Modeling and experiments of IPMC actuators for the position precision of underwater legged microrobots

Nowadays, underwater microrobots show significant potential of monitoring ocean currents and chemical agents, studying the animal migration, depth measurements, pollution detection, and video mapping in limited space. Compact structure, multi-functionality, flexibility, and position precision are normally considered incompatible characteristics for underwater microrobots. To accomplish our objectives, we designed several bio-inspired underwater microrobots with compact structure, flexibility, and multi-functionality by using ionic polymer metal composite (IPMC) actuators. However, the position precision of them was not high enough. To implement a high position precision of developed underwater microrobots, we proposed an electromechanical model of the IPMC and analyzed the deformation and actuating force of the IPMC equivalent cantilever beam, which could be used as biomimetic legs, fingers or fins of the underwater microrobot. Then we evaluated the tip displacement of the IPMC actuator experimentally. The experimental deflections fitted the theoretical values very well when the driving frequency was larger than 1 Hz. In addition, by using the IPMC equivalent cantilever beam model, we developed several underwater legged microrobots. A predetermined trajectory tracking experiment was carried out to evaluate the position precision of developed legged microrobot.