Design and Control of Multi-Rigid Link Pectoral Fins Using Virtual Spring-Damper System for a Manta Ray Robot

Biomimetic robots have the advantages of propulsion efficiency and maneuverability. Manta ray robots with soft, flexible, and distributed multi-stage pectoral fins have been proposed. Robots with flexible fins can be propelled by varying the phase difference and amplitude of each pectoral fin. However, it is still difficult to uniquely define the state of soft, flexible fins, which are passively controlled. Robots with soft and flexible fins are susceptible to various water conditions. In this study, we designed a manta ray robot with multi-rigid link pectoral fins that can actively reproduce uniquely define bending. To actively reproduce the bending and propulsion of the manta ray, we propose a virtual spring-damper system. The validity of this design and control methodwas verified through experiments on the movement trajectories and swimming. It was found that the manta ray robot using the proposed design and control reproduced bending and achieved high speed and turning performance. This shows that the proposed design and control methods exhibit the same or better performance than the soft fins. These methods expected to be further applications for biomimetics robots, enabling active control, with uniquely defined bending and fin performance.