"Reproduced with permission from POPULAR ELECTRONICS Magazine
Jan 1994 Issue. (C) Copyright Gernsback Publications, Inc."

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THE ROBIX(tm) ROBOT-CONSTRUCTION SET
A Great Learning Tool That's Lots
of Fun to Build and Use

     by Marc Spiwak

LEISURE time is a precious commodity these days.  With the
economy the way it is, most of us -- at least those who have to
work for a living -- barely have enough time to do enough work
to make enough money to pay all the bills.  And that means that
most of us just don't have time to play with "toys."

     However, the Robix(tm) RCS-6 Construction System from
Advanced Design, Inc (1101 East Rudasill Road, Tucson, AZ 85718.
Phone: 520-544-2390, Fax: 520-575-0703) is no toy.  It is a
serious educational tool that also happens to be a lot of fun.

     The RCS-6 robot-construction set lets you build custom
robot arms that you control from a PC.  A pre-assembled
interface unit lets you connect the arms to the PC's printer
port with an ordinary printer cable.  The arms can then be
controlled manually or programmed to perform various tasks under
computer control.  And while the set is simple enough that it
can be used by elementary school kids, it's also sophisticated
enough to hold interest at the university level.

     Although the RCS-6's price of $550 might be a bit steep for
many individuals, no science class or technical college should
be without one.  Students at all levels would probably find the
RCS-6 to be the best class activity of the year.  And for those
parents that can afford it, the RCS-6 is a much better
mind-sculpting investment that a Sega Genesis or Super Nintendo
game system.

WHAT'S IT GOOD FOR? Children's toys -- good ones, anyway -- are
designed to help develop strong minds, and many of them actually
help kids develop career interests.  The same can be said of the
RCS-6, except that the RCS-6 will probably inspire just as many
career changes as it will first-time careers.

     That's not to say that the RCS-6 is too complicated for
kids under a certain age.  There are plenty of children under
the age of five that are more comfortable with computers than
their parents.  Besides, running some simple DOS-based software
and connecting a printer cable is all you have to do on a
computer to use the RCS-6.  The rest of it is similar to playing
with an Erector Set.

     But even though the RCS-6 is educational and fun, it is,
once again, not just a toy.  It can be a productive and useful
tool, and is, in fact used in industry.  For example, a General
Electric R&D lab uses an RCS-6 robot to handle test tubes for
feeding a gas chromatograph.  The RCS-6 is actually a quick,
simple, and relatively inexpensive way to add robotic
capabilities to many light-duty industrial applications.  That's
because custom-made single-purpose robots can be prohibitively
expensive.

WHAT YOU GET.  The RCS-6 comes with two different mounting
bases, various sized anodized aluminum brackets, different types
of clamps, and many accessories.  Even the few required tools --
a small Phillips screwdriver and an allen wrench -- are
supplied.  There's even a pair of goggles to guard against the
remote possibility of eye injury during construction.  To round
things out, the set comes housed in a rugged tackle box that
provides easy access to everything.

     The computer-interface is small in size and rests on the
robot arm base.  It turns command from your computer into
control signals for the six servos.  The interface also has two
on/off outputs that can supply 150 milliamps of drive current
for LED's, relays, solenoids, or whatever.  Also included are 0-
to 5-volt analog sensor inputs and an 8-bit A/D converter as
well as simple on/off switch-closure inputs.  While an AC
adapter for the interface is included, you do have to supply
your own printer cable to connect the interface to your
computer.  However, you probably already have the printer cable
if you already have the required PC.

     Which brings us to the computer.  Although you need a
computer to control the RCS-6, a lowly 4.77 MHz PC is all the
computer power you'll need.  If you don't already have an old PC
clone, and can't find one that somewhat has put out for the
garbage men, you can certainly purchase one for much less that
the price of the RCS-6.

     The RCS-6 comes with enough parts to make all different
kinds of arms -- though not all at once -- with up to six
motorized joints, or elbows.  The motors are actually Futaba
S148 hobby servos, which can be readily replaced if the need
ever arises.  The servos provide a good degree of precision to
any arm movement, although they can get the "shakes" when they
try to maintain a steady position under load.

     Quite often people are hesitant in using anything that
connects to a computer, and on top of that the RCS-6 can seem
intimidating at first simply because of all the parts included
in the set.  Fortunately, a VHS videotape that is supplied along
with the instruction manual dissolves all fears one might have
of using the set.  Although you can start right out and build
the robot arm of your dreams, it's best to start off by watching
the video or following along with it, and build the example arm
shown.  It's a good way to familiarize yourself with the parts
and how they're used.  And they are very easy to use.  Using the
software is also explained in the video, and it turns out that
the software, too, is simple to use.

BUILDING AN ARM.  When you set out to build an arm, you have to
consider where you want to have movement and what sort of
movement you want.  You basically get to decide where you want
the shoulders, elbows, wrist, and gripper.  We built the arm
demonstrated in the video, which makes use of all six servos.
Aside from a few starts and stops, we were able to keep up with
the assembly pace of the demonstration video and had our arm
assembled in about an hour.

     An important part of the assembly procedure is to properly
dress the servo wires so that none will be damaged by pinching
or bind the arm's motion.  Foam-rubber blocks and spiral wire
wraps are included to help secure the wires.  The servos are
numbered 1 through 6 according to their position moving outward
from the base.  Their leads are connected to the interface
outputs by a trial-and-error process.  Connecting a servo lead
to any output on a live interface will make that servo come to
life.  Then its number can be noted and its lead plugged into
the proper output.

SOFTWARE CONTROL.  The software comes on a single floppy disk,
and both 3 1/2- and 5 1/4-inch disks are included.  A
customizable batch file sets up the software to run on your
machine and loads the driver.  The software is relatively easy
to use, and Windows-like in appearance.

     Various software consoles and menus let you control the arm
from either the keyboard or the mouse.  On the keyboard, keys
1-6 move servos 1-6 in one direction, and the keys below them
("qwerty") move the servos in the opposite direction.  The two
rows of six keys below those control the servos with much slower
movement for more delicate maneuvers.  Keys can be pressed
individually or in combinations.

     Any movement or combination of movements can be stored.
The motion can then be repeated with a keystroke or mouse click.
A motion sequence can also be stored as a macro that can be used
to control the arm under higher-level software so that a PC can
control an entire system incorporating a Robix arm to do some
tasks.  Also included are C and QuickBASIC libraries to run your
robots.

IS IT WORTH IT?  We had a lot of fun building just one robot
with the Robix RCS-6, and we barely scratched the surface.
Surely, if you are interested in robotics you should do whatever
you have to do to get your hands on one of these arms; it is a
must-have learning tool.  Even better, it is one that could be
put to useful work as in the GE lab mentioned earlier.

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