grip multiplier produces the skidpad figure, so to speak. I think everybody has a feel for how inflation and temperature should affect grip. The AI use a simplified form and have an AI grip multiplier on top of the player's grip multiplier.
     
    Last edited by a moderator: Apr 6, 2015
  15. Jokeri

    Jokeri Registered

    Joined:
    May 17, 2014
    Messages:
    204
    Likes Received:
    32
    Excellent video korva7!!!
     
  16. msportdan

    msportdan Banned

    Joined:
    Apr 22, 2014
    Messages:
    850
    Likes Received:
    0
    whats the overall opinion of pacejka vs rf2 new physical model then..?

    is it a better model now or is the tried and tested pacejka model better?
     
  17. Rich Goodwin

    Rich Goodwin Registered

    Joined:
    May 3, 2012
    Messages:
    1,219
    Likes Received:
    9
    What's your opinion?
     
  18. msportdan

    msportdan Banned

    Joined:
    Apr 22, 2014
    Messages:
    850
    Likes Received:
    0
    good question.. :)

    my honest opinion, is that the new physical model simulates tyre heat and wear much better, it seems to be more dynamic on parts of the tyre that actually are affected.

    Handling wise, I struggle to differenciate them. I know RF2 model is chucking more numbers into the mix, and I said above I can notice that, but If I took that away (tyre temp/wear), not sure Ill notice a difference. The ffb feels more reactive to what surface/gradualtions the tyre is currently travelling over, and directly affecs ffb rather than be a effect that just happens.

    but that's my novice opinion.From someone who has never played rf1, only GSC and a few years on RF2. also played AC and RRE, who imo do not compare to the GSC/RF2
     
  19. Associat0r

    Associat0r Registered

    Joined:
    Oct 5, 2010
    Messages:
    307
    Likes Received:
    10
    You can solve that by avoiding the use of slip angle and slip ratio directly as input in your equations. http://www.performancesimulations.c...comments-relating-to-low-speed-tire-behavior/
     
  20. buddhatree

    buddhatree Registered

    Joined:
    Dec 22, 2011
    Messages:
    1,700
    Likes Received:
    249

Share This Page