Microrobot and microrobot system

1 . A microrobot comprising:

a rotating shaft;

a main magnet fixedly coupled to the rotating shaft;

a first support body fitted around the rotating shaft, and rotatable about the rotating shaft;

a first driving magnet fixedly coupled to the first support body, and having a magnetic moment having a magnitude that is different from a magnitude of a magnetic moment of the main magnet; and

a plurality of first legs coupled to an outer circumferential surface of the first support body,

wherein, in a first mode in which an external rotating magnetic field having a frequency lower than a step-out frequency of the main magnet and a step-out frequency of the first driving magnet applied, the main magnet and the first driving magnet are aligned in a direction of the external rotating magnetic field and rotate together, and

wherein, in a second mode in which an external rotating magnetic field having a frequency lower than the step-out frequency of the main magnet but higher than the step-out frequency of the first driving magnet applied, the first driving magnet rotates less than in the first mode, and the main magnet rotates in synchronization with the external rotating magnetic field.

2 . The microrobot of claim 1 , wherein the main magnet has the magnetic moment that is greater than the magnetic moment of the first driving magnet.

3 . The microrobot of claim 1 , further comprising:

a second support body fitted around the rotating shaft on an opposite side of the first support body with the main magnet interposed between the first support body and the second support body, and rotatable about the rotating shaft;

a second driving magnet fixedly coupled to the second support body, and having a magnetic moment having a magnitude that is different from a magnitude of the magnetic moment of the main magnet; and

a plurality of second legs coupled to an outer circumferential surface of the second support body.

4 . The microrobot of claim 3 , wherein the magnetic moment of the main magnet is greater than the magnetic moment of the second driving magnet.

5 . The microrobot of claim 3 , wherein the magnitude of the magnetic moment of the second driving magnet is equal to the magnitude of the magnetic moment of the first driving magnet.

6 . The microrobot of claim 1 , wherein the main magnet includes a cylindrical magnet, and is configured such that an N-pole and an S-pole are arranged opposite to each other with the rotating shaft interposed therebetween.

7 . The microrobot of claim 1 , further comprising a drill tip fixedly coupled to a front end of the rotating shaft, and configured to rotate integrally with the rotating shaft.

8 . A microrobot system comprising:

a microrobot in which a main magnet is fixedly coupled to a rotating shaft, a first support body having an outer circumferential surface to which a plurality of legs is coupled integrally with a first driving magnet so as to be fitted around the rotating shaft, and the first support body and the first driving magnet are rotatable about the rotating shaft; and

a magnetic field generator configured to generate an external rotating magnetic field on an outside of the microrobot,

wherein the main magnet and the first driving magnet have magnetic moments having different magnitudes,

wherein, in a first mode in which the external rotating magnetic field having a frequency lower than a step-out frequency of the main magnet and a step-out frequency of the first driving magnet applied, the main magnet and the first driving magnet are aligned in a direction of the external rotating magnetic field and rotate together, and

wherein, in a second mode in which the external rotating magnetic field having a frequency lower than the step-out frequency of the main magnet but higher than the step-out frequency of the first driving magnet is applied, the first driving magnet rotates less than in the first mode, and the main magnet rotates in synchronization with the external rotating magnetic field.

9 . The microrobot system of claim 8 , wherein the microrobot includes a second support body and a second driving magnet, which are fitted around the rotating shaft on an opposite side of the first support body with the main magnet interposed between the first support body and the second support body and the second driving magnet, and coupled integrally with each other so as to be rotatable about the rotating shaft, and

the second driving magnet has a magnetic moment having a magnitude that is different from the magnitude of the magnetic moment of the main magnet.