Many of the earliest
home-built robots that I
saw years ago were
made with wood or
Wheels were mostly from
a child’s riding toy —
especially the surplus
motorized wheels that
used a Mabuchi RS85
6 VDC motor that were
popular in the 1980s.
Large pots and pans
as well as small trash
cans made great robot
bodies — and still do.
Back in the ‘80s, there
was a company who
made a robot they named Garcan ...
you can guess what they used for the
body. 6061-T6 aluminum sheet stock
and angle extrusions are the structural
members of choice for today’s home-built robots.
Kid’s riding toys still make great
robot platforms, as does virtually any
other item you personally feel will
make a great component. The ‘big
box’ hardware stores as well as the
small neighborhood stores are always
great parts places. Goodwill stores,
surplus stores, used appliances,
plumbing, drapery hardware, cabinet
fixtures, auto supply stores, and, of
course, electronic parts stores are
always a ready source of robot parts.
However, these places have always
been around. It is the availability of
those items that I mentioned in the
second paragraph that have caused
the tremendous popularity in home-built robotics. These components were
not always available to the amateur
robot builder just a few years ago.
I’d like to discuss batteries, as
improvements in this technology have
allowed some amazing robots to be
built. Batteries have long been the
Achilles heel of robot design —
especially humanoid robots. Robots
tend to require more power than any
of today’s batteries can supply.
The smallest robots can use
primary alkaline AA or even AAA
batteries, though rechargeable AA
cells save experimenters a lot of
money in the long run.
Newer types of secondary
(rechargeable) batteries have been
responsible for some of the most
notable improvements in robot
operation — especially the flying
robots. A quick look at Honda’s
humanoid robot, Asimo will illustrate
how battery technology evolved to
accommodate the robot’s technical
advances through successive models.
Figure 4 shows Asimo backed up
against its charger while its latest
51. 8 volt lithium-ion battery is being
charged. Though the battery
resembles a backpack, it is really an
extension of the robot’s backside from
its bottom to shoulders. There was no
way that Honda engineers could have
placed an adequate battery within the
Prior to the lithium-ion battery,
Asimo operated from a nickel metal
hydride battery of 38. 4 volts that
lasted for 30 minutes of operation and
weighed almost 17 pounds. The
newer li-ion battery weighs
only a bit over 13 pounds
and lasts for a full hour of
walking or running.
batteries (or NiCads, as
they are frequently called)
were used quite a bit in
smaller robots and have
been available for general
use since the ‘60s. At
1.2 volts per cell, 10 cells
made a 12 volt battery pack. They are
rechargeable but have a major
negative aspect of retaining a
‘memory effect’ when they are
partially discharged and then
recharged — a trait that caused them
to lose popularity with robot builders.
Popular cell sizes are AA and sub
C. The sub C size versions were
frequently used in battery packs for
portable power tools, camcorders, and
similar portable devices.
Lead-acid batteries have been
used in cars and many other
applications since the turn of the
century and before, but they were
mostly the liquid sulfuric acid
electrolyte types that could easily spill
the acid. In the ‘80s, gelled electrolyte
lead-acid batteries were the mainstay
for larger robots — those of 30 pounds
or more. They were fairly safe as they
could be inverted without leakage, but
a cracked case usually resulted in
sulfuric acid gel leaking all over the
robot or whatever was under it.
They can be used in robots today
but should be carefully handled and
not dropped. At a bit over 2.0 volts
per cell, a 12 volt battery consists of
six cells. The UB1280 sealed lead-acid
battery shown in Figure 5 is still a
very popular battery for mid-sized
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Advances in robots and robotics over the years.
SERVO 10.2014 77
Figure 4. Honda's Asimo humanoid
charging its battery.
Figure 3. A micro-SD
contains 64 billion