Position feedback eliminates homing routines

Here's how APF works. The system generates an electromagnetic pulse that travels the length of the linear transducer, creating a circular magnetic field around the transducer. A magnet embedded in the carrier is mounted with its magnetic field at right angles to the transducer's electromagnetic field. Where the two fields intersect, a magnetorestrictive effect elastically deforms the transducer. This deformation moves away from the magnet in both directions at 9,285 fps as two mechanical waves. At the far end of the actuator a damper absorbs one wave. At the other end, a converter turns the mechanical wave into an electrical signal. The time it takes the mechanical wave to get there is proportional to the distance between the magnet and converter. By measuring this time, carrier position can be accurately determined.