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Re: Extreme GEEZ opinions?

To: Jeff Cashmore <cashmo@spec-rx7.org>
Subject: Re: Extreme GEEZ opinions?
From: Byron Short <bshort@AFSinc.com>
Date: Mon, 25 Mar 2002 16:57:02 -0700
What you might be thinking about is the transition to
brakes.  This is handled as a transition rate, and all
transition rates are lumped together.  This can make it hard
to not get a red spot (on a Usage color scheme) when you
transition from gas to brake.

Your peak transition rate is usually in a slalom, or slalom
type manuever.  In those cases, a car that pulls 1 g in the
slalom and runs a 1 second cone to cone time, will usually
peak up around 3.5-4.0 g/sec transition rate.  This is
pretty snappy.  Transitioning to braking usually isn't that
snappy, so the result can be a red spot.

This is an improvement over the previous method.  Previously
transitions were only measured in the lateral plane.  We
never bothered to calculate transitions longitudinally at
all, so the result was worse because as you transitioned
from gas to brake you got a Usage of zero as you passed
through 0g of longitudinal acceleration.  Under the new
method you might get only 75% or 50% or whatever, if you are
transtioning at 2g/s or 3g/s (using our 4g/s max from
above).  In fact, we now measure transitions in any
direction.  You might go from gas-left to brake-right, and
we calculate a transition rate on that.  

Actually, Jeff, I think I made this change in response to
YOUR input.  The old way gave huge red spots on your braking
transitions.  The new way makes them either smaller, or in
some cases disappear.  It's still likely that you'll
transition to brakes more slowly than you'll snap the car
through a slalom, but the color coding more correctly
indicates just what the heck you are doing with your
transition rates, regardless of the direction of the
transition. 

We also use this  transition rate stuff in calculating
Aggressiveness ratings, btw.

--Byron

Jeff Cashmore wrote:
> 
> > My biggest problem was coasting into turns. This really showed up, usage 
>would fall like a rock about 1/2 sec before the curve, DOH!! You can also see 
>if you are doing good transitions and using the brakes well.
> 
> I seem to remember that everyone's usage will go down under braking.
> Something about one of the calculations.  Am I way off on that thought?
> 
> Jeff

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