Question

Discussion of electromagnetic principles that enable motion in servo motor

Answer 1

Servomotor is basically a DC motor (at times can be an AC motor too) with special purpose components - potentiometer, gear assembly and and a control circuit. So, as far as the electromagnetic principle governing the motion of servo motor are concerned, it is the same as that for an ordinary DC motor (or AC motor) , i.e., whenever a current-carrying conductor is placed in a magnetic field, it experiences a mechanical force.

Servomechanism: Servomotor is an automatic closed loop control system. The motor rotates, when it is given an input, which in turn, is an amplified error signal. Error signal refers to the difference between a set reference value and the actual output of the motor (i.e., angular displacement of the motor shaft). So, instead of a variable input, the servomotor is fed by a feedback signal (the error signal) and it rotates as long as there is a logical difference between the reference input signal and output of the system. Once, it attains the set reference value at the output, it stops rotating. The output signal corresponding to the motor rotation, is generated by the potentiometer, compared with the set value to generate error signal, amplified and given as input to the servomotor; the gear assembly, by reducing the speed, converts the small torque generated by the motor to a practically useful larger value.

Thus, servomotor is an electrical device which can push or rotate an object with great precision (when you want to rotate an object through some specific angles or distance).