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returns to the charge base
and resumes where it left off.
It offers easy scheduling of
daily cleaning or a button for
instant cleaning. The versatile
brush system offers superior
pick-up of pet hair, dander,
and fiber on all floor types.
The special filters retain more
than three times the amount
of fine dust particles as
standard filters, which is
perfect for removing
allergens from the home.”
Per formance
Evaluations
I’ve had my Roomba 560
(shown in Figure 4) for five
years now. It was given to me
by Helen Greiner (Chairman
of the Board of iRobot at the
time) to test and evaluate.
This was just before she left
the company in October 2008
to start her own company,
CyPhy Works. Helen has
degrees in Mechanical
Engineering and Computer Science
from MIT, and she was a most
interesting technical conversationalist.
We talked at length about military
robotics, her main interest at iRobot,
and robotics to assist the elderly in
independent living — a particular
interest of mine. With her technical
and business acumen, I know her
magic touch will continue to help her
own company succeed.
Roomba 560 Testing
Back in the day, almost
immediately, I began to have trouble
with the Roomba 560, so I contacted
Helen about it. She put me in touch
with several of her technical people to
discuss the problems. The Roomba
would operate quite fine for a half
hour or so, and then would stop and
tell me “Please clean Roomba’s
brushes.” I checked them and found
only a tiny bit of dirty fuzz, pulled out
some hair near the bearings, and
returned it to cleaning. The “clean
me” message came again too quickly.
Hmmm. What was making the
machine think the brushes weren’t
clean? Something must be causing a
higher current draw on the motor.
I pulled off the yellow plastic-capped bronze bushings (Figure 5)
and saw two types of hair bound on
the brushes. You can see the bearing
containing a bronze bushing on the
right of the bristled brush and the left
of the rubber brush. The fluffy hair
was easily removed with a pair of
tweezers and an XActo™ knife.
However, there remained a tiny cone
of hair tightly fused on the steel shaft.
This cone had been burnished by the
bronze bushing’s friction and melted
into a solid mass.
It appeared that this cone was
slowly building up like frozen ice and
was pushing the bushing up the brush
shaft that was then shoved into the
gearbox, damaging it. Hair was the
culprit, and just a tiny amount! Other
Roomba owners posted on the
Internet that hair often entered into
the gearbox through cracks
caused by distortion of the
case, jamming the gear train.
I placed two digital
voltmeters on the battery
supply: one in series for a
current measurement and
one in parallel to read the
battery voltage. After carving
away the ‘hair cone,’ I started
up the Roomba. After a half
hour, sure enough, the
current started to rise, the
voltage dropped, and, lo and
behold, Roomba soon cried
out again to “clean my
brushes.” A few slices with
my XActo knife and it was
working again.
I called iRobot and
attempted to get in touch
with engineering personnel
as I had heard they had many
returns due to damaged
gearboxes. It was not until
last year that I finally saw
they had changed the
bearings and end caps to
remedy this problem. Figure
6 shows the new green brush end rim
that encloses the problematic bearing
assembly. I never saw suggestions
printed in their literature or on their
website about the ‘hair cone’ buildup,
but the new brush end design seemed
to have eliminated this issue.
Despite the hair problem and
shorter battery life than I expected, I
was and still am impressed with the
Roomba 560. Using an entirely
different approach and algorithms for
the cleaning process, the 560 does a
good job cleaning my carpets. Many
reviewers have tested robot vacuum
cleaners by sprinkling Cheerios,
sawdust, and even flour on hardwood
and carpeted floors to test how fast
and thoroughly the debris is removed.
Normally, these types of spills are
picked up with a broom and dustpan.
The robot vacuum cleaner is at its
best when picking up random debris. I
have found that Roomba does a good
job picking up the typical debris like
grass pieces, dirt, and sand particles
(and that ‘fluff’ that looks like dryer
Figure 4. iRobot Roomba 560.
Figure 5. Two different Roomba brushes with hair buildup.
