Developing an Autonomous Tracking System for the Atlantic Salmon
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- Institutt for marin teknikk 
This thesis presents an autonomous fish tracking system for a tagged Atlantic Salmon usingfour unmanned surface vehicles equipped with acoustic receivers. The system can beused to monitor both hatchery farmed and wild Atlantic salmon in an open ocean environment,and scientists can use the data to develop a better understanding of the speciesand the way it interacts with its environment. Error sources associated with the purposedsystem are presented. A target localization method based on the principle of time differenceof arrival positioning (multilateration), i.e an extended Kalman filter using acousticdata, is implemented and tested in a unified navigation environment (DUNE). The resultsreveal successful real-time localization of a target fish in a simulation located in the Trondheimsfjord. The hardware implementations presented in this thesis involves the integrationof a GPS-receiver, CAN-controller, motor controller and Torqeedo thrusters with a singleboard computer. Thrust commands and thruster response is successfully tested at NTNUGløshaugen, Trondheim, Norway.This thesis examines how important control system components of a fish tracking systemcan be developed to optimize system performance. A conceptual control system withobjectives of keeping receivers within transmission range while minimizing geometric dilutionof precision (GDOP), travel distance and need for inter-vehicle communication, ispresented. A conceptual formation controller unifies these system objectives in a singlealgorithm, and positions USVs in circular and circle-arc shaped formations depending onwhether the target is located within a restricted area or in the open ocean. The need forinter-vehicle communication is significantly reduced by allowing vessels to operate withindependent guidance systems. Positioning models for a cable-connected and fixed acousticreceiver configuration are developed with the purpose of accurately determining theirposition relative to a GPS aboard the vessel, while being subject to hydrodynamic forces.