Re: A simuv2 backport of the clutch/gear-change inertia fix

Hi,

Christos Dimitrakakis schrieb:
> On Thu, 10 Jan 2008 09:54:59 +0100, "Frieder Ferlemann"
> <[email protected]> said:
>> Hi,
>>
>> Christos Dimitrakakis schrieb:
>>> It is not clear how to determine braking from the engine parameters, 
>>> which is why we have 'engine brake' parameter F.  From what you say, I 
>>> think that if F is set correctly according to each engine, the model 
>>> type (a constant + linear factor for braking) is adequate and the only 
>>> question is how to determine F.
>> If the engine inertia is known and one has the sound of the engine
>> rev'ing down while the clutch is open one could try to derive it
>> from there. Probably would work well for non-turbo engines?
>>
> 
> Sure, but there are difficulties:
> 
> 1) Collecting the data.
> 
> 2) Estimating the rpm from the sound.  I have tried that in order to
> convert engine sounds to the steady-rpm we need for the game.  It's not
> easy.  It's probably best to create a statistical inference model that

One could try to use FFT (Fast Fourier Transform) and visualize the results
as it's sometimes done with whale songs.
I searched a while for a nice link and didn't find a nice one, maybe
the figure here shows well enough:
http://www.baudline.com/
>From the position (and the shift) of the lines it might be possible
to derive the RPM (over time) from a given sound file.
No idea how good that would work for engine sounds.

> directly infers a constant and a linear deceleration parameter from the
> sound data.
> 
> 3) This procedure will only give you the friction up to a multiplicative
> factor.  Resolving this will require knowledge of the engine inertia. 
> This will require data from revving up and matching it with the known
> torque of the engine.

Yes, major problem.

> I used the following simple method to setup a car that is similar to the
> one I drive:
> 
> 1) Count the time needed to revup to redline
> 2) Count the time needed to revdown to idle.
> 
> Tweak inertia to fit revup time.  Tweak friction to fit revdown time.

Yes.

Greetings,
Frieder

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