TEAR DOWN
The iRobot Looj
by Bryan Bergeron
The treaded, weatherproof, remotely
controlled Looj from iRobot is intended
to facilitate the dull, dirty, and often
dangerous job of clearing gutters of leaves,
pine cones, twigs, and other light debris. At
$99, I couldn’t resist exploring the potential of
the Looj as a robotics platform. Following is a
tear down of the Looj and wireless controller.
SPECIFICATIONS
The Looj is an elongated tank geared for power, as
opposed to speed. Unlike most inexpensive robotics
platforms, the Looj is weather-resistant. You can run it
through a wet gutter or puddle and then hose it off.
The motors, electronics, and removable 7.1V NiCad battery
pack are sealed from the environment. On the downside,
turning is out of the question. Movement is limited to
linear forward and reverse and the powerful front auger
doesn’t seem obviously useful for tasks other than
clearing or drilling a path. Given these caveats, the Looj
has definite potential.
The basic specifications of the Looj, based on my
measurements, are summarized in Table 1. A third of the
total unit weight of about three pounds is due to the
battery. Despite the weight, the robot moves at a
respectable nine inches per second. It isn’t a stealth
28 SERVO 05.2008
platform, but sounds like a power drill when either the
auger or drive motor is engaged. Current drain — 300 ma
with drive activated and an additional 500 ma for the auger
— was measured with a bench power supply set to 7.1V,
connected to the Looj using a hand-held cord with the
battery pack installed in the compartment. Radio control
range — a very modest 57 feet — was measured with the
Looj in an empty parking lot with the controller held at
waist height. The indoor range test was conducted with
the robot and controller separated by a sheetrock wall.
Unfortunately, charging the battery involves removing
the water-tight compartment lid (two screws), removing
the battery pack, and connecting it to the micro-sized wall
charger. Given the ‘dumb’ charger provides only 150 mA,
charging the NiCad pack requires 15 hours, and the charger
doesn’t have an auto-shutoff feature.
CONSTRUCTION
Not obvious from the specifications is the ruggedness
of the Looj. This isn’t a typical carpet roamer robot. I didn’t
attempt it, but I’m convinced that it would survive a fall
from roof height onto a grassy surface. In addition —
although I didn’t measure the torque of the auger tip or
drive — I couldn’t stop the auger tip or the rear wheels
with my bare hands. Think cordless power drill for both
the auger tip and the drive mechanism.
In other words, while this power may be a boon to
your development plans, small fingers should not be
