Meeting Abstract
Fish fins function not only in propulsion, but also to provide sensory input from the environment. Fish can sense fin ray bending using intrinsic fin sensors, and alter their behaviors based on sensor inputs. Inspired by the mechanosensory system of fish fins, we developed a bioinspired robotic prototype that integrates both soft sensing and locomotor capability. First, we used multi-material 3D printing to manufacture a soft-rayed fin mechanism which allows the fin to be erected/folded, and flap laterally. Then we fabricated soft sensors by using hyperelastic silicone elastomers (modulus: 55 kPa) with a spiral-pattern micro-channels which were infused with conductive liquid metal (eutectic gallium indium). The soft sensor possesses a circular shape, and is capable of detecting sensitive contact pressure along the normal axis. We integrated these soft sensors with an array of fiber-reinforced soft actuators that mimic the dorsal/anal inclinator and erector/depressor fin muscles. The fin prototype demonstrates the capability of detecting fin ray bending as well as differentiating the direction of external force imposed on the fin rays. We tested the fin prototype in a water tank that can generate programmable flow speeds, and simultaneously recorded the outputs of the soft sensors as well as high-speed images of fin deformation. Finally, we examined the sensory output of the bioinspired soft dorsal/anal fins on an undulatory fish robot at different body undulatory frequencies and amplitudes. Bioinspired fins with mechanosensory input may provide a new approach for underwater robotics with a proproceptive feedback capacity for navigating through the cluttered environments.
