RoboBee is a flying, swimming microrobot, unveiled by Harvard engineers at the International Conference on Intelligent Robots and Systems earlier this month. Basically a stick with wings, RoboBee is the first insect-like robot to propel itself smoothly through both air and water. The research could aid in the design of vehicles that are both aerial and aquatic.
It is not the first time that we have seen RoboBee in action, but designing something that can fly and swim presents no small challenge. Flying requires large wings or sails to generate lift. But efficient swimming requires a small surface area, to minimize drag forces slowing the swimmer down.
To get around this trade-off, the Harvard team looked for inspiration in some of nature’s most sophisticated aquatic-aerial movers, puffins.
“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 post-graduate Kevin Chen, who presented the paper. “In both cases, the wing is moving back and forth. The only difference is the speed at which the wing flaps.”
The team applied these principles to their bee. At 120 wing flaps per second, RoboBee can fly. But at nine flaps per second, the wings make a smooth, paddling motion that propels RoboBee gently through water.
Right now, RoboBee’s transition from flying to swimming is a little awkward. The robot simply stops flapping, splashes gracelessly into the water, sinks, and then resumes flapping at a much lower speed.
But RoboBee demonstrates how a single robot can move through both worlds with ease, and the researchers say their design is scalable.
“What is really exciting about this research is that our analysis of flapping-wing locomotion is not limited to insect-scaled vehicles,” said Chen. “This strategy has the potential to be adapted to larger aerial-aquatic robotic designs.”
And how could car-sized flying robo-insects not be a good idea?