Tuna robotics: A high-frequency experimental platform exploring the performance space of swimming fishes

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 hertz). To explore the high-frequency fish swimming performance space, we designed and tested a new platform based on yellowfin tuna (Thunnus albacares) and Atlantic mackerel (Scomber scombrus). Body kinematics, speed, and power were 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 millimeters long) can achieve a maximum tail beat frequency of 15 hertz, which corresponds to a swimming speed of 4.0 body 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 body lengths per second. The Tunabot has a range of ~9.1 kilometers if it swims at 0.4 meter per second or ~4.2 kilometers at 1.0 meter per second, assuming a 10–watt-hour 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.

Tuna locomotion: a computational hydrodynamic analysis of finlet function

“…A no-slip boundary condition was applied at the model surface. Previous numerical results of tuna [13,14,23,24] and jackfish [16] swimming and recent experimental flow visualization of robotic tuna models [25,26] both show that the local flow past the posterior bodies of the fishes/model was converging to the posteriorly narrowed bodies. Therefore, the incoming flow U 1 in this paper was set to be parallel to the stroke plane of finlets to mimic the local flow condition of finlets as in tuna swimming.…”

Walking with Salamanders: From Molecules to Biorobotics

“…We also hypothesize that all vertebrates share the same building blocks in their spinal cords, but that the respective roles of central and peripheral mechanisms might be different in different animal species and that they have changed during evolution, with generally a more important role of central pattern generators in anamniotes and a more important role of sensory feedback (and descending commands/modulation) in higher vertebrates. Computational methods and robotics will allow one to test this hypothesis and will facilitate investigation of the interplay between the different components underlying locomotion, in particular by taking into account the mechanical properties of the body (e.g., fin properties for swimming [103]) and of the environment (e.g., interactions with granular media like sand [98]).…”

Field testing of biohybrid robotic jellyfish to demonstrate enhanced swimming speeds

“…Examples of bioinspired aquatic robots include robotic fish [16][17][18], manta rays [19][20][21], sea stars [22,23], and jellyfish [24][25][26][27][28][29], including systems that have been deployed in real-world environments [16,24].…”