Mesobot: An Autonomous Underwater Vehicle for Tracking and Sampling Midwater Targets

Abstract

Mesobot, a new class of autonomous underwater vehicle, will address specific unmet needs for observing slow-moving targets in the midwater ocean. Mesobot will track targets such as zooplankton, fish, and descending particle aggregates using a control system based on stereo cameras and a combination of thrusters and a variable buoyancy system. The vehicle will also be able to collect biogeochemical and environmental DNA (eDNA) samples using a pumped filter sampler.

A Computational Model for Tail Undulation and Fluid Transport in the Giant Larvacean

“…At the start of the cycle (Figure 2a), the tail's deformation is a result of the previous cycle's activation wave, with activation present on both the top and bottom portion of the tail. As the wave of tension travels down the tail (Figure 2b), we note both the spatial extent of activation as a function of α, with no activation present in the last third of the tail, due to A re f = A = 4 6 . In the last third of the tail, the resulting kinematics are a product of the passive elastic properties of the tail and the local fluid environment.…”

“…For the cases where the activation region extends towards the midpoint of the tail (A = 3 6 , 4 6 ), the active portion allows for both the tail wave to form as a result of the applied stress and actuates the completely passive trailing edge portion of the tail. Treating the spatial limit of the active portion (X = AL) as an inflection point, we measured the relative angle of the inflection point with respect to the trailing edge to be between −30.7 • and 32.4 • for the A = 4 6 case and between −25.7 • and 26.9 • for the A = 3 6 case. These angles correspond to the observed inflection angles of other organisms' flexible propulsors [27].…”

“…Animal-fluid interaction studies have largely focused on animals that can be maintained in a laboratory environment. Recent developments that improve access to other biological modelsparticularly in underwater environments-are opening up new lines of inquiry [2][3][4][5][6]. The recognition that swimming animals create coherent structures in their wakes [7,8] has led to more detailed studies of how particular morphological features, like peduncles in whales [9] and denticles in sharks [10], can play a role in drag reduction and ultimately swimming performance.…”

Guidance for Autonomous Underwater Vehicles in Confined Semistructured Environments

“…In open water or semiconstrained environments, in addition, it is possible to establish communication paths with surface stations and/or vehicles, providing the UV with different levels of assistance. In this line, and mostly through the use of a physical tether providing a high bidirectional throughput between the UV and the assisting platform and allowing the continuous or intermittent intervention of a human operator, ROVs or UVs with supervised autonomy, respectively, have been extensively used [ 18 , 22 , 23 ]; a fast communication channel with the computational resources of a surface station could also be used to derive part of the computational tasks of the UVs to the latter. Linked to this capacity to establish a communication channel, in this case an acoustic channel, with GPS-enabled surface platforms, the UVs can obtain accurate positioning using long or short baseline (LBL/SBL) techniques [ 19 , 24 ].…”

“…The need for high maneuverability and positional control has been signaled in the literature with the departure from the forward-moving torpedo-shaped submersibles typical from open water exploration [ 20 , 21 ] to, often, ellipsoidal [ 28 ], spherical [ 23 ], or cubical [ 22 ] shapes, able to perform movements in six degrees of freedom (DOF) and with hovering capabilities: hence their generic name, hovering AUVs (HAUVs). Following this line of work, the DEPTHX UV was carried out the exploration and mapping of hot springs [ 28 ]; the submersibles Sentry [ 29 ] and Mesobot [ 22 ] performed oceanographic surveys and observations of marine life; and U-CAT [ 26 ], IMOTUS-1 [ 23 ], and and SUNFISH [ 27 ] were used to autonomously explore and map archaeological sites, storage tanks, and underwater caves, respectively. These three latter works, which can be considered the closest existing works to our UX-1 robot not only in terms of their field of application but also regarding their guidance, are discussed further below.…”