image: Mother
and child. Credit: Nick Saffell
(August 14, 2015) Researchers
have observed the process of evolution by natural selection at work in robots,
by constructing a ‘mother’ robot that can design, build and test its own
‘children’, and then use the results to improve the performance of the next
generation, without relying on computer simulation or human intervention.
Researchers led by the University of Cambridge have built a
mother robot that can independently build its own children and test which one
does best; and then use the results to inform the design of the next
generation, so that preferential traits are passed down from one generation to
the next.
Without any human intervention or computer simulation beyond
the initial command to build a robot capable of movement, the mother created children
constructed of between one and five plastic cubes with a small motor inside. In
each of five separate experiments, the mother designed, built and tested
generations of ten children, using the information gathered from one generation
to inform the design of the next. The results, reported in the open access
journal PLOS One, found that preferential traits were passed down through
generations, so that the ‘fittest’ individuals in the last generation performed
a set task twice as quickly as the fittest individuals in the first generation.
“Natural selection is basically reproduction, assessment,
reproduction, assessment and so on,” said lead researcher Dr Fumiya Iida of
Cambridge’s Department of Engineering, who worked in collaboration with
researchers at ETH Zurich. “That’s essentially what this robot is doing – we
can actually watch the improvement and diversification of the species.”
For each robot child, there is a unique ‘genome’ made up of
a combination of between one and five different genes, which contains all of
the information about the child’s shape, construction and motor commands. As in
nature, evolution in robots takes place through ‘mutation’, where components of
one gene are modified or single genes are added or deleted, and ‘crossover’,
where a new genome is formed by merging genes from two individuals.
In order for the mother to determine which children were the
fittest, each child was tested on how far it travelled from its starting
position in a given amount of time. The most successful individuals in each
generation remained unchanged in the next generation in order to preserve their
abilities, while mutation and crossover were introduced in the less successful
children.