Correct Answer - Option 3 : servo motors
Explanation:
Servomotors are special electromechanical devices that produce precise degrees of rotation. Servomotors are also called control motors as they are involved in controlling a mechanical system. The servomotors are used in a closed-loop servo system. A feed drive consists of a feed servomotor and an electronic controller. The feed motor has certain special characteristics, like constant torque and positioning which are done by servo-motors.
Synchronous Motors: In the synchronous motor the stator poles are wound with coils and rotor is a permanent magnet and is supplied with current to create fixed polarity poles.
Induction Motor: In the case of induction motor, the stator is similar to the synchronous motor with windings but the rotors’ construction is different.
Stepper Motor: A stepper motor is a pulse-driven motor that changes the angular position of the rotor in steps. Due to this nature of a stepper motor, it is widely used in low cost, open-loop position control systems.
