Appendage morphing during metachronal swimming enables high maneuverability

Metachronal swimming, a form of locomotion characterized by the sequential movement of multiple appendages with phase shifts, is used across scales and by various oceanic invertebrates. Due to its prevalence, it is a compelling source of inspiration for bioinformed design. While most works on metachronal swimming have focused on hovering and forward motion, how metachronal swimmers maneuver still needs to be investigated. Using marsh grass shrimp (Palaemon vulgaris) as a model organism, we developed a metachronal robotic platform with morphologically accurate shrimp swimming appendages (pleopods) to isolate and modify parameters of interest to improve our understanding of this mode of locomotion. Pleopods consist of a rigid proximal segment with two appendages extending from it: the medial endopodite and the exopodite, which extends laterally and abducts/adducts during the leg beat. This talk discusses how controlling the exopodite abduction angle during the power stroke to create front-to-back and lateral differentials across multiple appendages results in rotational moments like yaw, pitch, and roll. We present simultaneous force and particle image velocimetry measurements and evaluate the contributions of particular flow features to the production of lift and thrust differentials involved in turning maneuvers. We also compare the performance of metachronal agility against a baseline of propeller-based systems. These results will aid in developing efficient and maneuverable bio-informed autonomous underwater vehicles (AUVs) that can be used for extraplanetary ocean exploration and in inaccessible areas for traditional propeller-based AUVs.