GeoGebra model of GPB bike model

[BOBR6 84]

Yeah, to change the behaviour would be just fine! No chance of doing any 3d stuff haha

Just taking a look through the bike modding wiki, id like to figure out how to play around with the tyres.. Sizes, grip levels etc

So GeoGebra is used as a visual guide?

To be honest MaX, you are kind!  straight to the point.. I like it 

[BOBR6 84]

If I changed the tyres on the 600 from lets say 180/55 to 190/60 wouldnt it look strange in-game? Like a slight gap between tyre/track surface?

[HornetMaX]

So GeoGebra is used as a visual guide?

Yes, it was just a way to visualize the bike geometry when we had to figure out what the different geom parameters were.

If I changed the tyres on the 600 from lets say 180/55 to 190/60 wouldnt it look strange in-game? Like a slight gap between tyre/track surface?

If the overall tyre diameters stays constant you will have no gap.

Notice however that GPB tyres are not described as real life tyres (i.e. 180/55 R16).

The relevant parameters (for tyre size) are the tyre radius, the tyre torus radius and the "width" (which I suspect to be the half-angle of the tyre profile width, in fact).

Out of memory, for the 990 murasama, these are 325mm, 130mm and 60deg.

For grip levels: if you only want to alter the overall grip (on the different surfaces) that's pretty easy. Anything else is a bit trickier and you'll have to read about the Pacejka's MF model (the stuff displayed by MaxTyre).

BTW: that reminds me of an unanswered potential issue on tyres ...  http://forum.piboso.com/index.php?topic=1922.msg25790;topicseen#msg25790

MaX.

[BOBR6 84]

Thanks very much!

The pacejka formula is too complex for me. Doubt il make any sense of that but il take a look anyway.

For the tyre dimensions, Width.. So its measured from the top/centre?

Would be nice to undestand the tyre model but hey ho.. To adjust the overall surface grip levels that wont let me tune side slip and all that good stuff will it? 

Ps. Why no reply from piboso I wonder on your thread link? 

[HornetMaX]

For the tyre dimensions, Width.. So its measured from the top/centre?

As far as i understand it, the GPB tyre is a torus. With the conventions of the wikipedia page:

Code Select Expand

R is the distance from the center of the tube to the center of the torus,
r is the radius of the tube.

GPB has R+r = 325mm and r = 130mm (for the murasama).

To figure out the tyre widht, the only thing I can come up with is: the 60 indicates the half-angle of the tyre profile, i.e. the green angle in this post (here) is 2*60= 120 degrees.
If that's correct (but here too, it would be nice to have a confirmation from Pib) then the tyre width as we intend it (e.g. 180mm, 190mm etc) is computed as 2*r*sin(60deg) = 2*130mm*sin(60deg) = 225mm. That seems a bit big, even for a MotoGp tyre (officially, current Bridgestone are "only" 190).

Would be nice to undestand the tyre model but hey ho.. To adjust the overall surface grip levels that wont let me tune side slip and all that good stuff will it? 

No, to do that you'd have (at least) to play with the Pacejka model of the tyre.

Ps. Why no reply from piboso I wonder on your thread link? 

You search me.

MaX.

[BOBR6 84]

Nice one MaX! thanks very much.. good info  btw.. completely forgot about the tyre measurements  still want them??

[HornetMaX]

Nice one MaX! thanks very much.. good info  btw.. completely forgot about the tyre measurements  still want them??

Only if you have time to waste. Anyway they are only potentially useful if Piboso takes a look, so ... not exactly granted.

MaX.