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Recognizing locking and spinning wheels @ break/acc.?

Discussion in 'New users start here - FAQ' started by bberger, Aug 31, 2010.

  1. bberger

    bberger Member

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    I am wondering if it is possible to determine via X-Sim if the wheels are locking / spinning under breaking or accelerating.

    The reason I ask is as followed:
    I want to install 2 vibration motors at my breaking / acceleration pedals like it's done in modern car systems to warn the driver of upcoming dangerous situations. Such FFB feature would be a great addition to my custom pedal kit.

    Can anyone give me more information on this?
  2. Ads Master

    Ads Master

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  3. Frakk

    Frakk Active Member

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  4. jimiTES

    jimiTES New Member

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    Nima was working on that, but i think by now he can´t do a treshold event when locking wheels. It´s because there is no wheel speed info on Xsim plugins. rfactor can send this info but the Xsim plugin doesn´t request it. Maybe in future....

    If you have the wheel speed info, all you have to do is:

    If wheel speed<0,1 while current speed>0 then activate brake vibration (a digital output of the K8055 for example)

    If wheel speed>than current speed then activate gas pedal vibration
  5. bvillersjr

    bvillersjr Active Member

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    It depends on how much the wheels are spinning. It is correct that the best way to calculate this by comparing wheel speed to vehicle speed but this isn't currently possible given the data available to us. However, most wheel slippage results in wheel hop or shudder. Even high speed wheel lockups due to heavy braking result in shudder at the beginning of the slip and at the end of the slip when traction is lost / re-gained.

    If you a high amount of actuator updates per second, and are using a medium to high actuator acceleration rate with a fast actuator, you will be able to sense this in most games because it gets represented in the G-Forces. If you are using only Yaw, Pitch & Roll, then I don't think it's possible to get any of this sensation.

    So for your purpose, I would focus on fine tuning g-force effects to accomplish this. It won't be perfect, but it will provide an important cue at the beginning and end of wheel slippage.

    Another idea would be to try working with pitch acceleration values to see what can be extracted. I have never tried this, but have been successful in determining rear traction loss (sideways) using Yaw Acceleration.

    :cheers:
  6. jimiTES

    jimiTES New Member

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    But i think he is trying to simulate an ABS effect, isn´t it?
  7. bvillersjr

    bvillersjr Active Member

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    Simulating ABS is alot different than determining longitudinal (braking & acceleration) wheel slippage. His question was:
    ABS would be a constant pulsation. In theory ABS prevents the wheel slippage and may be a bit simpler to represent.

    The order of events in a heavy braking scenario without ABS would be:

    1. Wheel begins to loose traction (slight wheel hop or shudder usually occurs unless you just plant your brakes like a fool from a very high speed. In that case, you would likely slide like you were ice skating.)
    2. Tire is now sliding (Depending on the speed, road surface and vehicle, it will either glide smoothly, or have continued wheel hop.)
    3.) Vehicle begins to regain traction. At this transition between the slide and re-gaining of traction another shudder or wheel hop would occur.

    The portion of this process that can be accurately represented in a sim are steps 1 & 3 because this wheel hop shows up as a combination of longitudinal and vertical g-forces. The trick as I mentioned before, is to have a highly optimized syatem that can rapidly represent this cue.

    In a few months, I will have some more time to create another series of profiles and maybe a tutorial as well. I'm overdue for some seat time anyway.

    :cheers:
  8. Nima

    Nima Member Gold Contributor

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    hi,
    i make the brake feeling with position from the brake paddels multible with speed, working only over 30 kmh.you can make a littel hill effects on this.on hill down the wheel a look faster.
  9. bberger

    bberger Member

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    Nope, not really.

    I just want to activate a small mobilephone-vibration-motor on wheel lock under braking / wheel spin under accelerating on my gas resp. braking pedal. It's also used on modern japanese car development's to warn the driver if a dangerous situation is coming up.