Actuation apparatus

摘要

An actuation apparatus for positioning a workpiece includes a movable electrically conductive member connectable to said workpiece, first electromagnetic actuating means energizable by a first AC voltage source to produce a first force acting on said movable member in a first direction, and second electromagnetic actuating means energizable by a second AC voltage source to produce a second force acting on said movable member in a second direction opposite to said first direction. The forces produced on the movable member by the actuating means are brought about by the interaction of eddy currents induced in the movable member with the magnetic fields produced by the first and second actuating means. The movable member can be moved to a desired position by appropriate energization of the first and second actuating means such that the first and second forces are equal at the desired position.