PERSONALROBOTICS
UNDERSTANDING, DESIGNING & CONSTRUCTING ROBOTS & ROBOTIC SYSTEMS
■ BY PHIL DAVIS
PARAMETERS ON THE FLY: Part 3
THIS MONTH, I WOULD LIKE TO WRAP UP the design and functioning of the
Hand-Held Console by showing you the completed device and by posting the
software online for all to use.
The idea behind this device is
to allow the changing of those
variables which are typically used to
tune or control the robot. For example,
if you have a robot that is designed to
stop four inches from a wall, then you
will probably have a distance sensor
and a variable containing 4 and the bot
will stop when the distance sensor
matches the variable. However, when
building your robot you find that due
to inaccuracies in the distance sensor,
your robot actually stops six inches
from the wall. Typically, the only way to
fix this is to edit your code, recompile
the program, and download in into the
robot. You might find you have to do
this many times to get it just right. With
the Hand-Held Console we are building, you will be able to do this on-the-fly, without having to change the code.
PHYSICAL LAYOUT
In the previous articles, I talked
about most of the components which
go together to build this device. The
first of these is, of course, the frame
which is made out of ‘white board’
and cut on a laser printer. As you can
see in Photo 1, there is a hole cut
for the LCD, a small slot just beneath
that for the keypad cable, and a
series of holes for your fingers to get a
good grip.
In Photo 2, you can see the
front of the console with the LCD
installed and the keypad ‘stuck’ onto
the surface. This particular keypad
comes with a self-adhesive back; just
peel off the cover and press in place.
It also has a ribbon cable which plugs
directly into the LCD and can
then be read off the I2C from the
processor board — very simple
and easy. Also note on the top left
the on/off switch and the two
momentary switches for controlling
the functions. Sticking up from the
back at the top is the rubber duck
antenna from the A7 Engineering’s
■ PHOTO 1. White board cut out.
EB501 Bluetooth device.
You may have noticed that the
console is no longer white. Jerry —
who cuts the white board on his
laser (see the Resources sidebar
if you need something or this
console cut) — decided to spray
paint it silver. The paint had some
strange reaction with the white board
— probably an oil layer — and formed
an odd textured pattern. I liked it, so
I kept it.
Looking at the console from the
back in Photo 3, you can see how that
various components are arranged. The
LCD is secured in place via screws
through the laser cut holes, however,
the rest of the components are held in
place with double-sided tape. There is
no real stress on these components
and it saves putting holes through the
white board, especially where the
keypad is. The LiPol Battery is held in
place with Velcro®, allowing removal
for charging.
Photo 4 is a quick shot of the
console being held with
both hands just to test the
usability and position of
the components. Seems
to work very well!
I have been using
two different Bluetooth
modules for this project.
One is the “Embedded
Blue” product offered
by Parallax and the other
is the EB501 offered
by A7 Engineering. The
EB501 is a good fit
■ PHOTO 2. Console front
with components installed.
12
May 2007
