Flagellate Underwater Robotics at Macroscale: Design, Modeling, and Characterization

Prokaryotic flagellum is considered as the only known example of a biological wheel, a system capable of converting the action of rotatory actuator into a continuous propulsive force. For this reason, flagella are an interesting case study in soft robotics and they represent an appealing source of inspiration for the design of underwater robots. A great number of flagellum-inspired devices exists, but these are all characterized by a size ranging in the micrometer scale and mostly realized with rigid materials. Here, we present the design and development of a novel generation of macroscale underwater propellers that draw their inspiration from flagellated organisms. Through a simple rotatory actuation and exploiting the capability of the soft material to store energy when interacting with the surrounding fluid, the propellers attain different helical shapes that generate a propulsive thrust. A theoretical model is presented, accurately describing and predicting the kinematic and the propulsive capabilities of the proposed solution. Different experimental trials are presented to validate the accuracy of the model and to investigate the performance of the proposed design. Finally, an underwater robot prototype propelled by four flagellar modules is presented.

Automated summary

The Prokaryotic flagellum serves as a biological wheel that can convert rotating motion into continuous propulsion, serving as inspiration for the design of macroscale underwater propellers. The theoretical model accurately describes the propulsive capabilities of the propellers inspired by flagellated organisms, which are validated through experimental trials. Ultimately, an underwater robot prototype propelled by these flagellar modules is presented.