BEND IT LIKE ... PAPER
Remember that freaky air-powered boneless robot? Well, the same
group that unleashed that thing on the world (George M. Whitesides' lab
at Harvard) has started to manufacture some beautiful (and superbly
functional) air-powered Origami robotic actuators out of paper and
elastic. These "soft pneumatic actuators" are constructed by combining
paper with a silicone elastomer called Exoflex in a mold and casting the
composite so that they contain internal pneumatic networks. The
process is fast, easy, inexpensive, and repeatable. When the pneumatic
networks are inflated with an external source of air, the elastomer
expands, creating an actuator.
The key to the funky shapes that these actuators can make is to use
paper to constrain the ways in which the elastomer can bend. The
simplest form of this is to just place a piece of paper along one side of
the elastomer such that when it's inflated, it bends the other way.
However, there are lots of creative things that you can do with paper.
The examples in the top photo show pneumatic actuators made of
accordion-folded paper/elastomer composites that have had certain folds
glued together to generate specific shapes when they inflate. The second
photo shows an extension actuator lifting a one kilogram weight ( 2. 2
pounds) which is over 100 times the weight of the actuator itself.
Without the weight on top, an actuator like this can fully deploy at
approximately the speed of sound. The researchers have also tested
structures that can contract, twist, and even act as little lanterns by
controlling the amount of light emitted by an embedded LED through
The last graphic illustrates how it's also possible to embed
electronics in these actuators, suggesting the possibility of creating an
entire robot from little more than paper, silicone, and wiring. You'd need a
pressure source too, but it might be possible to use chemical reactions
to generate gas from relatively small amounts of liquids that could
themselves be stored in flexible containers within the robot.
The advantages of robots constructed with methods like these are
numerous: They're simple to make, flexible, expandable, lightweight, and
cheap enough that you could make a whole bunch of them if you wanted
to. There's a reason that DARPA has a whole program dedicated to soft
robots: They can do all kinds of things (and go all kinds of places) that
rigid robots just can't, and with actuators like these, nothing will be able
to stop them.
GRASP ON QUADROTORS
The GRASP (General Robotics,Automation, Sensing, and
Perception) Lab at the University of Pennsylvania is already famous for
its quadrotor tricks, including bots that can fly through windows and
hula hoops, build structures, and even land on each other. Now, those
big bad quadrotors have been shrunk down into much smaller "nano
quadrotors," and the GRASP Lab has been playing around with lots of
them. One possible advantage of having smaller quadrotors is that you can cram more of them into a given space, allowing you
to perform more complex swarm behaviors. These little beauties are eminently tossable, and it sort of looks like you can just
chuck them like ninja stars and they'll self-right and stabilize themselves. Up to 20 of these things can fly in formation all at
once, and it's very impressive to see them make a series of different 3D shapes.
28 SERVO 04.2012