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Automobilista - How the FFB works and what is new about it

Discussion in 'Automobilista - General Discussion' started by Renato Simioni, Mar 9, 2016.

  1. Renato Simioni

    Renato Simioni Administrator Staff Member

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    This is an amended copy of a post @Niels Heusinkveld made in Reiza 51, which is relevant to all AMS users. Follows:


    What's new in AMS?
    So we did a few things that affect the FFB positively (we'll get into possible negatives later :))
    - Physics run at 720hz instead of 360, tire / road contacts are more precise and 'more often'
    - FFB is no longer limited by framerate or a maximum of 90hz, we fix the value at 720, 360, 240, adjustable in the controller.ini
    - We read the wheel position at 500hz instead of ~110hz, so tiny fast changes in wheel position (also the result of the FFB 'turning your wheel!) get put back into the physics engine more often

    How does the FFB get calculated?
    There are 2 parts to the FFB. The main steering forces come from the RealFeel plugin. On top of that there are Off, Low, Medium, High and Full settings. So in short this comes to:

    Part1: 'fake' effects
    - LOW
    (now PURE 360 hz): Realfeel forces only
    - PURE 180 hz: Realfeel forces only, but at half the rate
    - MEDIUM (now PURE + EFFECTS 1): + damping, friction, kerb 'pull', kerb 'shake', jolts from impacts at 180 hz
    - HIGH (now PURE + EFFECTS 2): +brake pedal steering vibration, at 180hz
    - FULL (now PURE + EFFECTS 3): + engine RPM vibration, car speed vibration, at 180hz.

    The controller.ini parameters do *everything* with these extra settings. You can run PURE + EFFECTS 3 ffb but have all the effects set to do nothing in the INI, and you won't feel them!
    These effects can be updated up to 720hz depending on your controller.ini setting.

    Part 2: RealFeel effects
    We still use the RealFeel plugin, only now it is not limited to the framerate and we increased the plugin rate to 360hz. This is the.. name says it .. *real*, or "PURE" part of the force feedback: tire contact patch forces push or pull the suspension steering arm and this force is sent to your wheel.

    Each car has its own entry in the RealFeelPlugin.ini file where the 'clipping force' is set (MaxForceAtSteeringRack) - that is the peak steering force for that car (negative or positive relating to the suspension layout). You can edit these values to se it lower then the absolute peak force (ex -4000 when the actual peak steering rack force on a given car is -5000, or 1500 when the actual peak is 2500), your FFB strength will be scaled accordingly & forces beyond that value will be "clipped".

    All our default realfeel values are set with 20-30% of clipping, as otherwise FFB can be quite light under lower loads with the average steering wheel. If you have a stronger wheel, you may want to reduce or eliminate the clipping for each car by increasing its respective MaxForceAtSteeringRack.

    There is also a setting "SmoothingLevel" which, now that we get a lot more samples, can be enabled without causing a lot of lag. Previously, at 90hz FFB, 10 frames of smoothing would be 0.1 second. Now at say 360hz, 10 frames of smoothing would only take 0.03 seconds. By default we use 2-4 depending on the car.

    What does REIZA have to do to AMS FFB:
    1) Fix a few remaining issues:
    - When pressing Replay, FFB should not be active
    - When paused, the FFB should not be active



    What should be so new and different and better about this new FFB stuff then?
    When working as it should, increased physics rate means the sim calculates the forces on the tires more often. Going over a kerbstone at 200km/h it will 'see' more of the kerbstone ups and downs and transmit them to the force feedback. The increased rate force feedback also reports these updates to your wheel. You should feel the 'road texture' (a constant slight noise on most tracks) very subtly and taking a kerb at 50km/h will feel more clearly different from taking it at 250km/h. Previously the limited rate would have meant above, say, 125km/h the kerb wouldn't feel any 'different' anymore.

    How to get he most 'pure' FFB feel:
    - Set FFB effects to '
    PURE 360 hz'
    - If you have a strong wheel, enable some 'always on' damping on the wheel software, you certainly need it, but how much is subjective
    - Please note that such stronger wheels may cause performance issues when running at PURE 360hz - if you have a high end wheel and experience very poor FPS, try setting FFB to "Pure 180hz". It should resolve the issues and any FFB fidelity loss should be negligible.


    EDIT: As per release notes from v0.9.8:



    The main change is the pneumatic trail fix via PneumaticTrailGripFractPower (PTGFP) function, which is embedded in the physics. It´s changed how pneumatic trail works and its effect on the FFB, which should provide a much more natural feeling for tire grip.

    We have also added a "FFB Low Force Boost" Slider to the Controller menu - this works sort of like a "Minimum Force" setting, in which higher settings (around the default 80%, recommended for Logitech wheels or similar) the forces come in earlier, while lower settings (20-40% which are the old defaults) are recommended for stronger FFB wheels such as T500, Fanatec CSR V2. If you have a Bodnar or an Accuforce-type wheel, you probably don´t need this setting at all and may keep it at 0%. The graph below gives an idea of how slider works:
    FFB_sensitivity.jpg

    Adding this force boost slider allows us to set default values in Reafeel with more accurate values (less clipping) than before, since weak FFB on lower range wheels is less of an issue. PTGFP in turn makes FrontGripEffect in Realfeel unnecessary so that´s now set to 0.0 globally (vs 0.2 before).

    Finally FFB while the car is standing or moving very slowly has received some new code of its own (unrelated to the FFB while driving, though its effects can also be increased/decreased by the FFB Boost). We have added some lowe speed functions and tweaked the "parking lot" realfeel values to eliminate or at least minimise wheel vibrations / oscillations while standing still.

    All of these should hopefully grant Automobilista an all around stronger, more realistic FFB.
     
    Last edited: Aug 29, 2016
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  2. Ricardo

    Ricardo New Member

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    This is a good post, I think it would be great to have translated the discussion area in Portuguese
     
  3. Gevatter

    Gevatter Active Member Reiza Backer

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    Thanl you for this post, it helped me a lot. In GSC I actually always user "Full" FFB settings, because I thought that gives me the 'full' experience. Well, it kind of did, but it was nur the purest :)

    I already posed this question in the Force Feedback (FFB) thread (Logitech, Thrustmaster, Fanatec, OSW, etc.), but my experience is that while the low downforce cars feel amazingly good, the high downforce cars /Formula 1 mainly) clip a lot in fast corners, but if I reduce FFB either in general or the MaxForceAtSteeringRack parameter in the realfeel.ini, those same cars lose almost all detail in the slower corners.

    Is there a way to cap the forces before they clip or modify the FFB linearity so its stronger at the low end but evens out at the top?
     
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  4. Msportdan

    Msportdan Well-Known Member Reiza Backer

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    i do get the hard ffb in the f1 cars like you.. You may have to edit real feel ini. Im not entirely sure what to edit vo. ?! :(
     
  5. Gevatter

    Gevatter Active Member Reiza Backer

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    In the thread I linked on the second page there is a link to a post from Niels at Race Department detailing the entries in the realfeel.ini. So, MaxForceAtSteeringRack is the FFB strength. By editing this, you essentially make the FFB weaker or stronger for the given car, but just linear. Like I described, if you tweak it to avoid clipping, it becomes very weak at low an mid-level speeds.
     
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  6. Msportdan

    Msportdan Well-Known Member Reiza Backer

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    agreed.
     
  7. Marc Collins

    Marc Collins Well-Known Member Reiza Backer

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    I have a technical question about the FFB and RealFeel.

    DefaultFrontGripEffect=0.200000

    This line is in the RealFeelPlugin.ini file and 0.2 appears to be the default/overall setting. Is there a layperson's explanation of what exactly this variable does? Changing it has a profound effect on the FFB feel (not surprising!), but I suspect that it impacts different hardware in different ways. So to start, thanks for having an adjustment in the first place.

    In my particular case, my hardware and/or some combination of my brain prefers lower values. I tried several cars at 1.0, 0.8, 0.2 and 0.0 to confirm. I always prefer 0.2 or less...often feeling that 0.0 is just great. I can imagine that 0.0 causes some issues of harshness on some systems, so not suggesting a change from the 0.2 default. But an explanation of what this is doing "under the hood" would be much appreciated and should be helpful for others who either want to experiment or because of their equipment may need to adjust to get the best experience out of the sim. Thanks!
     
  8. Gevatter

    Gevatter Active Member Reiza Backer

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    I have a question regarding the Skip FFB Updates setting.

    Have I understood that correctly, that the Skip Updates = 0 setting in the controller.ini only affects the canned effects and RealFeel always works at a maximum of 360Hz? So, by that logic, if I use the setting "Pure 360Hz", it should make no difference for me wether i set Skip Updates to 0 or 1?
     
  9. Spin

    Spin Active Member

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    1,a) What's Overall FFB Actually Doing?
    What exactly does the in-game FFB overall strength slider do? If I'm not mistaken, it doesn't control, nor is it "connected", to RealFeel, so what really is it adjusting?

    1,b)
    How does it tie-in with RealFeel's "MaxForceAtSteeringRack"?

    2,a) "Friction Coefficient": Negative and Half of "Damper Coefficient"?
    Many guides and websites state that the controller.ini's "Friction Coefficient" should be A. set to a negative value ("Damper Coefficient" stays positive), and B. set to around 50% of the value of "Damper Coefficient". Is this true?

    2,b)
    Would this make no difference, at all, if using FFB mode "Pure"/"Low"?

    3) "Force Exponent": Overall FFB Strength Output Linearity?
    "FFB Steer Force Exponent" in the controller.ini sounds like it's the overall FFB output linearity (like rFactor 2's "Steering Torque Sensitivity" AKA "STS"). Is this true and does this setting still apply when using RealFeel and FFB mode "Pure"/"Low"?

    4) "Force Output Max": 0.0 to Truly Use "Pure" FFB?
    I've read from at-least two people that to truly disable all original FFB (except rumble-strip effects just in-case you race on a track which uses fake rumble strips), and therefore only use RealFeel FFB, that the controller.ini's "Steer Force Output Max" must be set to 0. Is this true?

    5) "Force Input Max": Magical Value for Increased FFB Fidelity?
    I remember reading a ton about changing the controller.ini's "Force Input Max" from 11500 to 65535. I think there's a setting in the RealFeel.ini containing the same value which you're then supposed to change and match (65535 instead of 11500). The 65535 value apparently offers greater fidelity/depth to the FFB or something. Is this true?
     
  10. Niels Heusinkveld

    Niels Heusinkveld Moderator Staff Member

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    Answers to my knowledge, but when in doubt, test some extremes to see if it indeed doesn't matter (or does)

    1) The in game FFB strenght slider changes ALL FFB, including realfeel. Literally everything, so if you use damper in the controller.ini, or kerb pull factor or any effect, or realfeel, all get multiplied by the in game FFB strength %.

    2) I've never used friction. Pure (what was LOW before) doesn't use damping, probably doesn't use friction either. Friction by definition goes against something, so I would be very surprised if the value would make any sense if you set it negatively!

    3) Force Exponent shouldn't affect realfeel. I doubt it affects the 'fake effects' much and I would assume it only affects the 'rFactor original' steering force FFB. I'm not 100% sure on this at the moment, why not try 'pure' FFB and some super extremes of the exponent?

    4) Force output max should not play a role, if the realfeelplugin.ini file has the 'FFBmixerrealfeelpercent' at 100, but I may not have double checked this..

    5) Force Input Max is a nice myth from the past. First it shows how people overrate the ability of their FFB wheels, thinking that 23000 steps of FFB strength isn't enough.. And it would only be true if the FFB was calculated as an integer.

    I've had some strange things happen with FFB reversing at some point, but in general, this value is fine even at 1, showing that, realfeel at least, doesn't use integers but probably uses floats or doubles, giving us 'many digits' after the comma and 'about a million or more' steps of force.
     
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  11. GrimDad

    GrimDad Member Reiza Backer

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    Welcome to the forum Niels ;) been a fan of your work for awhile.
    Hope to own a set of your pedals one day too.
     
  12. Niels Heusinkveld

    Niels Heusinkveld Moderator Staff Member

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    The physics have a 'value' for the tires as an indication of how much these are gripping. At 1 they are totally gripping at 0 they are totally sliding.

    FrontGripEffect at 1.0 multiplies the steering forces by this. So the more the front tires are sliding, the smaller their 'grip factor', the more FFB will be reduced. Values in between 0 and 1 change how much of this is felt, so at 0.1 you only feel a little bit of extra drop in FFB, but at 0.9 you feel a lot of drop off as the tires slide more.

    Image attached!

    It is not quite ideal, we are looking at ways to do this better. RealFeel can't just lower the tire part of the FFB, it only knows the 'steering rack force'. The force on the rack includes more than just tire skidding. So a higher value lowers ALL 'physics FFB', including things like caster which you feel in a go kart as it jacks up the car for example.

    Subjectively we quite like a value of 0.2 as it gives some indication of 'understeer' without numbing the forces too much.
     

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  13. Niels Heusinkveld

    Niels Heusinkveld Moderator Staff Member

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    Skip = 0, RealFeel 360hz, canned effects 720hz
    Skip = 1, Realfeel 360hz, canned effects 360hz
    Skip = 2, Realfeel 240hz, canned effects 240hz
    Skip = 3, Realfeel 180hz, canned effects 180hz.
     
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  14. Spin

    Spin Active Member

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    Thank you, thank you, thank you, thank you, and thank you!
     
  15. Spin

    Spin Active Member

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    I heard that, while RealFeel is the best for "pure steering rack FFB", Leos FFB is the best for feeling tyre grip. I guess it's like a better version of the default controller.ini FFB with regards to the grip FFB settings?? Do you personally think there's any room for a RealFeel + Leo's FFB combination to be built natively into AM that way we can have tyre/grip based FFB (for those of us who like it) combined with RealFeel which would allow use to continue running Pure/Low FFB but with more tyre grip cues because of Leo's "marriage" with RealFeel?

    I feel that getting a sense for pure tyre grip and slip and amounts of slip/grip (not steering forces, bumps, etc. which seem quite good) could use quite a bit of improving - regardless of car (overall game/engine thing) - but I guess it's just down to the ISI pMotor tyre model rather than a FFB "thing" since RealFeel is only using the steering rack forces.
     
  16. Marc Collins

    Marc Collins Well-Known Member Reiza Backer

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    Thanks for the explanation. It doesn't match why or how it seems I can feel exactly what the car is doing better when I set this to 0.0 instead of 0.2. And the higher values are extremely unsatisfying for me and my wheel...but I suspect someone out there might like them.

    My perception as someone who drives real race cars occasionally and drives a high performance car (with manually adjustable racing dampers) as an everyday vehicle is that I can feel all four corners of the car in balance at 0. Anything above 0 and the bias starts moving toward the front of the car. At 1.0, I can only feel the front of the car. This does not sound like it aligns with what is really supposed to be happening...but it doesn't matter as we can adjust this if we need to. 0.2 is OK by the way. I had no major concerns about it as a default and would be acceptable to use if there was no adjustment.

    But please, as you work towards a new system, please always leave major variables like this adjustable at least in the config files. I am convinced that with so many different types of hardware out there and the varying ways we humans perceive things, that a one-size-fits-all approach for a racing sim would be a disaster. So keep doing what you are already doing :)

    I look forward to trying anything new in the beta process.
     
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  17. Transyt

    Transyt New Member

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    Hi, I have a question for the FFB dead zone problem. For wheels like G27, when you place your wheel in the center, and begin to rotate it, there is no torque output within certain degree. The output torque kicks in when you turn more. That makes your wheel a toy and kills immersion, especially when you drive straightforward. Lately on RD, there's an APP for Assetto Corsa called LUT generator. It checks your wheel torque output curve, and compensates the none linear torque output, to makes it linear from the center of your wheel. Assetto Corsa drives much better with this APP. So I wonder, if there is similar way (or any otherway) to make AMS kill FFB dead zone in the wheel center area? I really looking forward to seeing this problem solved.
     
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  18. SaxOhare

    SaxOhare Active Member Reiza Backer

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    @Transyt Perhaps this is helping you

    From the Steam discussions

    I have noticed some people complaining of a massive hole in the FFB with G27 wheel.
    The way I fixed it is to download a small app called wheelcheck.exe and check your wheel's "Min Force" setting, mine is 14.5% by the way.
    Then edit your controller.ini and change the FFB steer force neutral function from "0.00000" to "0.14500" (in my case) which is 14.5% as a decimal. If your wheel Min Force is 8.5% then change it to "0.08500" for example. Then save the file and the hole in your FFB should have gone. I actually set mine at 0.13500 to give a small amount of leeway to prevent overcompensating.

    You can also improve the feel of FFB further by removing the default FFB deadzone which is meant to prevent wheel oscillation. Edit this line in controller.ini FFB steer force neutral range="0.04500" and change it to "0.00000". You might have to increase this slightly if you get wheel oscillation but mine works fine set at zero.

    If anybody wants more detail about this let me know. This works for me but obviously there are differences in PCs and wheels which means it might not work for you, but give it a try and let me know if it improves FFB for you.

    Cheers
    GLYGOO
     
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  19. Transyt

    Transyt New Member

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    Hi, thanks! I tried, it helps a little. But it improves much in packing lot situation. When it drives, the dead zone is back. I also noticed that formula cars have the narrow dead zone comparing to road cars, and high speed situation has narrow dead zone comparing to low speed. Maybe I should check into real feel plugin. It looks like you can not completely eliminate dead zone. Any chance of official support for LUT calibration?
     
  20. Marcel Kleene

    Marcel Kleene Member Reiza Backer

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    I'm still not happy with my Accuforce Settings. I don't feel the car as I could with GSCE. In high speeds it's ok...but in speeds below let's say 150km/h the FFB gets very loose. On low speeds, I don't feel the car like I did in GSCE. For example on the start, I could control the slide very well..could regulate the throttle so good, since I felt everything in the wheel. Now, no chance anymore...

    Is there a way that I can get the exact same feeling as in GSCE? Can I use the figures from realfeel.ini from GSCE?

    I run the wheel on 360 pure. Skip updates at 3.

    Niels, did you ever do a realfeel.ini or controller.ini for DD wheels?
     
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