Patent ID: 7777481

Claim:
A linear motion assembly, comprising: a first body; a second body; a plurality of recirculating ferrous rolling elements disposed between said first body and said second body to enable low friction translation of said first body and said second body relative to one another; a permanent magnet carried by one of said first body or said second body; a pair of ferrous conductors, one of said ferrous conductors being attached to said permanent magnet to carry magnetic flux therefrom and the other of said ferrous conductors being attached to said permanent magnet to return the magnetic flux thereto, each of said ferrous conductors having a free end; a microprocessor; an inductor coil wound about one of said ferrous conductors, said inductor coil being arranged in communication with said microprocessor; said free ends being spaced from one another by a gap to provide an open circuit between said free ends; said gap being substantially closed by the presence of said ferrous rolling elements to provide a closed circuit, said closed circuit imparting an electromotive force on said inductor coil; and said microprocessor detecting the presence of said ferrous rolling elements closing said gap from said electromotive force and the absence of said ferrous rolling elements across said gap from said open circuit.