Design of a wireless hybrid in-pipe microrobot with 3 DOFs

In recent years, microrobot in medical and industrial fields is developed. In this paper, we developed a wireless in-pipe microrobot with 3 DOFs to implement the locomotion and mechanism of the microrobot in small area such as organ of digestion or small plumbing for medical and industrial applications. Firstly, we developed a novel type hybrid in-pipe microrobot which could swim wirelessly in the liquid by using outside magnetic field. We proposed a hybrid motion composed of spiral motion and fin motion to take advantage of strong point each motion. Secondly, we proposed the 3D magnetic field system to enable multi DOFs locomotion to the microrobot. Therefore, we developed 3 axes helmholtz coil system to implement stability and multi directivity of the magnetic field. Based on the experimental results, we also confirmed the same amount of regular magnetic field even 3 axes coil. Thirdly, we evaluated the mechanism of this microrobot to realize its characteristics. In spiral motion, we evaluated the relationship between limit of rotating speed and operating voltage based on equation of rotating motion. In fin motion, we evaluated the resonance frequency of the fin to confirm the characteristic of frequency. Fourthly, we evaluated swimming speeds for spiral motion, fin motion, and hybrid motion in a pipe filled with water. The results indicated when the microrobot drove at low frequencies in horizontal direction, the fin motion was superior to the spiral motion and when the microrobot drove at high frequencies in the horizontal direction, the spiral motion was superior to the fin motion. Also, we confirmed this hybrid microrobot can move even vertical direction. We need more research to realize the microrobot flourishing medical and industrial fields.