the role of the servo motor controller is the input voltage signal,The control voltage)Into a shaft angular displacement or angular velocity output, in automatic control system as actuators, so also known as force motor, servo motor, its biggest characteristic is: is rotor rotating immediately when the control voltage, no control voltage rotor immediately halt. Axis of steering and speed is determined by the direction and size of the control voltage. Divided into two major categories of ac and dc servo motor controller. Below I give everybody to explain the dc servo motor controller. Dc servo motor controller: 1, the basic structure of the traditional dc servo electric motor essence is common dc motor capacity is small, he wound type and permanent magnet type two kinds, the structure and common dc motor in the same structure. Cup armature dc servo motor rotor made of non-magnetic materials hollow cylindrical cup, rotor is lighter and make the moment of inertia of small, rapid response. In rotor made of soft magnetic materials between the inside and outside of the stator rotating, the air gap is bigger. Brushless dc servo motor using electronic commutation device instead of the traditional brush and commutator, make it more reliable. The stator core structure and common dc motor basic same, it is embedded with multiphase winding, rotor permanent magnet materials. 2 basic working principle of the traditional dc servo motor's basic working principle and common dc motor are exactly the same, relying on the effect of armature current and air gap flux produce electromagnetic torque, to rotate the servo motor. Usually adopt the armature control mode, that is, under the condition of the excitation voltage unchanged, by changing the armature voltage to adjust speed. The armature voltage is smaller, the speed is lower; The armature voltage is zero, the motor stalling. Due to the armature voltage is zero armature current is zero, also do not produce electromagnetic torque motor, there will be no 'rotation'.