Sim Racing servo ffb systems : OSW & Bodnar

Discussion in 'General Discussion' started by Adrianstealth, Jun 1, 2015.

  1. DrR1pper

    DrR1pper Registered

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    Then where is the energy coming from to provide the resultant change in angular momentum and angular kinetic energy that is perpendicular to the steering axis when someone applies a torque to the steering axis of a spinning wheel?


    Edit:

    I also think i figured it out how/why the contributions to a heavier/stiffer steering wheel feel due to gyroscopic effect in a car occurs. For the on-ground scenario, when a driver inputs a steering torque, any gyroscopic effect will try to induce a camber change in the wheel. But this will be resisted by the ground and geometry of the struts holding the wheel in place, etc. This resistance in turn acts like a torque input being applied to the wheel (but occurring about the camber axis of the wheel/tyre) and thus a corresponding 90 degree out of phase action occurs which is now in alignment with the steering axis. The resultant direction of this return action is in the opposite direction to the drivers initial/original input torque to the steering axis.

    Though if this is correct, it would then seem like it should also occur in the off-gound scenario too since the camber of the wheels cannot change due to the rigidity of the wheel struts, etc, thus should be feel-able through the steering wheel by the driver. But it won't because the resultant angular momentum change through the camber axis of rotation will be transferred to the entire car's body of mass and thus roll the car and not return to the steering axis. Thus technically, turning the steering wheel in such a scenario would cause some amount of change of angular momentum in the roll axis of the car. Though whether you would/could sense it or not…different discussion. My guess would be not since the moment of inertia of the wheel/tyre is insignificant compared to that of the entire car.
     
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  2. Euskotracks

    Euskotracks Registered

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    you don't need energy to change angular momentum direction. You only need provide energy if you are changing the angular momentum magnitude

    Enviado desde mi GT-I9505 mediante Tapatalk
     
  3. DrR1pper

    DrR1pper Registered

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    But isn't that exactly what is happening? I.e. you input a steering torque to the steering axis of a spinning wheel and some amount of gyroscopic effect will happen (because it's spinning) that will cause the wheel to increases in angular momentum magnitude in the axis that is perpendicular to the steering axis and spin axis of the wheel. No?

    edit: please re-read, made an error when referring to an axis.
     
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  4. Euskotracks

    Euskotracks Registered

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    the gyroscopic torque cannot absorb energy since there is no angular displacement in that camber axis because it is constrained and hence no angular momentum can be established around that axis.

    Enviado desde mi GT-I9505 mediante Tapatalk
     
  5. DrR1pper

    DrR1pper Registered

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    ok, so my edit in post 252 has to be wrong. Not sure what i was thinking at the time but if you follow the logic i put forth there you actually end up with all the energy from steering input returning to the steering axis in the direction the driver wants…not in the opposite direction i stated it would.

    You're saying the energy cannot be absorbed through gyro effect (because the camber cannot change) but even if so, something must be or else you'd also be saying the gyroscopic effect does not contribute to the stiffening of the steering wheel with higher speeds.

    Therefore i was thinking even if no angular momentum change can occur in the camber axis (i.e. the wheels are rigid relative to the car body), it can/will be transferred to the entire body of mass of the car which will act to shift the lateral weight balance of the car. That's where the energy can be absorbed (or stored and dissipated in the suspension, chassis, etc).

    You can visualise for a motor bike, at sufficient speed when applying a torque on the steering axis, the gyro effect acts to lean/tilt the bike. E.g. applying a force on the left handle bar (i.e. in the direction of steering right) without changing the steering angle = motorbike leaning left due to gyroscopic precession effect. Now imagine two motorbikes side-by-side rigidly welded together and the steering axis joined to act in sync, the same application of force on the left handle bar without changing the steering angle will result in a torque (or more correctly an angular momentum change) acting to lean the two bikes left. But the bikes are welded rigidly together so the net torque action will simply shift the lateral weight balance to the left (unless the roll torque is greater that the torque action of gravity trying to keep all four wheels on the ground.)
     
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  6. Korva7

    Korva7 Registered

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    Okay, when car's leaning movement is taken into count it seems like gyro effect can absorb some energy because displasement is happening (in wheels leaning angle). But i think that the energy absorped is force x displacement and that it is not stored in chassis and suspension.

    There is also wheel aligment things (caster) stiffening steering with higher speeds, but that stiffening is spring like instead of damping like.
     
  7. Korva7

    Korva7 Registered

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    Is it normal that i need to put ffb update rate down to one third (133 hz) from the normal (400 hz) to make OSW wheel feel good?
    Otherwise the ffb feels artificial. It feels like the ffb has bad (sound) quality. It feels the same as distortion sounds.
    With lower update rate it feels very good, but i still wonder if i have something wrong with my other settings.

    Granity settings, Disco flashing and things like that was already done to the hardware when i got the system.
    So far I have tested changing ML, MR and TBW (Torgue bandwith) values from granity. TBW seems to be the same thing as ffb update rate in rF2's controller.json
    ML, MR didn't seem to have effect to the problem.

    I also put overall filter from Mmos to 31 (full) but it didn't remove the problem.

    Is there anything else i can try?
    I'm pretty happy with the wheel with that lower update rate, but i wonder if this is normal?

    OSW: small mige + argon.
     
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  8. Adrianstealth

    Adrianstealth Registered

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    You've had to do this ?

    Is this the case with OSW - rf2 ?

    Didn't have to do this with my bodnar but I do have to ament the rf2 ffb file otherwise my wheel seems locked in one position

    Be good if another user if the OSW could confirm on the rf2 MHz adjustment
     
  9. Korva7

    Korva7 Registered

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    Also if TBW from granity is set higher than 150 hz i get crunching and unwanted vibration when testing MMos deskop effect damping.
     
  10. DrR1pper

    DrR1pper Registered

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    How did you come to the 133Hz value? Trial error?
     
  11. Korva7

    Korva7 Registered

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    FFB update rate setting in controller.json is like this.

    Skip updates":0,
    "Skip updates#":"Apparently some drivers can't handle a quick FFB update rate, so use this hack to skip the given number of updates
    (0=full update rate, 1=half,2=one-third, 3=one-quarter, etc.)",

    Yes, by trial and error I found out that setting (1=half) wasn't good yet, but with (2=one-third) there was no problems any more.
    And i read that rf2 update rate is 400 hz so one-third from that is 133 hz.

    I just found out that ticking CIS (Setpoint smoothing) from granity's settings cures all the problems i mentioned. With it ticked i can use full update rate from rf2 setting and TBW (torgue bandwith) above 400 hz from granity's settings.

    Granity wiki says it is: "250Hz low pass filtering of setpoint signal."
    So it's higher than that 133 hz but wiki also says that: "CIS adds about 6 ms delay to setpoint reaction speed."

    I have to continue testing to find out which one (133 hz vs. CIS) works better.
    OSW tutorial says it is better not to use CIS, but in tutorial's granity screenshots it is ticked.
     
  12. DrR1pper

    DrR1pper Registered

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    ok, cool, glad you're on the right track.
     
  13. Katsushika Matsumoto

    Katsushika Matsumoto Registered

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    Hi korva let me know how I can check those settings, I only used mmos FFB tool so far.
    rF2 feels good to me without tinkering with any settings.
     
  14. Korva7

    Korva7 Registered

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    Do you mean granity settings? The rf2 update rate is at 400 hz if you haven't changed it, so there is no need to check that.

    To see granity setting you would need to download Granity V1.7.0 software, and connect argon to computer using USB to RJ45 Adapter, swich argon on, open granity software, and press connect to drive.
    It's a bit of a hassle, and i already sent email to Dennis Reimer about this (i bought the system from ib-reimer.de) so maybe there is no need for you to see that effort because of me.

    I was just reading virtualracing forums (which are all in germany) with google translate and there seems to be some settings that aren't straight at the granitys UI.
    I need to press ctrl + p and do something. I will test that later.
     
  15. Katsushika Matsumoto

    Katsushika Matsumoto Registered

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    Ok let me know, I also bought it from Dennis so we probably have the same settings :)
    Interested to see if I can improve the feel even futher :)
     
  16. Korva7

    Korva7 Registered

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    Okay that is very interesting, if we have same granity settings and your wheel works well with full update rate and mine doesn't. How much filter you use?
     
  17. Katsushika Matsumoto

    Katsushika Matsumoto Registered

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    Same settings as I use for GameStockCar, only with 900 degrees steering.
    Apparently Niels (of Reiza) uses these with 46% strength in game, so I'm told.

    Ps. I'm also able to run fine with all filters off, but this feels slightly better.
    Pps. With rF2 I use MMos @ 100%, FFB multiplier at 1.00 and 0% min. force, with 20 (NM) in the controller ini.

    osw-gsc.png
     
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  18. Katsushika Matsumoto

    Katsushika Matsumoto Registered

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    I reread you comment, do you mean like there is sand grinding in the motor?
     
  19. Korva7

    Korva7 Registered

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  20. Katsushika Matsumoto

    Katsushika Matsumoto Registered

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    I had the same in feeling in GameStockCar at first.

    In which car in rF2 did you have this effect/feeling?
    I think I don't have the feeling with i.e. the NSX, can check tonight.
     

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