Date: Fri, 16 Jul 93 13:00:24 EDT
Message-Id: <9307161702.AA23530@runner.Kodak.COM>
Comment: Discussions of Robot controller boards
Originator: robot-board@oberon.com
Errors-To: gkulosa@oberon.com
Reply-To: hysell@Kodak.COM (John D. Hysell)
Sender: robot-board@oberon.com
Version: 5.5 -- Copyright (c) 1991/92, Anastasios Kotsikonas
From: hysell@Kodak.COM (John D. Hysell)
To: Multiple recipients of list <robot-board@oberon.com>
Subject: a few more test-bed details

Wow!  I really didn't expect that much interest in hacking up a test-bed out
of an old Xmas toy...  Given the number of direct mail inquiries, I guess I
might as well broadcast some more details.  (A few of you may recognize the
following from direct mail responses - sorry for the re-run).

I have been encouraged to send along photographs as well; that will take a
little effort.  I will try to zap a few this weekend.  I expect I will
include some UUENCODED GIF files; will that present anyone with viewer
problems? (I can probably convert to other formats at this end if you cannot
deal with GIF.)

Here's a quick summary of test-bed #2.  (Test-bed #1 is a collection of LEGO
creations, none of which hangs around long enough to be photographed...)

   The Mobile Armatron is a cute toy peddled by Radio Shack (Not sure if it's
still available - best time to see is around Xmas) that has 2 drive motors on
a base with a 3rd wheel on a swivel for steering.  Attached to the base is an
arm with shoulder, elbow and wrist joints.  The elbow can be set to various
angles manually, while the shoulder and wrist are controlled via 3V DC motors.
The wrist also rotates, and a simple claw 'hand' opens and closes.  The 5 
motors are controlled from a handheld device that is tethered to the base.

   I added the LEGO cubes to the 4 corners of the miniboard (used a hot-melt
glue gun to secure them).  I pop flat LEGO parts on all the test-beds, so I
can move the miniboard from one to another easily, and still have a secure
wiring arrangement.  (I guess I never outgrew my like for LEGO; I have to
share them with my 2 kids now...)

   The Mobile Armatron uses 4 D cell batteries as 2 3-volt power supplies. 
The tether controller connects the various drive motors to the postive or
negative supply via push switches to change direction.  I wired the drive
motors directly to the miniboard motor ports, and re-wired the batteries into
a single 6-volt configuration.  The previous approach used a common ground
for the power reversing, so all I did was pull each motor off of the common
ground, and route that previously grounded lead to the miniboard (paired with
the power lead that ran to the tether controller).

   I was concerned that driving the 3-volt motors with 6-volts might be too
much for them, but they seem to take the abuse well.

   No feedback systems, or sensors (yet- still under construction), but even
as crude as this is, it makes a nice test-bed for assembly code development.

-John
hysell@kodak.com