Modifying the track is out of the question since the track can be (and =
is frequently)
redesigned and rented for use outdoors.  The track is built using 2x4 =
construction
and while in the store it is used on carpet, but when running the =
outdoor track
the cars run on pavement.  Mounting hardware to the track can be =
disasterious with
newbies running cars on the track (immagine hitting the reflector at 40 =
mph in a=20
$300 car, the person driving doesn't care cuz they just rented the car, =
but the company
would loose money fast).  Reaction time hasn't been a problem with the =
UltraSonic,
as I said I have it working now.  But I can't get it to work with the =
servos and=20
speed controls as I can't figure out how to create a PWM.  The idea of =
having the=20
ability to put it into any RC car is because people have started asking =
if they can
buy one for their car (I don't know why but hey if they want it and I =
can build it
why not sell it to them :).

Jeremy


-----Original Message-----
From: D. Jay Newman [mailto:jay@SPRUCEGROVE.COM]
Sent: Tuesday, July 01, 2003 8:30 AM
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [PIC]:Another newbie question JAL & PWM related


> to bring in business by driving the cars themselves.  But they get 3 =
times the
> business when they have a car on the track.  Initially I thought of =
using a
> pre-programmed course in the PIC but that was just to flaky since the =
car "Drifts".
> Beacons are no good because the mall and store noise drowns the beacon =
at times.

Have you tried some sort of "beacon" *under* the track? Something =
detectable
to short range RF or something like that.

However, because of the speed you need to have the car react *very*
quickly. I don't know how fast these cars can turn.

> RF beacons don't work because of the equipment used in the shop.  This =
leaves
> ultra sonic and IR.  IR can't be relied upon since the rubber off the =
tires on
> the side rails absorbs light (very painful to find that one out, =
trashed a car at
> higher speeds).

How about mounting bicycle reflectors every couple of feet on the side
rails? This should be detectable, and may be able to be used to help
a car run a preprogrammed course.

To keep the cars away from obsticles perhaps the various Sharp I/R =
Rangers
will work. As these are active they may work where more passive I/R =
doesn't.

> Anyone:
> I have the code in place to read the track and this project works
> fine with "It's Car" (Currently using normal motors with feedback from =
an encoder
> disk) but now I'd like to make it so that they can just drop it into =
one of their
> cars.  For this I need to figure out how to create 2 PWM controls on =
the chip.

Frankly, I'd use a special car, rather than dropping it into one of =
their's.

You could make the car have the same chassis configuration and just =
exchange
"bodies". (At least some of the R/C cars I know of have interchangable
bodies.) Even if you have to have a special set of bodies for the AI =
Car,
it would still appear to be different cars to the customers.

Good luck!
--
D. Jay Newman          !
jay@sprucegrove.com    ! Xander: Giles, don't make cave-slayer unhappy.
http://enerd.ws/~jay/  !

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