Tyre friction/interaction with road surface

Discussion in 'General Discussion' started by green serpent, Nov 9, 2016.

  1. green serpent

    green serpent Registered

    Joined:
    Feb 2, 2016
    Messages:
    625
    Likes Received:
    604
    I haven't looked at any telemetry, but today I've spent a bit of time looking at the pedal overlay while doing various tests (albeit not very scientifically). Going through the same corner at different speeds (eg 60km/h, 100km/h, 120km/h), the overlay is showing what would be expected (higher ffb with higher speeds). Exceeding front grip levels (even with higher caster settings) sees a small drop in ffb followed by quick up/down fluctuations.

    As previously suggested the problem that I'm having is down to hardware issues rather than any problems with the ffb. For example at approx 50% force vs 90% force (according to the pedal overlay) I don't feel much difference in torque.

    I can't seem to find that skid pad mod anywhere, but if anyone has a link to it I wouldn't mind doing some better tests in a more controlled environment (ie smooth surface).
     
  2. Emery

    Emery Registered

    Joined:
    Oct 24, 2010
    Messages:
    2,864
    Likes Received:
    1,475
  3. green serpent

    green serpent Registered

    Joined:
    Feb 2, 2016
    Messages:
    625
    Likes Received:
    604
    Many thanks.
     
  4. Euskotracks

    Euskotracks Registered

    Joined:
    Nov 29, 2013
    Messages:
    1,093
    Likes Received:
    191
    If at 50% pedal overlay you feel the same as with 90% then your wheel is not OK. it would seem taht you are actually clipping your wheel
    If you increase FFB multiplier do you get a higher FFB?
    In case your wheel is clipping, you should reduce FFB multiplier. Reduce steering torque sensitivity below one if you also want to increase ffb drop. You will probably not feel lower end forces.
     
  5. Euskotracks

    Euskotracks Registered

    Joined:
    Nov 29, 2013
    Messages:
    1,093
    Likes Received:
    191
    STS is a FFB postprocessing function that amplifies the FFB variation for higher forces as it can be seen in the graph where you configure it. There is no need to check anything in telemetry.
    should we check that FFB multiplier increases FFB intensity?
     
  6. Lazza

    Lazza Registered

    Joined:
    Oct 5, 2010
    Messages:
    10,788
    Likes Received:
    5,558
    Keeping what's said in context, and not just the words themselves you've quoted, of course that's what STS does. Moving it away from 1 will make the force more dynamic at one end and less dynamic at the other; above 1 will make it more dynamic at the low end, and below 1 will make it more dynamic at the high end.

    Making the assumption that peak cornering force is somewhere in the upper end of the possible FFB range (and if we're talking about a relatively weak wheel, it wouldn't make much sense to have it otherwise), you would exaggerate the force dropoff by having STS below 1, making the higher-forces FFB curve steeper.

    Of course, as Euskotracks points out, you need to ensure you aren't somehow 'breaking' the FFB output by clipping etc.
     
  7. Euskotracks

    Euskotracks Registered

    Joined:
    Nov 29, 2013
    Messages:
    1,093
    Likes Received:
    191
    Steering torque (Nm) is directly calculated by the physics and remains constant regardless the ffb settings you use.
    FFB output is later calculated based on the different settings you use. How is this output calculated?
    It is very simple. The controller has an steering torque equivalence for 100% FFB.
    Raw steering torque (the one in telemetry) is afterwards modified by FFB multipler, STS, STM... Finally, the obtained value is converted to FFB% considering the initially set equivalence. Of course the resulting value cannot exceed 100℅. For my G27 and Formula ISI, 20Nm ST = 100% FFB

    If you use lazza's DAM plugin where both ST and FFB are logged you will easiky understand what's going on. I will probably upload some images later in order to be more clear.
     
  8. green serpent

    green serpent Registered

    Joined:
    Feb 2, 2016
    Messages:
    625
    Likes Received:
    604
    I couldn't agree with this more, however I find that the only way I can get an aligning force that feels realistic, is by lowering the FFB multi. I am always surprised at how great the ffb feels when I drop it down to around the 0.80 mark (depending on mod/setup). If I run a higher ffb multi, then aligning forces feel too strong, and "shoot the tires off in the opposite direction that you turn". But the downside of running the lower ffb multi, is that I miss out on the really strong forces. It is hard to articulate, but ideally I would want a heavy feeling ffb, without the rubber band type aligning torque that I experience with a higher ffb multi.

    I need to play around with the STS some more, but essential that is what I'm after, a weaker aligning torque at moderate steering angles, but then a heavier weighted feeling at higher turning angles. At the risk of repeating myself several times (sorry), currently it's either light everywhere (feels fantastic and realistic, however missing that 'bite' feeling during harder cornering), or heavy everywhere (hard cornering feels good, but too much aligning torque at small steering angles and 'easy' corners).
     
  9. green serpent

    green serpent Registered

    Joined:
    Feb 2, 2016
    Messages:
    625
    Likes Received:
    604
    I've set STS to some extreme values eg -10.0 and I still can't really perceive a difference. I'm assuming that going into negative values doesn't do anything. What scale does it work on? Is it simply 0 through to 2?
     
  10. Lazza

    Lazza Registered

    Joined:
    Oct 5, 2010
    Messages:
    10,788
    Likes Received:
    5,558
    I think if you play with the axis sensitivity slider in the controls menu you will see a fairly good approximation of what the 0-2 range does to output when setting STS.
     
  11. Euskotracks

    Euskotracks Registered

    Joined:
    Nov 29, 2013
    Messages:
    1,093
    Likes Received:
    191
    I am not sure if a value lower than 0 is admitted but it is easy to check since the effect ia easily represented with motec i2 and DAM plugin. Regular motec plugin doesn't log FFB% output.
     
  12. Lazza

    Lazza Registered

    Joined:
    Oct 5, 2010
    Messages:
    10,788
    Likes Received:
    5,558
    Think of it this way: let's say in two particular situations you have 50% FFB output and 90% FFB output.

    If you increase STS, the initial slope of the response curve will be steeper (as above, try >100% sensitivity in the controls menu to visualise this), and those same scenarios might end up with 65% and 95% output.

    Conversely, lowering STS might result in outputs of 35% and 85%, because the curve is flatter at low forces and steeper at high.

    The difference between the two scenarios ends up changing from 40%, to 30% (higher STS), or 50% (lower STS). Note that two forces in the lower half of the curve would alter in the exact opposite way, so where the forces you're talking about actually are is important.

    Note: no maths was involved in arriving at these figures...
     
  13. Euskotracks

    Euskotracks Registered

    Joined:
    Nov 29, 2013
    Messages:
    1,093
    Likes Received:
    191
    Have you checked in the telemetry whether FFB% drops as steering torque does when you understeer? It might be working as it should but maybe you are expecting something else.

    As already said several times, FFB is an output of the simulation
     
  14. Lazza

    Lazza Registered

    Joined:
    Oct 5, 2010
    Messages:
    10,788
    Likes Received:
    5,558
    Ok, let's go back a step.

    STS affects how 0-100% FFB is output to your wheel. So I'm saying you're wrong, if that helps.

    If you have your FFB mult set so that cornering forces are somewhere in the upper half of your available FFB, having a lower STS will make a change in those forces more pronounced.

    If the pedal overlay or other telemetry is showing a drop in FFB when you enter understeer, AND that FFB is above 50%, you can make that drop more dramatic by lowering STS. Conversely, if that FFB is considerably below 50%, you can make the drop more dramatic by raising STS. But anyone with a normal consumer wheel wouldn't have their forces that low because you can barely feel it.
     
    Euskotracks likes this.
  15. Euskotracks

    Euskotracks Registered

    Joined:
    Nov 29, 2013
    Messages:
    1,093
    Likes Received:
    191
    No. That's not the point of the suggestion.
    You started this thread saying that rF2 FFB was missing tire reaction. Something that apparently with AC you could feel perfectly. Now your latest sentence says you have no problem with FFB.

    I first proved that tires were affecting the calculated steering torque. I also checked how the different FFB modifiers affected the FFB% output which is what is being sent to the FFB device (wheel).

    All this has been done looking on telemetry and not based on sensations or visual representation of pedal overlay plugin which are for sure inaccurate methods of addressing a problem.

    I have asked you several times to check in the telemetry to see how each parameter really affects for the car you are using. You are stating that the only way to kind of feel the expected FFB drop is by reducing caster. As I showed in the study I made, this is because it provides a quite constant aligning torque throughout the whole speed range. You are also saying that you do not feel a significant difference between having the pedal overlay at 50% or 90%.

    So my conclusion, which would be better addressed if you had checked the telemetry, is that your hardware is clipping between 50% and 90% of its theoretical output.

    My second conclusion is that you don't really know if you have a problem and in case you have it, you don't seem to want to solve it. You have been asked to use telemetry to help in the diagnosis of the problem and you keep sticking to your sterile method which is not providing a single conclusion of where the problem is.
     
  16. Euskotracks

    Euskotracks Registered

    Joined:
    Nov 29, 2013
    Messages:
    1,093
    Likes Received:
    191
    Continuing with the above, what I suspect is that the linearity of your wheel is very poor. In the 100+ page long FFB thread,
    guide-optimal-ffb-settings-for-rfactor-2-the-key-to-being-in-the-zone-d.42931/, you can see several graphs of the real wheel output where the change of response in the higher end is very flat. Some of those graphs are with T500!
    t500graph1_zpsd394b45c.jpg
    The program to do that check is called wheelcheck.exe. In the long first post of the thread you will find the instructions to download it and to use it.

    Could you try it and report back your findings?
     
  17. green serpent

    green serpent Registered

    Joined:
    Feb 2, 2016
    Messages:
    625
    Likes Received:
    604
    Euskotracks, I started the thread, not Paul.

    I've downloaded the Motec i2 pro app, and also the data plugin. But I'm not as tech savvy as others here and it wasn't exactly easy to get it up and running. I've yet to do further digging to get it working.

    When I was referring to my tests using the pedal overlay, I said something along the lines of 'albeit unscientific test'. I was planning to go back and do it properly with proper data and a skid pad.
     
    Last edited: Nov 25, 2016
    Euskotracks likes this.
  18. Euskotracks

    Euskotracks Registered

    Joined:
    Nov 29, 2013
    Messages:
    1,093
    Likes Received:
    191
    You are absolutely right. My mistake. Apologies for the confusion.

    Regarding the instalation of telemetry utilities. I would recommend to install DAM plugin. It has a self installing exe and it can log FFB output which is not available for motec plugin (also from Lazza). You will only need to modify the DAM plugin ini file in player folder so that it logs all the available channels (everything set to 1).

    Motec i2 Pro is also straightforward to install. For the project template I can upload the one I have been using for my tests if you want.
     
    Last edited: Nov 26, 2016
  19. Euskotracks

    Euskotracks Registered

    Joined:
    Nov 29, 2013
    Messages:
    1,093
    Likes Received:
    191
    As you say at some point I got confused about your replies with green serpent. My apologies for it.
     
  20. Lazza

    Lazza Registered

    Joined:
    Oct 5, 2010
    Messages:
    10,788
    Likes Received:
    5,558
    And that's cool, and I don't blame you for that, because what we feel is often different to what telemetry says. For that reason, although you do talk a lot about what you feel, which again is fine, you can't dismiss telemetry and calculations if you're going to talk about using STS to adjust how the FFB behaves in a stated situation (or, you can just test for hundreds of hours, find a setting that feels good, and tell people that it does; but then maybe avoid discussions on how it works, or why its adjustment might change how a specific scenario feels).

    I'll briefly pick out a couple of things you said, just to try and keep clarity.

    That does reduce how much low STS will increase the delta, but it will still have an effect (again, check low sensitivity in the controls - you can see the curve at the mid point is steeper than the constant 100% curves). And, again in the context of the person struggling to feel dropoff with a low-end wheel (which is the context in which the suggestion was made to try lowering STS), it's more likely general steering forces are at least 50%.

    Probably more related to the response of your wheel, and/or your familiarity with the forces, rather than what STS is doing (what you've described goes completely against what I explained above about STS, and what you can see in the sensitivity curves you already indicated you understood - so if what you're feeling is correct, it's not because of STS).

    Forgive my scepticism; you can see, visually, that low STS like yours (probably roughly equivalent to sensitivity of 27% on the control graphs) will increase a representative FFB delta (say, a 15% drop) by let's say 20% at a minimum. So instead of dropping 15%, it drops 18%. You're saying you can't feel that, but you can (easily!) feel a 0.1% change in STS? I would suggest blind testing would prove otherwise. (off the top of my head, in fact, I'd suggest that if you were to test values of 0.265 and 0.285, in random order, across ~10 tests, you wouldn't be able to reliably pick which you were using)

    STS has no bearing on the timing of 'events', it simply (and only) adjusts how much force is output to the wheel. Low STS makes lower FFB values even lower at the wheel, and to do that the forces drop off more quickly from 100%, then flatten out more towards 0%. That's it, that's all.

    I believe STS is purely a step between calculated FFB and what is sent to the wheel. X in, Y out. I suspect you think it's more intrinsically linked to the dynamics of the vehicle, and may take trends or the physical situation into account somehow, and I think that's incorrect. Of course I could be wrong, I'm not a dev and my posts have my name on them because they're my opinion same as anyone else; but I also did some tests on STS vs FFB mult vs FFB output which showed that your conclusions about how STS worked based on what you were feeling were completely wrong.

    A change in STS might give you a certain feeling by the time the FFB goes through your wheel and you perceive it in the context of what you're 'feeling' with the car and seeing in the game, and I don't dispute that. I also don't feel any need to try and explain it with telemetry, because my involvement in this discussion was purely to explain why, and how, a change in STS would affect FFB in a certain way in a specific scenario.
     
    Euskotracks likes this.

Share This Page