Meeting Abstract
Tuna and related scombrid fishes are high performance swimmers that often operate at high frequencies, especially during behaviors such as escaping from predators or catching prey. This contrasts with most fish-like robotic systems that typically operate at low frequencies (< 2 Hz). To explore the high-frequency fish swimming performance space, we design and test a new platform based on yellowfin tuna (Thunnus albacares) and Atlantic mackerel (Scomber scombrus). Body kinematics, speed, and power are measured at increasing tail beat frequencies to quantify swimming performance, and to study flow fields generated by the tail. Experimental analyses of freely swimming tuna and mackerel allow comparison with the tuna-like robotic system. The Tunabot (255 mm long) can achieve a maximum tail beat frequency of 15 Hz, which corresponds to a swimming speed of 4.0 lengths per second. Comparison of midline kinematics between scombrid fish and the Tunabot shows good agreement over a wide range of frequencies, with the biggest discrepancy occurring at the caudal fin, primarily due to the rigid propulsor used in the robotic model. As frequency increases, cost of transport (COT) follows a fish-like U-shaped response with a minimum at ~1.6 BL/s. The Tunabot has a range of ~9.1 km if it swims at 0.4 m/s or ~4.2 km at 1.0 m/s, assuming a 10 Wh battery pack. These results highlight the capabilities of high frequency biological swimming and lay the foundation to explore a fish-like performance space for bio-inspired underwater vehicles.
