Mini-robots modeled on insects may be smallest, lightest, fastest ever developed
Washington State University
Such miniature robots could someday be used
for work in areas such as artificial pollination, search and rescue,
environmental monitoring, micro-fabrication or robotic-assisted surgery.
Reporting on their work in the proceedings
of the IEEE Robotics and Automation Society's International Conference on
Intelligent Robots and Systems, the mini-bug weighs in at eight milligrams
while the water strider weighs 55 milligrams.
Both can move at about six millimeters a
second.
"That is fast compared to other micro-robots at this scale although it still lags behind their biological relatives," said Conor Trygstad, a PhD student in the School of Mechanical and Materials Engineering and lead author on the work.
An ant typically weighs up to five
milligrams and can move at almost a meter per second.
The key to the tiny robots is their tiny
actuators that make the robots move.
Trygstad used a new fabrication technique
to miniaturize the actuator down to less than a milligram, the smallest ever
known to have been made.
"The actuators are the smallest and
fastest ever developed for micro-robotics," said Néstor O.
Pérez-Arancibia, Flaherty Associate Professor in Engineering at WSU's School of
Mechanical and Materials Engineering who led the project.
The actuator uses a material called a shape
memory alloy that is able to change shapes when it's heated.
It is called 'shape memory' because it
remembers and then returns to its original shape.
Unlike a typical motor that would move a
robot, these alloys don't have any moving parts or spinning components.
"They're very mechanically
sound," said Trygstad. "The development of the very lightweight
actuator opens up new realms in micro-robotics."
Shape memory alloys are not generally used
for large-scale robotic movement because they are too slow.
In the case of the WSU robots, however, the
actuators are made of two tiny shape memory alloy wires that are 1/1000 of an
inch in diameter.
With a small amount of current, the wires
can be heated up and cooled easily, allowing the robots to flap their fins or
move their feet at up to 40 times per second.
In preliminary tests, the actuator was also
able to lift more than 150 times its own weight.
Compared to other technologies used to make
robots move, the SMA technology also requires only a very small amount of
electricity or heat to make them move.
"The SMA system requires a lot less
sophisticated systems to power them," said Trygstad.
Trygstad, an avid fly fisherman, has long
observed water striders and would like to further study their movements.
While the WSU water strider robot does a
flat flapping motion to move itself, the natural insect does a more efficient
rowing motion with its legs, which is one of the reasons that the real thing
can move much faster.
The researchers would like to copy another insect and develop a water strider-type robot that can move across the top of the water surface as well as just under it. They are also working to use tiny batteries or catalytic combustion to make their robots fully autonomous and untethered from a power supply.