The servo motor, also known as the motor in the automatic control system, for the implementation of components of the received electrical signal into an angular displacement or angular velocity of the output of the motor shaft. Divided into two major categories of DC and AC servo motor, its main feature is that when the signal voltage is zero, no rotation, speed and uniform decline with increasing torque.

    Inside of the servo motor rotor is a permanent magnet, the drive control of the U / V / W three-phase electric forming electromagnetic field, the rotor is rotated under the action of this magnetic field, the feedback signal to a drive device at the same time the motor carrying the coding device, the drive according to the feedback value and the target compare values, adjust the angle of rotation of the rotor. The accuracy of the servo motor is determined by the accuracy of the encoder (number of lines).