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Re: How does GEEZ calculate usage?

To: "geez@autox.team.net" <geez@autox.team.net>
Subject: Re: How does GEEZ calculate usage?
From: Todd Green <tag@cs.utah.edu>
Date: Tue, 02 Nov 1999 09:28:43 -0700
>Wow!  Geez tracks the actual peak point for every point on the friction
>circle (tube)!?!?  That seems somewhat improbable... OR, does Geez have a
>standard formulation for how tires vary with respect to the angle of force
>and then computes based on the peak lat, accel, braking forces?

Where o' where could our Byron be?  Seriously, all we are doing is
speculating.  Only Byron knows the algorithms employed by GEEZ.
However, I'd imagine that you'd quantize it, much like you quantize the
"friction cylinder".  Say to the nearest degree.  That'd only be 360
values to store which is nothing on a PC, and feasible on a Palm.

>Whoa--- now how would Geez figure that out?  How would it know whether
>the course was wet or you were just not handling the elements on that
>side of the course very well?  Somehow I don't think Geez is that clever.

I doubt that GEEZ does this.  But I would imagine that you could pass
the data through a fourier transform and look at it in the frequency
domain and find some telltale characteristics.  I'd imagine that the
deviation from the mean will be much greater if you are just not driving
well, whereas your absolute peaks will be lower if there is just less
grip out there.  However sampling theory isn't my speciality. ;) But a
nice channel to add to GEEZ would be a histogram of time spent pulling
lat and long g's.  In theory, you should be able to look at two runs and
whichever run has the area maximized under the curve will be your best
run.

>Agreed... and as I said before, I think you'd need two rates there, as
>you can go from max accel to max brake much quicker than vice-versa.
>But why do you think Geez doesn't look at that?

Look at your usage on any straight line braking.  When the accel graph passes
through zero, your usage will drop dramatically.  That and the fact that
there isn't an accel/time channel is a good tip :)

However M(r.) Sipe brought up a good point in that we could be trying to
dig too deep with GEEZ.  Instead of hyper analyzing each datapoint we
should be looking for trends.  Do I enter corners well?  How am I
holding the car at the limit in sweepers?  Do I exit well?  How am I
doing in slaloms?  Pick the area in which you are doing the worst, focus
on it, improve it, and then move on to your next weak area.   I think
this is good advice. 

Todd

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