Development of a novel underwater microrobot with proximity sensors

In the field of underwater monitoring for applications such as pollution detection and video mapping in limited space, underwater microrobots are urgently demanded. Compact structure, multi-functionality, and flexibility are normally considered as incompatible characteristics for underwater microrobots. To implement these purposes, we have developed several types of microrobots with both compact structure and flexible locomotion. However, they just implemented one or two motions, such as walking, rotating, swimming, grasping, or floating motions. So, in this paper, we designed a novel type of biomimetic locomotion employing ionic polymer metal composite (IPMC) actuator as one-DOF leg. Then we proposed a new type of underwater microrobot using ten ionic polymer metal composite (IPMC) actuators as legs, fins, or fingers, which could implement walking, rotating, floating, swimming, and grasping motions at the same time. Also, we developed a prototype of this underwater microrobot and carried out some experiments to evaluate its walking, rotating, and floating speeds. In addition, we used two IPMC actuators as fingers to grasp some small objects, and used other two actuators as fins to implement the swimming motion like a frog. To implement the closed-loop control for the microrobot, we used three proximity sensors to detect the object or avoid the obstacle while walking.