Fundamental analysis for design and control of soft fish robots using piezoelectric fiber composite

Developing fish robots by biomimetic approach is a useful way to achieve more efficient, high-performance and fish-like motions. And it is very important to make the fish robots as soft as fishes. For this purpose, we are developing soft fish robots using flexible piezoelectric fiber composite (PFC) as actuators together with soft body structure. Comparing to the conventional rigid fish robot, the design and control of soft fish robots are difficult, because the coupling between the flexible continuum and fluid should be considered, which 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 challenge the design and control problem of soft fish robots based on the analytical simulation with considering the coupling between flexible structure and fluid. In this paper, fundamental analysis for the design and control of soft fish robots using PFC is described. First, modeling of driving from input voltage of PFC to the displacement output of robot in the air is established and improved by comparing experimental results with simulation results. Next the method for structural design of fish robot is performed by modal analysis in the fluid. Finally, a new design of fish robot by the method is shown.