When PICs Fly
by Tony Pratkanis and Bob Allen
Bees do it. Birds do
it. Why shouldn’t
robots do it, too
— fly through the air,
that is? Although there
have been some military
and commercial robots
that fly, there have been
very few homebrewed
One reason that flying robots have not filled the
airspace in backyards and robotics clubs is because flight
imposes engineering obstacles that must be overcome.
These obstacles are similar to those that confronted the
early versions of bees and birds. In order to fly, bees and
birds developed the ability to navigate in three-dimensional
space and overcame weight limitations that kept them
Our robotic blimp mimics many of these developments
so we decided to call our flying robot Apis Mellifera,
which is the scientific name for the western honey bee.
Apis Mellifera is a blimp-based robot that flies around in
three-dimensional space, hugging either the floor or ceiling,
all the while avoiding obstacles.
The fossil record and recent scientific experiments tell
the story of the evolution of flight in bees and birds. Our
story of robots taking flight is told in the next few pages
of SERVO Magazine that is currently in your hands. In
telling our story, we will compare how evolution
“engineered” bees and birds for flight, with our own
efforts to design a flying robot.
Our story begins a little over a year ago. Bob Allen (the
50 SERVO 04.2008
hardware guy) visited the home of Tony Pratkanis (the
software guy) where he found Tony working on an
autonomous blimp. This primitive version of a flying robot
consisted of two blimp envelopes, a large solderless
breadboard, motors on each envelope, and a large balsa
wood gondola tying it all together. Proto-Apis Mellifera,
as we will call it, measured 0.7 meters by 1.32 meters or
about the dimensions of a medium-sized hawk.
This monstrosity was reminiscent of Archaeopteryx,
a birdlike creature that lived over 150 million years ago.
Archaeopteryx was halfway between a modern bird (with
modern feathers) and an ancient dinosaur (with heavy
toothed jaws that limited flight). Over the next 85 million
years, the descendants of Archaeopteryx would shed
those toothed jaws, develop hollow, light-weight bones,
and eliminate heavy appendages in order to develop the
flying ability of modern birds.
In order for proto-Apis Mellifera to evolve into a
capable flying machine, it, too, would need to shed
weight so that all of its anatomical features (motors,
sensors, processors, wires, and batteries) could be carried
by a single blimp envelope. The payload capacity of a single
envelope filled with helium is just about 150 grams (or
about the weight of 1,500 honey bees or one parakeet).
Fortunately, with Bob’s knowledge of hardware, it didn’t