[FT] Mobile mine field(?) suggestions sought

I'd like suggestions on modelling fields of small, unmanned weapons
platforms that would move slowly towards intruders, with the idea of
overwhelming by numbers.

I'd need them to track targets, build to killing mass against anything
that
would stick around long enough, but relatively ineffective against
hit-and-run.

Please note that I'm most interested in suggestions on modelling
'behavior', auto-rules for a relatively amorphous pattern of slow-moving
platforms.

The_Beast