[Tyler]

Biologists Discover Cellular Bang-Bang Controller
     

A robots.net reader sent us a link to a Princenton
news release describing research by Raj Chakrabarti and others on
cellular proteins that act as
adaptive machines, guiding biological evolution. Our reader notes,
proteins configured as bang-bang controllers steer random mutations
in deterministic directions;  robot navigation algorithms as a mechanism
for self-directed evolution. A bang-bang
controller is a simple algorithm that bounces between two extremes
like a household thermostat. This type of control is commonly used in
robotics and, it now appears, is an integrel part of every living cell.
The cellular bang-bang controller guides random mutations in a way that
corrects imbalances, even repairing mutations that disable the
controlling protein chains. This is also fascinating to anyone who
appreciates cybernetics. It's a great example of a cybernetic feedback
loop, much like a centrifugal regulator on a steam engine. This disovery
is likely to make some waves in the field of evolutionary biology as it
suggests a cellular mechanism guiding the way the cell responds to
natural selection. Will it make waves in robotics as well? I doubt it
will make anyone throw out proportional control, but I wonder if we'll
see bang-bang being favored in biomorphic robot designs? You can read
more about this research on Raj
Chakrabarti's home page where you can also find a copy of the full
paper, "Mutagenic
evidence for the optimal control of evolutionary dynamics" (PDF format).
   

http://robots.net/article/2694.html