EMA system with gradient and uniform saddle coils for 3D locomotion of microrobot

In this paper, we study the 3 dimensional (D) locomotion of a microrobot using an electromagnetic actuation (EMA) system with gradient and uniform saddle coils. Generally, previous EMA systems have used Helmholtz and Maxwell coil pairs. For 3D locomotion of a microrobot, two pairs of coils were perpendicularly positioned and one pair of the two pairs had a rotational mechanism. With such structure, the EMA system had a large volume and consumed much driving energy. To overcome these undesirable properties, we propose an EMA system driven by saddle coils, which has the same functions as the previous EMA system but a smaller volume and less consumption of driving energy. Firstly, the locomotion mechanisms of the proposed EMA system in 2D and 3D spaces are explained. Secondly, for the accurate locomotion of the microrobot by the EMA system in a 3D space, gravity compensation is executed. Thirdly, by 3D locomotion tests of the microrobot in a test bed cube and a blood vessel phantom, the performance of the proposed EMA system is evaluated. Lastly, the proposed EMA system and the previous EMA system are compared with respect to structure and energy consumption. The results showed that the proposed EMA system has smaller volume and higher energy saving capabilities than the previous EMA system.