August 13, 2004 | David F. Coppedge

Dragonfly Inspires Hi-Tech Hovercraft for Mars

Exclusive  Dragonflies possess not only compound eyes like other insects, but additional “simple” eyes called ocelli (sing., ocellum) with full-field retinas like mammalian eyes.  These function as a “horizon sensor/attitude reference system,” according to an engineer trying to copy it.  In an engineering project supported by the military and aerospace, Dr. Jaavan Chahla and an Australian team have built mechanical ocelli that allow small drone planes and helicopters to mimic the dragonfly’s ability to achieve low-altitude flight without hitting obstacles.  In a presentation at JPL August 13, he showed film clips of flight tests that apply the dragonfly’s processing of “optical flow”, the information that comes from a shifting angles of light as you move.  Since this is not dependent on heavy inertial guidance systems, magnetic compasses or other flight technologies, it permits the development of low-mass flight hardware suitable for Mars, which has no useful magnetic field.
    Commenting on the dragonfly’s abilities, Chahla stated that it (and other insects) are able to process huge amounts of data with 8-19 millisecond response – a volume of data man-made sensors have trouble managing.  Yet they do it with a tiny brain with 0.01% the neurons in a human brain.  All insects rely on optical flow sensing, he said.  It’s a useful sense, because as a passive response system, it does not depend on echoes or transmissions, as with radar, and also is independent of wind motion.  Another inherent problem with horizon sensors is failure when the sun falls into the field of view.  The dragonfly has overcome this failure mode using multispectral processing in the green and UV bands.
    Insects also have rapid ability to “self-bootstrap” or respond quickly to new information, for instance when released into the open from a dark enclosure.  This has been a challenge for humans to emulate.  Another challenge has been hovering in place.  Optical flow sensing is easier in a moving environment, but more difficult when the horizon is stationary.  Chahla showed a film clip of a dragonfly hovering next to a blade of grass moving in the wind.  The dragonfly’s motion tracked the movement of the grass almost instantaneously.  Having worked with model helicopters, Chahla seemed particularly impressed with that ability.
    An abstract of an earlier paper by Chahla et al. is available on Journal of Robotic Systems.  A diagram (PDF format) of a dragonfly head with ocelli can be found at University of California Press.

The simplest, ordinary things in the garden or out on a nature walk are really extraordinary when you look at them in detail.  No one respects nature’s abilities more than a human engineer who has tried to figure it out and reverse engineer them.  When our brightest designers can barely keep up with the observed specifications in the insect world, are we to honestly believe that blind, undirected natural laws achieved these natural abilities without a Designing intelligence?

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