Rotary encoders track motor shaft movement for myriad pieces of industrial equipment and commercial
devices. For industrial applications, incremental encoders (used when only relative position is needed, or
cost an issue) are typically used with ac induction motors. In contrast, absolute encoders (which give a
different binary output at each position, so shaft position is absolutely determined) are often paired with
permanentmagnet
brushless motors in servo applications. Often, encoder feedback is used to ensure
synchronization of the motor stator and rotor positions to drivesupplied
current, so current is applied to
the windings when the rotor magnets are within a proper position range (to maximize torque.)