Mind / Iron
by Bryan Bergeron, Editor ;
Re-inventing the Wheel
The field of robotics is so vast – spanning
mechanical, electrical, and computer engineering –
that you have to focus on one area to get anything
done. For example, if you’re into pattern
recognition-based navigation, you’ll have your
hands full with image processing algorithms and
perhaps image acquisition hardware design.
That said, it pays to occasionally broaden your
focus and take a look at what’s happening outside
the world of robotics. There’s a lot of activity in the
electronics industry that can be applied directly to
robotics, saving you time and money.
For example, I was looking for a way to quickly
illuminate a scene with IR, alternating with visible
light in order to improve a vision-based navigation
system. I started with two banks of LEDs and an
6 SERVO 11.2011
Arduino Mega processor. However, a few weeks
later — while searching for LEDs on eBay — I
happened across several inexpensive LED light
arrays, all compatible with DMX512 controllers. Up
to that point, I hadn’t heard of DXM.
It turns out that the DXM (Digital Multiplex)
standard has been around for decades, and that it’s
used to control dimmers, fog machines, and
moving lights. You can check out the standard on
the Web, but the point is that I was just about to
replicate a small part of the DXM standard,
unaware that I could buy — off the shelf — exactly
what I needed. Compact controllers with an
assortment of sliding and rotating potentiometers
and buttons are readily available.
More importantly, for my project I located an
inexpensive Arduino-compatible DXM board. The
microcontroller board enables me to control the IR
and visible LED banks through a USB link with my
laptop, as well as run the banks autonomously.
Are you in the process of unknowingly re-inventing a protocol or algorithm that’s been
around for years? There’s something to be said for
what can be learned by tackling a tough software
or hardware problem. The problem is that time is
limited, and you’re probably better off buying
infrastructure devices and focusing on your
strengths and interests.
Also, when you’re trying to solve a problem,
the solution isn’t always selling on eBay or Amazon
for a few dollars. It may be the problem and
resulting solution were addressed in the past, with
little or no commercial footprint. Take the
hemispherical omnidirectional gimbaled wheel, or
HOG wheel. It’s been around for nearly a century,
but unless you follow RoboGames you probably
don’t know how it works, or how you can apply it
to robotics.
According to IEEE Spectrum (spectrum.
iee.org/blog/automation) Curtis Boirum, a
graduate student at Bradley University
demonstrated a drive system based on the HOG
wheel at the 2011 RoboGames symposium. The
drive is a rubber hemisphere that rotates about the
vertical axis, with servos that can tilt the axis left
and right and forward and backwards. You can see
two versions of the robot in action by searching for
“Hemispherical Gimbaled Wheel Drive System” on
