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Mind / Iron
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by Bryan Bergeron, Editor
PUBLISHER
Larry Lemieux
publisher@servomagazine.com
Size Matters
When Parallax announced their
new 12 VDC motors with
mount, wheels, and position
controller, I couldn’t resist picking up
a kit ($280). Finally, a ‘standard’ drive
system designed for medium-sized
mobile robots from the company
behind the BASIC Stamp and the
Boe-Bot.
The verdict? In short, the kit is
first-class. Not only are the aluminum
components beautifully machined
and professionally finished, but the
two 12 VDC motors are powerful
and the gearing is aggressive —
expect about 150 RPM at 1.5A and
no load. Furthermore, assembly
instructions and example Stamp
source code are straightforward
and easy to follow. It took me
all of 20 minutes for basic
assembly, including mounting
the quadrature encoder
assembly and inflating the
pneumatic tires.
I paired my motor kit with a
pair of the recommended HB- 25
controllers ($50 each) from
Parallax. The controllers are
hefty, with built-in heatsinks and
cooling fans, and at less than three
ounces, add little to the overall
weight of about six pounds for the
pair of motors.
Is the kit perfect for every
robotics application? Of course not —
no general-purpose kit could be. For
example, the pneumatic 6” tires;
while well executed, are overkill for
my needs (an indoor balancing bot
platform) given their relatively small
diameter and inherent stiffness. I
replaced the inner tubes with zero
maintenance foam tubing. It’s a trick
I picked up from working with Traxx
wheels. Want a stiffer, more
supportive ride? Simply use denser
foam inserts in the tires.
Another consideration is ground
clearance for the motor and motor
mount. There’s only about an inch of
clearance from the rectangular motor
mount to the contact surface. This
shouldn’t be a problem if your robot
is going to be working on pavement,
carpet, or even a mowed lawn.
However, if you’re thinking of
running your robot down gravel
roads and rough terrain, you might
want to consider protecting the
ASSOCIATE PUBLISHER/
VP OF SALES/MARKETING
Robin Lemieux
display@servomagazine.com
EDITOR
Bryan Bergeron
techedit-servo@yahoo.com
TECHNICAL EDITOR
Dan Danknick
dan@teamdelta.com
CONTRIBUTING EDITORS
Jeff Eckert Tom Carroll
Gordon McComb David Geer
Dennis Clark R. Steven Rainwater
Fred Eady Kevin Berry
Andrew Alter Dennis Bogden
Sam Coniglio Margaret Toebes
Steven Schmitt David Carrier
James Baker Mike Jeffries
Robert Wilburn Paul Reese
William Smith Camp Peavy
CIRCULATION DIRECTOR
Tracy Kerley
subscribe@servomagazine.com
MARKETING COORDINATOR
WEBSTORE
Brian Kirkpatrick
sales@servomagazine.com
WEB CONTENT
Michael Kaudze
website@servomagazine.com
PRODUCTION/GRAPHICS
Shannon Lemieux
Joe Keungmanivong
ADMINISTRATIVE ASSISTANT
Debbie Stauffacher
Mind/Iron Continued
6 SERVO 10.2008
Copyright 2008 by
T & L Publications, Inc.
All Rights Reserved
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