The Bee & The Perfect Landing

2 October 2014

 “Bee” by Ewok Jorduman

            Bee populations throughout the world, and particularly in the United States and Europe, are dropping rapidly and mysteriously.  The fate of bees, generally, is a matter of concern these days.  But why are bees so important? 

            Agricultural production.  Without the bees’ unique service as pollinators, the value of yearly agriculture output would drop by billions of dollars.  But dollars aren’t the worst part of the problem. 

            Agricultural production is food.  Without bees, we would have less food than we need to feed the Earth’s population.  So, without bees, a substantial number of people on earth will begin to starve – quickly. 

            But beyond their important place in the food chain, bees seem to continue to attract even more interest. This insect’s amazing sense of smell, much more acute than a dog’s, has already lead to technologies that allow bees to be used to sniff out drugs at airports and, even, detect diseases in human beings.

            And, then, DARPA became interested in bees.  DARPA?  Yes, the Defense Advanced Research Projects Agency of the United States Department of Defense.

           Why? 

            Drones.  Not the bee kind of drone – a male bee — but a mechanical a drone.  More precisely, flying drones.  DARPA is trying to build a drone that is about size of a bee.  Small objects can go where large objects can’t.  The applications are obvious.  An insect-sized drone would be invaluable not just in surveillance and reconnaissance but, also, in search and rescue. 

            But couldn’t DARPA model its mini-drones after another insect?  In other words, when it comes to designing flying drones, what’s so special about bees?  The special thing about bees is that, among their fellow insects, they are the virtuosos of flight.  Bees can fly faster than most other insects.  Also, they can fly slower (hover) in a way that most other insects cannot.  In flight, bees maneuver with a precision almost unparalleled in the insect world.  If you were DARPA and wanted to develop an insect-sized flying drone, you’d want its capabilities to be as close to those of a bee as possible.

            Harvard’s “Micro Air Vehicles Project” is working on the developing a robot that is intended to duplicate the functions of a honeybee.  This robot became a sensation when it was announced that Robo-Bee could fly.  But the word “fly” was, and is, used in the most restricted and technical sense. 

            For most of the last few years, Robo-Bee has been able to flap its wings, and rise into the air – “fly.”  However, when it does, it shoots from its starting position across the room and crashes into the nearest wall.  Flight over.  Total flight time – about a second.

            But now researchers have figured out how to guide Robo-Bee in flight.  Now, with the latest guidance breakthrough, the robo-bee can be made “to pitch and roll in a predetermined direction” and, then, . . . it crashes into the nearest wall.

            While researchers are working on Robo-Bee’s flight, you’ve got to wonder whose working on the crashes?  Put another way, Robo-Bee crashes because it can’t land.  And landing is the most challenging maneuver of successful flight.  What insect, do you suppose, displays the most precise and graceful skill in landing?  You guessed it.  Landing is one of the bee’s most amazing abilities.

            Not only are bees remarkable for how they land, but where they land sets them apart from other airborne insects as well.  Bees can land anywhere – not just on flat surfaces but, also, on irregular, ridged, and vertical surfaces.  Still, knowing that the bees “can do it” is one thing.  Understanding “how they do it” is another.

            But bees can do something most other flying insects can’t.  They can land almost anywhere smoothly.  In order to land smoothly, a flying object must slow down almost to a stop at the landing location.  So, landing isn’t just about the bee putting its, er, ah, . . . feet (or whatever) onto the ground.  Landing is about speed and distance. 

            To do it right, you have to estimate your distance from the place you intend to land and vary your speed so that you have just about stopped by the time you reach your intended landing spot.  At least, you have to do all this if you want the bee’s characteristically smooth landing.  A crash is a landing too.  Just not a smooth one.

            In the old days, human pilots made these estimations using nothing more than their vision.  As human beings, we have two eyes set slightly apart.  Each eye relays a slightly different image to the brain.  Our brain compensates so that we “see” only one image.  But, without even realizing it, the slight differences in the two images are translated by the brain into an awareness of the relative distances of the objects around us. 

            Everything from navigating around objects in our home to driving on the roads would present difficulties, and even dangers, without our “stereo” vision.  And, with nothing more than this vision, aviators used to gage their speed relative to the distance of the chosen landing strip.  Then, they would try to bring their aircraft to as slow a speed as possible at the point at which the landing gear made first contact with the ground.

            However, pilots don’t use plain old vision these days.  Sophisticated computers estimate distances for professional pilots.  This can be done with or without the aid of global positioning signals.  Computers can use no more than bits of data, from radar and lasers, to estimate distance from the destination, direction, and speed.  With this information, an aircraft can be brought to the slowest possible speed at the moment the landing gear touch the ground.

            But bees don’t have the equivalent of human “stereoscopic” vision.  And they don’t have the benefit of computers.  So, how do the bees land so well?  The fact that bees seem to be able to land almost anywhere has provoked extensive study. 

            A new discovery about just how bees accomplish their remarkable landings has been reported in the Proceedings of the National Academy of Sciences.  The process is surprisingly simple.  Professor Mandyam Srinivasan at the University of Queensland explains that bees “watch” an object, their destination, as they fly toward it.  As they approach their intended landing place, the visual image of the place seems to get bigger.  Just how fast the image of the destination seems to increase in size, tells the bee when to slow down and stop.  However unfamiliar this method must seem to human beings, it allows bees to make almost perfect landings most of the time without any other information about distance or speed.

            Professor Srinivasan uses an analogy from the kind of simulated space travel you might see in a computer game or even a “stars” screen saver.  As you approach a particular star, two things happen.  First, the other stars around your destination seem to move away.  And, second, your destination star appears to become larger.  

            In bees, nature has used these simple observations to create an amazing navigation and flight system.  And researchers have been able to reduce the bees’ landing strategy to a mathematical model for guiding landings.  This “vision-based system” needs nothing more sophisticated than a video camera of the type “found in smart phones.”

            An insect-sized mini-drone would not need radar, sonar or laser beams to determine surface speed and distances for landing.  Dropping this expensive equipment would not only make the mini-drone cheaper, but the lighter weight would extend the drone’s range.  Best of all, losing the radar, sonar, and laser beams eliminates detectable electronic signatures, which could make this tiny drone “visible” – detectable to tracking technologies.

            Just using the bee as a model will allow an insect-sized mini-drone to, someday, make the perfect landing.  And, also, make mini-drone technology cheaper, extend its range of operation, and increase its “stealth.”  So, even DARPA is studying bees.

M Grossmann of Hazelwood, Missouri & Belleville, Illinois

2 October 201

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