Re: Patch for wheel spin velocity traction

Hi David

It makes in my opinion no sense in respect to the tire model, the slip 
definition looks consistent as is for me (in your analysis there is a 
little glitch, vt is not the car velocity, it is the wheel specific 
velocity, all wheels have usually at least slightly different velocities).

The proposed change would cause a discontinuity which would usually 
lower the grip.

I think a better solution for drifting is to adjust the parameters of 
the tire model , differential and suspension. If you don't mind to edit 
the XML you can adjust as well the engine braking coefficient (instead 
of adapting your accelerator control in your mind;-) ).

Other opinions?

Kind regards

Bernhard

On 03/27/2015 07:29 PM, David Savinkoff wrote:
> Hi Bernhard,
>
> Please apply this patch; which makes for better maneuvering while
> drifting and overtaking in corners.
>
> What I found interesting with the line of code:
> sx = (vt - wrl) / fabs(vt);
>
> Is that:
> sx = (car_velocity - wheel_spin_velocity = slip_velocity) / car_velocity;
> Has no [units] and is 'with respect to' car_velocity.
> This works well with braking because the wheel_spin_velocity is less
> than the car_velocity.
>
> When wheel_spin_velocity is faster than car_velocity, it appears that this
> unitless value works better with respect to wheel_spin_velocity.
>
> Thus:
> sx = (vt - wrl) / ( MAX(fabs(vt) , fabs(wrl)) );
>
> Sincerely,
> David Savinkoff
>
>
>
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