Sorry MIT, but you’re not the only university in Massachusetts bringing sci-fi technology to reality. Recently, researchers from Harvard’s microrobotics lab showed off the world’s first insect-sized robot that can not only fly, but swim.
Dubbed the ‘RoboBee’, the miniature device is smaller than a paperclip and is just as adept at flying through the air as it is at maneuvering through water. When in flight, the device maneuvers by flapping its wings upwards of 120 times per second. When underwater, the device is able to maneuver by slowing its flap rate down and changing the angle of its wings to adjust direction.
Of course, creating a dual-purpose device was not without its challenges. In order to get the tiny sized robot to work properly, Harvard researchers had to develop a solution wherein the aerodynamic properties of the RoboBee wouldn’t impede the device’s ability to maneuver through water.
“The biggest challenge is conflicting design requirements,” Leah Burrows writes on Harvard’s website. “Aerial vehicles require large airfoils like wings or sails to generate lift while underwater vehicles need to minimize surface area to reduce drag.”
Interestingly enough, Harvard engineers were able to solve the problem by taking a cue from puffins, a species of bird with notoriously color saturated beaks.
The birds with flamboyant beaks are one of nature’s most adept hybrid vehicles, employing similar flapping motions to propel themselves through air as through water.
“Through various theoretical, computational and experimental studies, we found that the mechanics of flapping propulsion are actually very similar in air and in water,” said Kevin Chen, a graduate student in the Harvard Microrobotics Lab at SEAS.
“In both cases, the wing is moving back and forth. The only difference is the speed at which the wing flaps.
Another challenge the Harvard team had to overcome was getting the RoboBee into water in the first place.
In order to make the transition from air to water, the team first had to solve the problem of surface tension. The RoboBee is so small and lightweight that it cannot break the surface tension of the water. To overcome this hurdle, the RoboBee hovers over the water at an angle, momentarily switches off its wings, and crashes unceremoniously into the water in order to sink.
Once underwater, the team had to account for the fact that water is much denser than air. As a result, the RoboBee’s wings, upon submersion, only flap at about 9 times per second, thereby prevents the miniaturized device’s wings from being snapped off underwater.
“A swimming RoboBee changes its direction by adjusting the stroke angle of the wings, the same way it does in air,” Burrows explains. “Like a flying version, it is still tethered to a power source. The team prevented the RoboBee from shorting by using deionized water and coating the electrical connections with glue.”
Thus far, the RoboBee can successfully transition from the air to the water, but not in the opposite direction. Looking ahead, designing a RoboBee capable of generating enough lift out of the water without damaging the wings is the next design hurdle the team will be hoping to solve.
As for practical applications, Harvard’s RoboBee project has its own dedicated website with a mission statement of sorts:
INSPIRED by the biology of a bee and the insect’s hive behavior …
we aim to push advances in miniature robotics and the design of compact high-energy power sources; spur innovations in ultra-low-power computing and electronic “smart” sensors; and refine coordination algorithms to manage multiple, independent machines.
Coordinated agile robotic insects can be used for a variety of purposes including:
- autonomously pollinating a field of crops;
- search and rescue (e.g., in the aftermath of a natural disaster);
- hazardous environment exploration;
- military surveillance;
- high resolution weather and climate mapping; and
- traffic monitoring.
These are the ubiquitous applications typically invoked in the development of autonomous robots. However, in mimicking the physical and behavioral robustness of insect groups by coordinating large numbers of small, agile robots, we will be able to accomplish such tasks faster, more reliably, and more efficiently.
Interestingly enough, Harvard isn’t the only institution looking to develop a hybrid device capable of flying and swimming. As we’ve highlighted previously, the United States Naval Research Laboratory has also been hard at work trying to develop a drone that can fly through the air and swim underwater.