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Engine and wheel inertia
07-27-2009, 12:24 AM,
#20
 
stan.distortion Wrote:I was thinking the same at first but got my head around some of whats happening from using cout with GetDisplacement for each wheel, the springs are compressing properly with roll and acceleration forces and, as for as I can see, the inertia is getting taken into account but the body is just sitting level.
Just been messing around with the rates on the C7 again, it's hard to get an idea of where to start with the settings (hence 3 days trying to get body roll Smile ) but it seems right, its wallowing like a sick hippo. Here's the horrendous bodge I stuck on the end of ApplySuspensionForceToBody

So you're basically just delaying the suspension force by one frame? I can't imagine that would have a huge difference. Did you try using your tuned C7 file with the original (current SVN) suspension code? Because when I tried your C7 file, voila, I got healthy body roll without having to touch the suspension code.

Quote:BTW, did you get a chance to look at the square root stuck on the damper force calc's ? It's ugly and relies on no integration to avoid launching the car on small bumps but it stops the car doing acrobatics when touching a curb on the ring or pau. I will look into adding a fast rise in the spring rate near the top of travel to simulate bump stops before too long, but first...

I plotted it and it does look a lot like the general shape of the shock dyno you posted. I tried it out in game and it seems to work fine. But I think the ideal solution is like you said, define points in the car file like how the torque curve is done -- the steepness of the sqrt function around zero kind of bothers me, but the cars drive great.

Quote:Now I have some kind of body roll I'll get right onto it before poking at anything else, even if the roll changes from some proper coding the change should be fairly linear and just mean scaling the rates up or down. No idea what to do with the tires though, probably need a few more dead chickens to wave. Do you have any notes on the formulas used for the tire calculations? I want to do up a spreadsheet to visualize what does what and my head is already spinning from trying to follow object orientated things.

There's a basic textual description of the different coefficients here:
http://wiki.vdrift.net/Car_parameters#Tire

But this is the best resource I've found for understanding what the different coefficients actually mean:
http://members.xoom.virgilio.it/adiaforo/epcjk.htm

Also, if you can find a pacejka editor so you can visualize how the curve changes with different values, that helps immensely as well. The coefficients for the 360 are a good starting place because it sets many of them to zero.

Parts 21 and 22 here might help:
http://phors.locost7.info/contents.htm

Quote:Couple of other thoughts to finish of an already too long post:
When you suggested the formula to get wheel inertia from wheel weight, does that look about right to you now? A value of about 2 is working well for me here, might not suit everyone though...

The wheel inertia formula is correct, although it assumes constant density over a cylinder. There's also a formula for a cut out cylinder that may give better values:
http://en.wikipedia.org/wiki/List_of_moments_of_inertia
Iz=0.5*m*(r1*r1+r2*r2)

Also add a little more onto the value for the inertia of the axle.

Quote:Along with the damper and bump-stop I'd like to add damper fade to the suspension force code. It's simple to do but would need a .car file entry to be useful. Brake fade would be more or less the same code, and they both pave the way for tire temperature...

Oooh... :-)
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Messages In This Thread
Engine and wheel inertia - by stan.distortion - 07-16-2009, 02:32 PM
[No subject] - by stan.distortion - 07-16-2009, 06:26 PM
[No subject] - by stan.distortion - 07-17-2009, 01:01 PM
[No subject] - by joevenzon_phpbb2_import3 - 07-17-2009, 06:40 PM
[No subject] - by joevenzon_phpbb2_import3 - 07-17-2009, 07:00 PM
[No subject] - by joevenzon_phpbb2_import3 - 07-17-2009, 07:02 PM
[No subject] - by stan.distortion - 07-18-2009, 09:30 AM
[No subject] - by joevenzon_phpbb2_import3 - 07-18-2009, 08:12 PM
[No subject] - by stan.distortion - 07-19-2009, 09:12 AM
[No subject] - by joevenzon_phpbb2_import3 - 07-19-2009, 03:20 PM
[No subject] - by stan.distortion - 07-19-2009, 04:21 PM
[No subject] - by stan.distortion - 07-19-2009, 05:03 PM
[No subject] - by joevenzon_phpbb2_import3 - 07-19-2009, 11:20 PM
[No subject] - by stan.distortion - 07-21-2009, 04:05 PM
[No subject] - by stan.distortion - 07-22-2009, 04:47 PM
[No subject] - by stan.distortion - 07-22-2009, 08:53 PM
[No subject] - by joevenzon_phpbb2_import3 - 07-22-2009, 10:26 PM
[No subject] - by stan.distortion - 07-23-2009, 02:33 AM
[No subject] - by stan.distortion - 07-23-2009, 04:39 AM
[No subject] - by joevenzon_phpbb2_import3 - 07-27-2009, 12:24 AM

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