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Our objective is to design self-
assembling and self-reconfiguring
robot systems. These are modular
robots with the ability of
changing their geometry according
to a task. And this is exciting
because a robot designed for a
single task has a fixed
architecture and that robot will
perform the single task well but
it will perform poorly on a
different task in a different
environment. If we do not know
ahead of time what the robot
will have to do and when it will
have to to it, it is better to
consider making modular robots
that can attain whatever shape
that is needed for the manip-
ulation, navigation or sensing
needs of the task. Up until now
most other modular robotic
systems use servos and motors
in order to have arms that and
attachments that move modules to
different places. However we
wanted a simpler approach that
uses fewer actuators, fewer
moving parts and was easier to
implement on a lot of different
robots. So the approach we chose
to use is angular momentum.
And essentially what that means
is there is a spinning mass that
spins inside the robot. If we
want that robot to move it stops
that spinning mass which takes
that motion from the mass and
applies it to the robot. And the
part of this that is unique is
that the spinning mass is
completely inside the robot and
so the robot doesn't have to be
in a certain position in order
for the force to be acted upon
the robot so this allows for
a lot more types of motion with
only one actuator.
So there were a couple challenges
when we came to design the
m-blocks, one, was fitting
everything inside. So we have a
relative small volume and we
needed to fit a brushless motor
controller, a flywheel, a
breaking mechanism, electronics
a radio and a battery.
Additionally we faced the
challenge of trying to simplify
and try and make the design as
robust as possible. So we didn't
want any external moving parts.
We didn't want latches, we
didn't want the cubes to change
their shape. We just wanted
simple blocks that were able to
move on their own. The magnet
system in the cubes is one of
its key features. We have face
magnets. There's eight face
magnets that provide some course
alignment and then there are
these edge magnets which are
free to rotate. And the key is
that when a cube starts rotating
the edge magnets actually get
close to one another. So if we
start from this configuration and
we break the face magnets free
and start rotating the edge
magnets actually get a little
bit closer due the fact that the
edge is slightly cut back and as
a result you form a very strong
bond between cubes which allows
them to stay attached as one is
rotating into a new position. It
continues rotating, the face
magnets provide alignment and
it snaps into place.
One other benefit of having an
internal actuator is that the
cubes are able to jump
and this is a capability that
very few robots have. Especially
very few modular robots because
in order to jump there's a
requirement for a very high
amount of energy in a very short
amount of time and most robots
are optimized for control,
stability and precise motion.
In our robot we found it kind of
as an accident that they are
able to jump, we weren't
intending to do that but it ends
up that we need enough momentum
inside each cube in order to
move on a lattice structure,
which is what we intended, that
we can also, when we apply as
much energy as possible, it can
jump through the air which is
pretty exciting because it also
allows robots to jump on top
of each other and go places that
they couldn't go if they were
only moving directly on the
structure. Currently we're
sending commands to the modules
with a radio. So we type commands
on our computer, those are
transferred over a wireless link
like your wifi system in your
house, and then the cube responds
to that. In the future we
envision putting the algorithms
on the modules themselves so
they can completely, autonomously
in a distributive fashion decide
how, when and where to move. So
we want to be able to take a
large group of cubes and tell
them form this shape, and give
those instructions at a very high
level and then have the cubes
decide, on their own, how to go
about accomplishing that task.