Lets talk about the MERC GT3 FFB?

Discussion in 'General Discussion' started by LokiD, Nov 30, 2017.

  1. Lazza

    Lazza Registered

    Joined:
    Oct 5, 2010
    Messages:
    9,158
    Likes Received:
    4,235
    @mantasisg Why not just log it, or find previous logs? If you want to focus on physics, remove feel as well. Wheel strength has no effect on what the game is outputting.
     
  2. mantasisg

    mantasisg Registered

    Joined:
    Aug 17, 2016
    Messages:
    2,168
    Likes Received:
    2,995
    I thought about post #25 when I was posting.

    Does wheel strength really has no effect for game output ? I assumed to be so.. But wheel strength is giving the perception.

    I am not quite sure how nominal FFB strength value in .hdv works. Skyppy hdv in moddev explains nominalmaxsteeringtorque parameter as "Maximum steering arm torque to effect force feedback strength". We know that the lower this parameter is, the heavier FFB will be felt, I have not done any investigation to check if it would make difference for actual physics steering torque, I guess it doesn't because it is specifically FFB parameter ?

    I have a question about it. For example: nominalmaxsteeringtorque is set to 7 for some car, does it mean that steering torque of 7Nm will be scaled to full strength of given FFB servo ? What about if FFB servo is capable of higher than 7Nm torque ?
     
  3. doddynco

    doddynco Registered

    Joined:
    Dec 13, 2017
    Messages:
    210
    Likes Received:
    360
    It's a bit of a tricky one to wrap your head around but once you understand it's actually very simple. I will try to explain:

    The car produces a certain feedback value (steering shaft force in nm) depending on physics/geometry - it is not adjustable for the player.

    The nominal figure is determined by the car developer, and only has an effect if the line "Steering torque capability":??, in the player's controller.json is lower than the devs stated value. The nominal is the developers best approximation of the maximum steering force under normal driving situations - so hitting a curb or a big bump isn't counted (it could be thought of as something like 'maximum steering shaft force which can be sustained for 1 second').

    The idea is that if, for example, the Steering torque capability is set to 30nm, and the car steering shaft is experiencing 20nm(nominal) then the game will completely ignore any scaling - the force feedback device with a potential of 30nm will relay the steering shaft force 1:1 allowing the force feedback device to automatically (and realistically) operate with lots of headroom.

    If you are driving the same vehicle with the 20nm nominal force, but are instead using a force feedback device with 10nm, the steering shaft force will be scaled 50%, and will still have some dynamic range.

    To give an audio comparison: The nominal value is like setting the threshold on a limiter - you are effectively choosing where 0dB is.
     
    Last edited: Oct 1, 2020
    mantasisg likes this.
  4. vittorio

    vittorio Registered

    Joined:
    Jan 11, 2012
    Messages:
    1,118
    Likes Received:
    538
    @doddynco thats all very interesting and in theory correct. But the last time few years ago when i looked at maximum steering force for all cars - The ISI Clio Cup was the car with lowest maximum steering force set to 13 Nm. So take a wheel most people use, like Logitech G25/27 .. with Steering torque capability of 2.5 Nm. So FFB would be scaled down to 20%. (or using FFB multiplier of 0.2). That won't work of course and IMO the code was written to work for those low FFB wheels especially.
     
    Last edited: Oct 1, 2020
  5. doddynco

    doddynco Registered

    Joined:
    Dec 13, 2017
    Messages:
    210
    Likes Received:
    360
    Yes but if you have a ffb wheel with 13nm+ (and assuming you've set your Steering torque capability properly) , you will by feeling the correct physics 1:1. So everyone wins.

    The only way this system is limited is that it doesn't account for power steering. So the Mclaren 720s has nominal steering shaft forces of 50-70nm. But in real life, the car has power steering, so the driver is likely getting 10-15nm nominal. The issue is that, even if the dev sets the nominal correctly at approcimately 70nm, a direct drive wheel will relay the forces at full 30nm. So DD owners will have to reduce the multiplier to correct this (probably around 50%)

    That being said, S397 have been very inconsistent with the nominal setting ever since they took over, so ffb user adjustments have been constantly necessary.

    For anyone interested I recommend this simhub display made last year. It has a useful ffb signal meter which also shows the real steering shaft force.
    https://www.racedepartment.com/downloads/dodds-car-info-display.29233/
     
    mantasisg and atomed like this.
  6. vittorio

    vittorio Registered

    Joined:
    Jan 11, 2012
    Messages:
    1,118
    Likes Received:
    538
    Yes, for a FFB wheel with 13Nm+ (steering torque cababillity) and a car with maximum steering force set to 13 Nm it is trivial. Just 1:1 FFB.
    It is not simple and rather difficult when like most wheels have maximum steering force (max. steering torque cababillity) of 2.5 Nm. Your theory says to scale FFB down to 20%. If you do that 80% of rF2 users (using wheels with 2.5Nm max. force) will quit.
     
  7. J7166

    J7166 Registered

    Joined:
    Jun 15, 2019
    Messages:
    161
    Likes Received:
    124
    Does anyone know the reason adjusting caster on GTE and GT3 cars isn't possible in rf2? Afaik it's the only modern sim that doesn't allow this to be changed on these car classes. If that were adjustable it *might* help with the AMG some. Even beyond just the AMG, not sure why these values are locked.
     
  8. doddynco

    doddynco Registered

    Joined:
    Dec 13, 2017
    Messages:
    210
    Likes Received:
    360
    That's not quite right what you've said there. It doesn't scale down the FFB signal in the same way that the ffb multiplier does. Instead, it scales down the steering shaft force so that the nominal is equal to 100% ffb signal; So the 13nm nominal car is scaled down to 2.5nm for the Logitech wheel. This means anything stronger than 2.5nm nominal (basically all vehicles) is scaled to use the full strength of the Logitech.
     
  9. vittorio

    vittorio Registered

    Joined:
    Jan 11, 2012
    Messages:
    1,118
    Likes Received:
    538
    @doddynco ok, if it is that way, then perfect. So every rF2 user should fill steering torque cababillity in controller.json and much better simracing life :) or even should get forced somehow..
     
  10. doddynco

    doddynco Registered

    Joined:
    Dec 13, 2017
    Messages:
    210
    Likes Received:
    360
    Absolutely.
     
  11. Lazza

    Lazza Registered

    Joined:
    Oct 5, 2010
    Messages:
    9,158
    Likes Received:
    4,235
    @mantasisg don't you do physics? How do you not know what the nominal max does? o_O
     
  12. mantasisg

    mantasisg Registered

    Joined:
    Aug 17, 2016
    Messages:
    2,168
    Likes Received:
    2,995
    Thanks @doddynco, I did not know before how exactly game sorts out this issue, and did't know abouts that .json thing before. It makes perfect sense, and typically to rF2 physics is nice to find out how neatly the problem is solved.

    @Lazza Well... You like classic cars just like I do, you could actually give a little go for 1967 Endurance pack cars for example, maybe you'd like them. I did like your physics as I have expressed it in the past. So it means we could possibly have simmilar idea on how the cars/tires are. Maybe. I have mentioned what I know about nominal max steering torque value and it has been enough so far to adjust FFB, however I don't have several rigs at my disposal. I have T300, but I can not check how they would feel on 2Nm G29 and >20Nm DD wheel, but it turns out to work in some way close to what I was expecting as doddynco has explained.
     
  13. SuperMonaco_GP

    SuperMonaco_GP Registered

    Joined:
    Jun 11, 2020
    Messages:
    39
    Likes Received:
    39
    I have a Simucube2 Sport. I can assure you it's not a matter of higher or lower end wheels. the ffb and/or the physics of that car is completely broken, and it can be felt very clearly even with 17Nm of direct drive power in your hands.
    Also, the same car appears in almost every other sim, AC, ACC, iracing, R3E but the rF2 is the only one that drives like so. I think it's a lot more plausible that S397 got it wrong instead of saying "all other sims got it wrong and just we got it right", don't you think?
     
    Last edited: Oct 1, 2020
  14. mantasisg

    mantasisg Registered

    Joined:
    Aug 17, 2016
    Messages:
    2,168
    Likes Received:
    2,995
    Judging by post #25 telemetry data and our discussion in recent posts about nominal steering torque parameter functionality in rF2 it should be possible for you to experience Merc FFB in 1:1 scale. In post #25 telemetry it shows that Merc peaks at about 15Nm, and drops to around 4-5Nm when in turns (must be understeering then). 4-5Nm is not so little. I have no idea about other sims, but I'd suspect other sims might have kind of more strict quality standards, and higher compliance to consumers which may discard any decisions that could ever possibly be perceived as a little bit peculiar and even assumed as "completely broken". Which could be either right or wrong, I suppose.
     
  15. Bidle

    Bidle Registered

    Joined:
    Jul 13, 2019
    Messages:
    82
    Likes Received:
    51

    I just did a few laps with the Merc GT3 and it is indeed not good and completely off.
     
  16. thoyun

    thoyun Registered

    Joined:
    May 31, 2014
    Messages:
    3
    Likes Received:
    1
    Merc vs Ferrari

    Simucube1 20NM, Overall strength 100%
    In RF2, FFB multiplier 0.2

    FFB output & Steering shaft Torque(Below)
    Turn 5, Silverstone
    Color : Merc
    White : Ferrari Turn 5.jpg

    Turn 8 & 9 , Silverstone Turn 8,9.jpg
     
    Last edited: Oct 1, 2020
    Lazza likes this.
  17. doddynco

    doddynco Registered

    Joined:
    Dec 13, 2017
    Messages:
    210
    Likes Received:
    360
    I find the Merc to be excellent. It has really nice steering geometry - it takes some time to learn its character.

    I don't want to be that guy, but you guys complaining - I think you're making one of two driving errors (or both). Either - you're not trail braking properly and/or you're steering in too much/too harshly on entry. Basically you're asking too much from the front tyres without first transferring weight onto them. The steering geometry of the Merc is just highlighting this error - which is probably intended as in real life your tyres might last only 15 laps on a good day if you drive like that.

    With a ffb wheel capable of 4nm like the T300, it's going to be very easy to push the car past the optimum slip angle, and so the weaker the ffb wheel, the more likely you are too turn into that 'light' understeering state. The Merc is just good at showing you what you're doing wrong.

    If you're rushing past 90degrees of steering lock on entry, you're doing it wrong. If you are dropping off the brakes completely and then expecting the cars front end to stick, you're doing it wrong.

    I promise you that, if you just be more gentle with the steering on entry, whilst concerntrating on trail braking and allowing the tyres to progressively get up to tempreture, the awesome handling will reveal itself to you.

    Every complain about this car seems to come from someone who has read some criticism, jumped in and thrashed it on cold tyes and said 'yeh it's definetly broken it understeers'

    Just calm down and drive it like you're paying for the tyres.

    These two tests are done with a OSW30nm with 75% muiltiplier.


     
    mantasisg likes this.
  18. doddynco

    doddynco Registered

    Joined:
    Dec 13, 2017
    Messages:
    210
    Likes Received:
    360
    'Two different cars handle differently'

    It doesn't really tell us anything other than it's not driving as you expect it to.

    Why have the multiplier so low? At 0.2multi, it's going to very easy to push past the peak slip angle with a osw20nm.
     
  19. DrivingFast

    DrivingFast Registered

    Joined:
    Mar 1, 2018
    Messages:
    1,639
    Likes Received:
    1,080
    A lot of good things in this post.
     
    mantasisg likes this.
  20. thoyun

    thoyun Registered

    Joined:
    May 31, 2014
    Messages:
    3
    Likes Received:
    1
    Intended steering geometry! It's very interesting. I want to learn more.

    I think that Merc's FFB is not broken, but
    'The FFB rate of lightening' is excessive even at optimum slip angle.
     
    Last edited: Oct 1, 2020

Share This Page