New tire model? (idea)

Discussion in 'Ideas and Suggestions' started by bluehawk360, Mar 14, 2020.

  1. bluehawk360

    bluehawk360
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    As the title suggests, I have an idea on how to improve the current tire model. Currently, each tire relies on a set of nodes in a circular pattern on opposite ends of the wheel. The issue with this is that it does not accurately represent a tire under extreme forces.

    With the current tire model, when the tires are spinning at fast speeds, the tire would deform out in the center. (See here for example: )

    Currently the tires just grow in size at all edges of the tire. Even going as far as stretching the rims as they do not have separate nodes.

    My idea to improve the tire is to add a third set of nodes around the wheel, in the center of the tire. Assetto corsa competizione changed their tire model to a similar model (5 point tires) a few months back and it has vastly improved the handling of vehicles. An example on why this is great can be found here: https://www.assettocorsa.net/forum/...oducing-the-5-point-tyre-model-for-acc.59307/
     
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  2. Goosah

    Goosah
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    BeamNG Team

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    We have tried adding extra nodes (masses) in both in the sidewall and tread in experiments, but the handling suffered, and the total amount of wheel expansion at speed increased too. The results of our experiments produced tires that were good for low speed, off road driving only, aside from being more computationally expensive. Our tire model is a live mass spring network. Adding more masses to the wheel would make the tire more flexible with more points of contact, it would also mean that the overall structure must become less stiff. Because each individual mass has to be lighter to achieve the same overall weight, the springs have to be softer to remain numerically stable. For now we will continue to optimize the current structure.
     
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  3. bluehawk360

    bluehawk360
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    Is there any other way to simulate tires other than nodes? Or what about adding a non-node based tire on the inner side that can help to maintain contact with the ground.
    I'm sure there are cons but you could still add a few nodes with higher density or weight (i'm not sure 100%) that can still give a vehicle in air rotational gyroscopic forces

    Please keep in mind that these are simply my ideas but if any of them can help to improve the tire model, I'm more than happy to take a bit more time to do research on tire models and other possible ways to improve BeamNG's model.
     
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  4. bluehawk360

    bluehawk360
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    The thing is, the tires don't seem to grip up like a normal vehicle. Correcting a slide when done incorrectly can easily send the car into a spin. Beam just doesn't feel like it does that properly. I don't know if the tires simulate surface tension, but that plays a huge role in whether or not the tires can remain under grip. I'm also unsure if the nodes bounce slightly after the tire rolls onto them. This can cause a lack of grip as well.

    Overall, there are many different things that can affect the tires, and i'm unsure of how well the current tire model simulates those things.
    --- Post updated ---
    Upon more testing in game, while i'm not 100% sure, I have concluded that tires (at least on the Ibishu 200bx) handle better when put at 5 PSI over the default 30. My belief is that this is caused by more nodes coming in contact with the ground, but I can't be certain as the lower PSI causes slightly more flex in the tire's sidewalls.

    I tested this by duplicating the same vehicle and changing PSI for one, then setting the car at 100% steering lock and finding the perfect throttle amount to put the tires at their grip edge. Then with the second, attempt to follow the same circular radius at the same speed (which I found impossible with the higher PSI version)

    *Edit
    More testing:
    Putting them side by side and pausing the game. Full throttle for both, Unpause, and the Lower PSI vehicle Always wins at acceleration. Top speed is reduced for lower PSI vehicle
    --- Post updated ---
    Even more testing:
    Braking distance for low PSI model is greatly decreased.
    How:
    Set both vehicles (one at a time) to second gear and full throttle to redline. Cone as braking point (slow motion for more accurate timing) and release throttle and full brake. (ABS is enabled)


    Once again I assume this is caused by more nodes being in contact with the ground.

    Edit: More info

    This does not seem to help with Low profile tires I.E. ETK-K series tires
     
    #4 bluehawk360, Mar 21, 2020
    Last edited: Mar 21, 2020
  5. Yota

    Yota
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    This happens in real life too. Lower pressure generally means a larger footprint, so more grip. The issues (and reasons why we run car tires at 30ish psi) aren't simulated that well, or sometimes not at all. Sidewall rigidity goes out the window, and you can unseat the tire bead while cornering. You'll also see a decrease in fuel economy and improper tire wear.
     
  6. bluehawk360

    bluehawk360
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    Even so, the tires in BeamNG still feel as if they are over-inflated causing a much more sudden loss of grip and lower grip overall
     
  7. Yota

    Yota
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    Eh, yeah maybe. I think it's about perspective. I'm no racing expert, but I don't believe you can carry more than about 60mph thru a sweeping turn and about 50 thru a 90┬░ish turn. I always find myself trying to corner at 80mph and spinning out, but I can turn just fine at that 50-60mph range. When driving my real car I generally don't do more than switch lanes at 80mph. I did some experimenting, nothing worth posting. I found that the new "crawler" tires (I tested with the 38 inch variant) are much stiffer than I would expect. They actually support the weight of a D-series (standard cab short bed) at 0 psi! That would lead me to believe they are modeled after bias plys, but even then they don't seem to balloon like a real bias ply would.

    I'll say that the BeamNG tire model is the best around, and they're always trying to improve it.
     
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  8. bluehawk360

    bluehawk360
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    I know that recently they revamped the tire model and gave it a stiffer sidewall to help with force feedback. Idk if this is causing issues with the way the tire behaves under extreme forces though. Beam's tire model as a whole is very good. Simulates much better than most other sims, but it also lacks in other areas. The current tires might be only having a small surface area touching the ground which is causing the tires to behave this way. Go into any realistic sim with a controller and you'll find that the cars typically "snap" back and forth if you aren't extremely careful and smooth with your movements. (throttle control is another factor) Beam just doesn't do this like other sims. You can get the snap oversteer, or a little bit of snap, but you'll never be able to whip a car around like other sims. I know this is kinda like comparing apples to oranges, but there's a significant difference in the way the tires perform in a vast number of sims.
    --- Post updated ---
    I do definitely believe that surface tension needs to be added to vehicles or increased. Tires can handle more forces when under grip than when having a loss of grip. Think of a book on a table. Push it with one finger. It takes a certain amount of force before it begins to move. But once it's in motion, it's easier to maintain the motion regardless of the greater friction.
     
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