Tune in each month for a heads-up on
where to get all of your “robotics
resources” for the best prices!
Building a Robot?
Don't Forget LEGO!
Tabout 2001 and you'll see
thousands of eBay sales,
ake the Wayback Machine to
hundreds of websites, and dozens of
books on LEGO robotics. While the
giddy heyday of the LEGO robot has
come and gone, it's still a viable — and
fun! — platform for learning all about
desktop automatronics.
What's more, publishers keep
coming out with new and improved
books on the subject, and the websites
devoted to robotics and LEGO continue
to be an active, if not mature, community
of like-minded enthusiasts.
In this month's column, we'll look
at the current state-of-the-art in LEGO
robotics — why you might want to
consider using a "toy" to construct
your next automaton, what you need
to get started, and where to find
some great deals.
At the Core: The
Mindstorms Controller
There are many different ways to
construct a robot using LEGO parts.
One is to merely cobble together the
bricks, plates, beams, and other
common LEGO components and
combine it with some gear or servo
motor you found in your junk bin.
Add a BASIC Stamp or some other
microcontroller board, mix in some
batteries, and there's your bot.
For the purposes of this column,
I'm talking about LEGO robots built
around the LEGO Mindstorms
controller: an electronic device that is
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sold as part of the LEGO Mindstorms
set. The set is available for purchase at
many toy stores, electronics outlets,
Amazon, and other online retailers.
There have been several iterations
of LEGO Mindstorms since its
introduction 10 years ago. The
first was the ubiquitous yellow
programmable "brick" controller
known as the RCX. The RCX was part
of a now-discontinued product — the
LEGO Mindstorms Robotics Invention
System (or RIS). Today, LEGO sells a
second generation package called the
LEGO Mindstorms NXT. This kit of parts
sports an updated programmable brick
(the NXT). The basic idea behind the
NXT brick and its older RCX brother is
the same: Create a program on your
PC, download it to the brick, then hit
the Run button. The controller plays
your program and operates your
robot. Both the RCX and NXT connect
to motors to move the robot around
and sensors to detect the machine's
immediate environment. The sensors
in the NXT package are more
sophisticated and varied than those
that shipped with the earlier RIS, but
you can make perfectly functional
bots with either Mindstorms version.
As noted above, you develop
your Mindstorms programs on your
personal computer. Once created,
your program must be compiled and
transferred to the Mindstorms brick.
On the RCX, this was accomplished
using an infrared "tower." The first
RCX units came with a tower that
required a serial connection to the
host PC. Later versions worked with a
USB connection, making them more
universal with the latest computers,
which lack the nine-pin serial
connection common in PCs of the
80s and 90s. The NXT eschews the
infrared tower and works with a USB
cable that connects the computer to
the brick. Though the RCX is no
longer made, it's worthy of mention
because it's still available for resale on
sites such as eBay, and usually at
considerable savings. You can often
find the RCX brick sold by itself for
under $40 and complete Robotics
Invention System packages (including
the RCX) for less than $100. List price
for a new Mindstorms NXT is $199.
Motors and Sensors
and Other Goodies
While a robot is not absolutely
required to be mobile or even have
moving parts, the LEGO Mindstorms is
set up for building rolling machines. Both
the RCX and NXT controllers support
up to three motors. Two are included
with the older RCX-based sets; three
come with the NXT. You can buy
more if you need them. The motors
for the NXT are more sophisticated
and incorporate rotation sensors to
determine distance of motion (rotation
sensors are extra for RCX-based robots
and are not part of the RCX motors).
Sensors make the robot, and this
applies to LEGO Mindstorms as well.
The sensors packed with RCX kits were
rudimentary: just touch (contact
