[ODE] Re: Simulating Wheels

[Steve Baker]

Dave Lloyd wrote:

>> I agree - to a certain extend. Even if you could input Nm/s2 and stuff -
>> which numbers would you put in? I'm sure you'd have to experiment anyway.

I estimated the spring stiffness of my MINI Cooper to be 25,000 N/m on
the rear springs and 67,000 N/m on the front.   I did that by sitting
on the car in various places and measuring the amount by which the
suspension compressed. I did this knowing the mass of me and of the
car and knowing from the specifications that the MINI has 70% of it's
weight supported on the front wheels and 30% on the back.

The MINI has a light body and an extremely stiff suspension - and it's
heavily damped too - so these numbers aren't likely to be typical.

>> Springs and dampers is no hokus - if it's too stiff, make it softer, if
>> it's too soft - make it stiffer. Make the parameters adjustable as you
>> drive and adjust them until you're happy. No problem.

Well it *is* a problem if you are trying to reproduce the handling of
a specific car (as I do) - and you want to predict the effect of doing
things like putting lowering springs onto the car or putting more viscous
oil in the shocks.

Just tweaking it until it seems right isn't going to cut it.

---------------------------- Steve Baker -------------------------
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