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Exercise 4.20 4 The Reactive Paradigm
[Digital Circuits]
For readers with a background in digital circuits, build one or more of the simple
creatures in Flynn and Jones’ Mobile Robots: Inspiration to Implementation 76 using a
Rug Warrior kit.

4.8 End Notes

For a roboticist’s bookshelf.
The subsumption architecture favors a hardware implementation using inexpensive
hardware. Part of the rapid acceptance of the reactive paradigm and the subsump-
tion architecture was due to Mobile Robots: Inspiration to Perspiration 76 by students in
the MIT AI Lab. The straightforward circuits allowed any hobbyist to produce intel-
ligent robots. On a more theoretical note, Rodney Brooks has collected his seminal
papers on subsumption into a volume entitled Cambrian Intelligence, 28 a nice play on
the period in evolution and on Brooks’ location in Cambridge, Massachusetts.

About Rodney Brooks.
Rodney Brooks is perhaps the best known roboticist, with his insect-like (Genghis,
Attila, etc.) and anthropomorphic robots (Cog, Kismet) frequently appearing in the
media. Brooks was one of four “obsessed” people profiled in a documentary by Errol
Morris, Fast, Cheap, and Out of Control. The documentary is well worth watching, and
there are some gorgeous shots of robots walking over broken glass giving the terrain
a luminous quality. Brooks’ reactive philosophy appears in an episode of The X-Files
on robotic cockroaches called “War of the Corophages.” The roboticist from the Mas-
sachusetts Institute of Robotics is a combination of Steven Hawking (the character is
disabled), Joe Engleberger (the bow tie), Marvin Minsky (stern, professorial manner),
and Rodney Brooks (the character says almost direct quotes from Brooks’ interviews
in science magazines).
About the “s” in subsumption.
Rodney Brooks’ 1986 paper never officially named his architecture. Most papers refer
to it as “Subsumption,” sometimes without the capital “s” and sometimes with a
capital.

Building a robot with petty cash.
Erann Gat and his then boss at NASA’s Jet Propulsion Laboratory, David Miller, cite
another advantage of behavioral robotics: you can build a mobile robot very cheaply.
In the late 1980’s, Miller’s group wanted to build a small reactive robot to compare
with the traditional Hierarchical vehicles currently used for research and to get expe-
rience with subsumption. Request after request was turned down. But they realized
that the individual electronics were cheap. So they bought the parts for their small