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Pacejka tire coefficients
10-04-2010, 03:47 PM,
#17
 
Slip ratio is combining, and is similar to beckman in that it manipulates the combining ratio based on pre-friction force information (the slip rates). It is cruder than beckman.

For a dynamic contact patch sim, which you don't have at the moment, you do need to run a much higher frequency. The 600hz you run the tires at now gets you decameter resolution at speed. You need cm resolution for a good dynamic contact patch.

However, the problem you cite is not a really a tire friction modeling issue. It is a more general integration issue, made worse by the fact you are stuck with explicit integration. And you will continue to be stuck with it at the core chassis level since you are coupling to a third party MB solver (bullet). I don't think this is a problem though. At 600hz, at the frequency the tires react at the car level, you should actually be fine...if you had the amount of damping on your tires that real tires do. In my little refactor I added damping. You have 1e5 spring rate hardcoded. About 1e3 normal ol viscous damping does the trick for me.

Yes, the easiest way to fix beckman is to zero out the horizontal and vertical shift components in your Pacejka parameters. Honestly, those parameters are not worth much in the big picture given how much is already being approximated by using a steady state model in the first place.
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Messages In This Thread
Pacejka tire coefficients - by NaN - 04-19-2010, 03:08 PM
[No subject] - by joevenzon_phpbb2_import3 - 04-20-2010, 10:48 PM
[No subject] - by orangutan - 08-19-2010, 06:21 PM
[No subject] - by joevenzon_phpbb2_import3 - 08-19-2010, 11:48 PM
[No subject] - by orangutan - 08-20-2010, 10:03 PM
[No subject] - by thelusiv - 08-22-2010, 06:22 AM
[No subject] - by orangutan - 08-30-2010, 06:02 PM
[No subject] - by thelusiv - 09-02-2010, 06:50 PM
[No subject] - by orangutan - 09-05-2010, 02:14 PM
[No subject] - by joevenzon_phpbb2_import3 - 09-11-2010, 10:12 AM
[No subject] - by orangutan - 09-20-2010, 03:02 PM
[No subject] - by orangutan - 09-29-2010, 02:31 PM
[No subject] - by orangutan - 09-29-2010, 08:56 PM
[No subject] - by orangutan - 10-01-2010, 01:21 PM
[No subject] - by orangutan - 10-01-2010, 05:23 PM
[No subject] - by joevenzon_phpbb2_import3 - 10-04-2010, 10:37 AM
[No subject] - by orangutan - 10-04-2010, 03:47 PM
[No subject] - by NaN - 10-06-2010, 06:08 PM
[No subject] - by orangutan - 10-07-2010, 08:36 PM
[No subject] - by NaN - 11-23-2010, 05:10 PM
[No subject] - by fudje - 11-24-2010, 05:48 AM
[No subject] - by NaN - 11-24-2010, 10:33 AM
[No subject] - by NaN - 11-25-2010, 11:20 AM
[No subject] - by NaN - 11-25-2010, 12:31 PM

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