Acoustic‐telemetry payload control of an autonomous underwater vehicle for mapping tagged fish

Abstract

Autonomous underwater vehicles (AUVs) have demonstrated superior performance for tracking marine animals tagged with individually coded acoustic transmitters. However, AUVs engaged in mapping the distribution of multiple tagged fish have not previously been able to alter search paths to achieve precise position estimates. This problem is solved by the development of payload control software (Synthetic Aperture Override, SAOVR) that allows the AUV to maneuver with trajectories favorable for solving the tag's location from a synthetic aperture. Upon tag detection during a default mission search path, SAOVR (running on an embedded guest computer) seeks permission to take over navigation from the vehicle's native system after checking constraints of geography, timing, tag identification, signal strength, and current navigation state. Permitted maneuvers are then chosen from a template library and executed before returning the AUV to the point of first deviation for continued searching of other tags. Field evaluation on moored reference tags showed a high level of predictability in the AUV's behavior at SAOVR initiation and through maneuvers. Trials suggest that this logic system is highly beneficial to AUV use for fish telemetry in challenging environments such as narrow, deep fjords, or among reefs. Any mission programmed with the AUV's native software can be run with the SAOVR package to allow scientists to easily implement and manipulate synthetic aperture geometries without altering any of the software. Further modeling can help improve template design specific to expected movements of different fish species and relative to the designation of signal strength-defined execution thresholds.

Lab-on-a-Fish: Wireless, Miniaturized, Fully Integrated, Implantable Biotelemetric Tag for Real-Time In Vivo Monitoring of Aquatic Animals

“…The ratio of dimensions for different devices in the figure corresponds to their relative scale. Despite a service life up to 17 months, acoustic transmitter M-416 [32] does not include any sensor and can only send a presence-absence signal from the tagged animal. Similarly, even though a service life up to 14 months could be achieved by the DST nano-T [33], it could merely store simple temperature measurements without wireless communication capability.…”

Tracking the Movements of Juvenile Chinook Salmon using an Autonomous Underwater Vehicle under Payload Control

“…The vehicle was instrumented with a payload control hardware/software stack that operated using software called Synthetic Aperture OVerRide (SAOVR) designed to map the location of acoustically tagged fish [22]. The software and a series of operational scripts were uploaded to an internal guest computer that communicated with the AUV's proprietary control system through the factory-installed RECON communications protocol (Hydroid Inc.).…”

“…The software and a series of operational scripts were uploaded to an internal guest computer that communicated with the AUV's proprietary control system through the factory-installed RECON communications protocol (Hydroid Inc.). After detecting a transmitter and meeting certain operational criteria [22], the vehicle deviated from its pre-programmed route and performed a maneuver designed to (1) enhance the location estimate of the tagged fish and (2) move the AUV closer to the fish to obtain proximal information on the environmental conditions associated with the location. Based on simulation results, a base-forward equilateral triangle was selected as the preferred maneuver [23].…”

“…These data were also collected for any other fish detected during the maneuver. Additional maneuvers were temporarily suspended to prevent the AUV from getting locked in a positive feedback loop [22]. Sequential transmitter detections recorded during the maneuver ( Figure 3) were used to create a series of location estimates for each fish detected using synthetic apertures [12] with the stipulation that the set of detections not exceed 90 s from the first to the last detection.…”

“…However, repeatedly locating multiple fish over a vast area remains a major challenge. In previous papers, we have discussed the development of payload control software [22] and its utility for mapping the location of multiple targets (reference transmitters at known locations and depths) during a single mission [23]. Here, we examine the use of AUV-based payload control to synoptically map the movements of a number of highly mobile marine fish.Chinook salmon (Oncorhynchus tshawytscha) are a wide-ranging anadromous species that spend several years in the marine environment before returning to coastal rivers throughout the northern Pacific Rim to spawn.…”