From: phaedrus@milton.u.washington.edu (Phaedrus)
Subject: Re: Thing's "Brain"
Organization: University of Washington, Seattle
Date: Fri, 31 Jul 1992 06:01:39 GMT

In article <6367@tekig7.PEN.TEK.COM> jerryc@tekig7.PEN.TEK.COM (Jerry C Carathers) writes:
>In article <1992Jul30.171051.16669@ncsu.edu> bcasper@eos.ncsu.edu writes:
>>
>>What is the deal with the AI for the Thing flipper in TAF?
>
>The "AI" is mostly software. An infra-red emitter/receiver combination tell
>the CPU when the ball is approaching the flipper. A default software timer is
>then triggered with a slight offset time determined by whether the ball
>frequently hits the swamp or the targets above or below it. This data is
>maintained in static RAM and can be reset with the "INSTALL NEW LOCATION"
>parameter.   

     You're missing one important point:  the machine can tell more than
"the ball is approaching the flipper".  The machine doesn't just see the
ball pass the sensor, wait some set time calculated from previous shots,
and then flip; if it did, it would be very inaccurate--there's just too much
variation from shot to shot in the speed with which the ball approaches the
flipper, so using a single calculated delay time would result in the flip
occurring too late on quickly-moving balls, too early on slow ones.
     By measuring the amount of time the ball blocks the optical sensor on
its way through, the game can use that sensor as a "speed trap," measuring the
speed of the ball as well as its position.  So it factors that speed info
into its calculations as well, resulting in much more consistent accuracy.  The
only thing the game still can't measure is the side-to-side movement of the
ball as it comes down the lane; the variation this side-to-side movement puts
into the position of the ball at the flipper keeps the game from being even
more accurate than it is now.
     By the way, it's not necessary to use the INSTALL NEW LOCATION utility.
Here's how you can do a recalibration without messing with the software 
switches at all:
     1. Remove the playfield glass and start a game.
     2. Throw the ball up the Million+ ramp four times.  (I have no idea what
this accomplishes, but the manual tells you to do it and I'm certainly not
going to argue. :) )
     3. Press the Thing Flips sensor in the left inlane to set up Thing Flips,
then throw the ball up the Bear ramp to set it off.  When the ball comes back
down and the Thing flipper flips it, catch the ball before it can reach the
Swamp targets.  Do this sequence (sensor, ramp, catch) a total of four times.
Four such consecutive total misses automatically clears the Thing Flips
calibration info.
     4. Now, to do the actual recalibration, press the Thing Flips sensor,
throw the ball up the ramp, and let Thing flip the ball without you catching
it.  Keep repeating this sequence, pressing the sensor and throwing the ball
up the ramp at different speeds.
     After twenty or so of these recalibration throws, the machine should be
becoming pretty accurate; you should now be able to return the machine to
normal play, and it will do the rest of its learning on its own.

     (Most of this information comes from reading the manual, and from talking
to my friend at Williams; all errors are my own responsibility, of course.)
-- 
Internet: phaedrus@u.washington.edu        (University of Washington, Seattle)
 "If you can keep your head while those about you are losing theirs,
    consider an exciting career as a guillotine operator!"