For my term project I am looking for techniques that are used to control multiple objects.

Audience – rAndom international

Royal Opera House: Audience. from rAndom International on Vimeo.

And also, maybe it is ambitious: school of fish behavior.
CEATEC: Nissan robots avoid traffic accidents and congestion

Wavefunction by Rafael Lozano-Hemmer. An array of chairs that move up and down responding to the presence of the public by creating waves that propagate over the exhibition room.

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To control multiple objects I am thinking of using Arduino with shift registers. But how does the object communicate with each other (ideally in wireless), XBee is one option.
(Overall, the technical difficulty seems to be the main issue for me).