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Question for the devs concerning ffb differences

Discussion in 'Chit Chat Room' started by Psit, Sep 15, 2015.

  1. Psit

    Psit Alien

    Hey there, since the latest changes into ffb i find that there are huge differences in how ffb is transfered to my wheel.

    Yes, i am using a direct wheel servo drive wheel therefore i get all the small details and some people might not understand what i am talking about.

    For example, in Lotus 49, McLaren F1, Tatuus, RUF Yellowbird, Ferrari F40 and maybe more that i dont remember right now, i get this "road texture" effect coming through the wheel which to me feels awesome. Its like i can count the little rocks inside the asphalt, and it gets stronger as the wheels get more load.

    I can see a pattern here, all those cars are either really old , or pure racers but i should be getting this feeling on McLaren MP4-GT3 (for example) but i dont.

    Can someone from the devs explain this to me? What is it that i am feeling? @Lord Kunos @Aristotelis .

    I use about 50% gain available from my wheel's power, i got damping on 100 in my driver and everything else off.
    I am forcing some damping from the game's .ini (10% i think) to stop oscillations and gyro is at 1.

    Edit: Now that i think of it, it might be that those car's steering is unassisted in real life...

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  3. Winner.
  4. Arch

    Arch Alien

    You're on the money.

    Just vibrations and small creaes turning into movement and, well, vibrations. G27 etc. probably can't feel it at all.

    Power steering usually removes this completely due to the nature of the boost.
    Psit and LeDude83 like this.
  5. JackCY

    JackCY Racer

    I'm not sure AC differentiates between power steering and not. At least I don't see anything like that in car config.
    What does affect the feel in the wheel is suspension geometry and if some of the parameters are low the wheel will be "dead" even on a real car.
    Although with the lack of wheel offset in AC and thus high scrub this shouldn't happen as easily.

    I wouldn't dismiss tyre differences either.

    You should mod a car and see what makes the wheel feel dead.

    There is though this in car config:

    FFMULT=4.0                                    ; Force Feedback power multiplier
    Maybe some Kunos cars have this set so that the FF is dead/low and other high.
  6. Arch

    Arch Alien


    You seem new here. AC does differentiate between no PS and PS racks.


    FFMULT=1.1 ; Force Feedback power multiplayer
    STEER_ASSIST=0.80 ; Variable steer assist, speed relative
    LeDude83 likes this.
  7. Stefano explained the steer assist few days ago and it's not related to power steering (there are cars with and without power steering using same or very similar steer_assist values), neither FFMult, which is simply a way to scale up the forces in cars with particular front geometries (little mechanical trail) so they are higher.

    So no, it doesnt.

    In fact I don't see what is the point of simulating power steering knowing that 95% of the users use cheap toy wheels.
  8. esox71

    esox71 Alien

    See what thought did!:oops:
  9. Lord Kunos

    Lord Kunos His master's voice. Staff Member KS Dev Team

    No powersteering at all, as David is saying the steer assist value has been misinterpreted. The differences are mostly down to suspension geometry with camber, scrub radius.. balance between sprung and unsprung masses and so on. It would be weird if every car felt the same wouldn't it?
  10. Cote Dazur

    Cote Dazur Alien

    about 3 weeks ago I opened this thread in physics moding-Cars and Tyres:


    I did not get any answer, in my case I have not misinterpreted Steer assist value, I just dot not understand what it is, apparently I am not the only one. Lord Kunos can you help us?
  11. Lord Kunos

    Lord Kunos His master's voice. Staff Member KS Dev Team

    ya sorry I don't really have the time to hang over there... I'll try to come around more often.

    Steer assist is a variable power steering. It doesnt work on speed but it works on the amount of force. It's basically a gamma function, I use gamma functions a lot in AC.
    So let's say you have a FF input from -1 to 1 (it's the job of the ffmult to get the actual torque and scale it down to a normalized -1 , 1 range)... the resulting FF after the steer assist will be:


    The job of steer assist is to allow the driver to feel the steer "full" at low speed with cars with heavy downforce without killing his arms if the car is going through a corner at 200kmh. The rule for steer assist is very simple:

    Are you doing a F1/LMS or other VERY high downforce car designed in the last 10/15 years?

    yes ? experiment with steer assist value below 1 only AFTER you've tuned the ffmult to give you a good range of forces in the -1..1 area
    no? steer assist is 1
    Glaurung and Cote Dazur like this.
  12. Arch

    Arch Alien


    Interesting. I wonder what other false knowledge the AC community has circulating...
  13. Lord Kunos

    Lord Kunos His master's voice. Staff Member KS Dev Team

    well in this case it has been misinterpreted internally too.. I guess I was the only one to know what the thing really did :D
  14. F430_458_F12

    F430_458_F12 Alien

    This may be inconclusive as it's an article by someone commenting on the GT field who isn't necessarily a part of it, and it's about GTE, not GT3, but the interview has a driver admitting GTE cars have power steering...so I think the McLaren has it. I can't imagine why it wouldn't.

  15. Psit

    Psit Alien

    Can you let us know which part of the physics make some cars have the road texture feeling and some not?
    Thank you.
    LeDude83 likes this.
  16. Lord Kunos

    Lord Kunos His master's voice. Staff Member KS Dev Team

    I thought I did :-S

    Suspension geometry and every other parameter that makes that car.. there is no


    Kyo, sacredaardvark, Shaddix and 8 others like this.
  17. Cote Dazur

    Cote Dazur Alien

    @Lord Kunos thank you, I had to read the explanation a few times, but I think I get it now. :)
    At the end you write " no? steer assist is 1" does this mean that if I do not want any steer assist effect to alter my FF multi, we should put 1? I thought 0 would cancel any steer assist effect.
  18. Lord Kunos

    Lord Kunos His master's voice. Staff Member KS Dev Team

    it has the same effect, 0 will bypass the calculation, 1 will make it linear which is the same as no calculation.
    LeDude83 and Cote Dazur like this.
  19. Cote Dazur

    Cote Dazur Alien

    Thank you, now I know I got it, makes perfect sense, grazie mile.
  20. Psit

    Psit Alien

    It wasn't so clear to be honest no.
    I do understand its the sum of the physics that make it so different but maybe one day you are going to have one of those aha moments and find a bug in the ffb that creates these differences :D

    Edit: Maybe you have never felt those forces either since you are playing with a G27 so I may not be completely understood.
    Last edited: Sep 16, 2015
    djkostas and F430_458_F12 like this.

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