Haystack encased needle extractor.

This is a simple robot for extracting needles from haystacks. A wheeled chassis supports a lightweight arm with a tweezer at the end.

The arm picks up an item from the mixed needle/hay pile and sets it across two electical contacts. A quick continuity test checks whether the item is a conductive needle, or non conductive hay.

Hay is piled on one side, needle(s) on the other. The device iterates through the entire pile until all needles have been extracted.

Note that this may not work with wet hay.