and a weapons system. Being a long time fan
of the Battletech series, I wanted to model
my own Mech after one of my favorites
from the franchise, the Vulture. While
aesthetically pleasing, the design of
this fictional Mech is very impractical
in the real world. Its theoretical
walking gait, extreme reverse leg
design, and disproportional leg
to torso size ensure that this
Mech will continue to reside
only in the sci-fi universe. I
was determined to capture
some of the look and feel of
the Vulture while adapting it
to a more practical real
world design. Figure 1 is the
3D model captured from the
videogame Mechwarrior 4™
that I used as inspiration for
my design.
To prototype my design, I chose the
Bioloid Comprehensive Kit from Robotis
( www.robotis.com). I give this kit
my highest recommendation.
The modular bracket
building system,
impressive AX- 12 servos,
and the simple ‘pose
and capture’ software is
a dream come true for
rapid prototyping. I
built the stock
Bioloid humanoid
to get a feel for
how the system went
together and upon doing
so I noticed that the
humanoid’s legs turning
around backwards made
a nice reverse knee
design. (Refer to
Figure 2 for reference.)
I figured this would
be a simple starting point as the
walking gait would be the same as that
of the stock humanoid, so I decided to
do some further testing. Almost
immediately, I noticed that keeping the knees
slightly bent backwards would cause more strain
on the weight-supporting servos. Checking the
temperatures only confirmed this and simple
physics explains it; just try walking around with your legs
bent at a 90 degree angle at the knees. Bipedal robots
are more efficient when the servos are aligned vertically
so that load-bearing servos hold most of the payload on
top of their rotational shaft, rather than at a point of
leverage. To stick with the Vulture’s overall aesthetics,
Figure 2
I needed to stray away from a
standard humanoid leg
configuration, so I started
looking at different options.
My good friend Jon Hylands
is a researcher with the Brain
Engineering Lab at Dartmouth
College, and has done some
impressive work towards alternate
walking gaits for bipedal robots
using his Bioloid based MicroRaptor
robot (shown in Figure 3). He
implemented a seven degree of
freedom leg design based on a
Velociraptor and with that,
started work on different types
of walking gaits than what is
normally seen with bipedal
robots. Here are Jon’s
thoughts behind the gait
he is using:
Figure 3
“Most bipedal robots
today walk using a
strange technique that
involves keeping each
foot more or less
aligned horizontally
with the corresponding
hip. If you try and
walk that way, you
end up looking like
these robots, with
your upper body
swaying back and
forth as you
desperately try
and keep your
balance. Clearly,
we’ve got
a long
way to
go to
get realistic
walking. One of
the techniques I’m planning on trying
with MicroRaptor is to use longer strides,
with the legs coming under the body to
maintain balance without rocking the entire
upper body back and forth.”
By using Jon’s MicroRaptor leg design,
I moved away from the standard humanoid
approach while gaining upper torso stability
(which would prove to be critical for aiming
while piloting remotely). While this leg design
differs from that of the Vulture, it proved to be
much more functional while still maintaining a
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