Development of a sea snake-like underwater robot

Developing soft fish robots by biomimetic approach is a useful way to achieve high efficiency, high performance and fish-like motions. Comparing to the conventional rigid fish robots, the design and control of soft fish robots are difficult, because the coupling between the flexible structure and fluid should be considered. But the coupling problem is very difficult to be solved due to large deformation and complicated dynamics. This is main reason why the design method for soft fish robots has not been established while many trial developments of soft fish robots have been done up to now. It motivates us to realize the design and control of soft fish robots based on the analytical simulation, by considering the coupling between flexible structure and fluid. In this paper, development of a sea snake-like underwater robot using piezoelectric fiber composite is described. First, the propulsion mechanism of sea snakes is discussed to provide hints for design and control of soft sea snake-like underwater robots. Next, a sea snake-like underwater robot is designed based on the modal analysis of the robots structure in the fluid and a prototype is made. Finally, the performance of the prototype is investigated by experiments.