Differences

This shows you the differences between two versions of the page.

--- intro [2020/08/31 11:39] – nikolal
+++ intro [2022/09/19 11:34] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
 ====== Introduction ======
+The goal of the project, is to be able to perform persistent tracking of acoustic fish tags through combining sensor readings from multiple vessels through multilateration. To further break this down, a scenario of the type of mission is given below.
-===== Fish Tracking Scenario =====
+^ # ^ Mission Phase ^ Description ^
+| 1 | Transport | Bring the equipment to the deployment area. |
+| 2 | Deployment | Assemble and prepare the vessel. Ensure supporting systems (Server/Operator console) are running. Launch vessels. |
+| 3 | Travel to search area | Vessels travel from deployment area to search area. |
+| 4 | Collaborative search | Search area is divided between vessels. Ends after first tag detection. If first search yields no result, perform predetermined action, like searching again or extending search area. |
+| 5 | First tag contact | First contact with acoustic tag. The detecting vessel waits or tries single vessel tag positioning. Other vessels congregate to its vicinity, entering formation. |
+| 6 | All vessel tag contact | Enter tag formation to commence collaborative fish tracking. |
+| 7 | Collaborative fish tracking | Keep formation around tag to estimate its position. |
+| 8 | Tracking end | Mission finished or battery level low – wait for pickup or return to predetermined point (like deployment point). |
+| 9 | Berthing/ Dismantling equipment | Removing the vessel from the water.|
+| 10 | Transport | Pack up equipment and leave deployment area |
+===== Collaborative Fish Tracking =====
+{{ :scenario.png?400|}}
+A visual representation of the most important phase of the scenario, the fish tracking,
+is shown in the figure. Here, the three Fish Otters have gained contact with a tagged fish,
+and is using multilateration to estimate its position. Based on the estimate, decisions are
+then made regarding the next position of the formation. The formation also has to try to
+minimize GDOP, while at the same time avoiding surrounding hazards and reducing the
+thruster usage. Reducing motor usage is beneficial because it conserves the stored energy
+and reduces noise in the medium (water). Increased noise makes it harder for the acoustic
+receiver to discern tag transmissions and may also influence the fish behavior.
+The communication between the operator and the vessels, can, as shown in the figure
+go through two channels: the public cellular network, and the private Ubiquiti AirMax
+network. Either one, or both at once is to be used, with the expectation that bandwidth
+and increased network control will be benefits of the AirMax channel, while range is the
+benefit of the cellular communications.
+Positioning of the vessels is based on GNSS systems, which also is a multilateration
+system. The GNSS can be used as an inverted analogy for the fish tracking performed by
+the Otters. In the GNSS, the satellites transmit signals, with the Otters receiving them.
+In the fish tracking scenario, the Otters have the same role as the satellites, but instead
+receives the message sent from the acoustic tag for surveillance purposes.
+===== The NTNU Fish Otter =====
+The target vessel for the system is the NTNU Fish Otter, with its main entities as shown in the diagram. Further details on the vessel is given in their own sections, available from the menu.
+{{ :otteroverallhw.png?600 |}}
-The Otter ASV is a 2 meters long catamaran propelled by two electrical fixed thrusters. This means that steering has to be done through differential thrust by the controller.
-{{ :otter_w_parts_descriptions.png?600 |}}
-===== The control box =====
-The control box is based around a Raspberry Pi 4 with 4GB of RAM. Connected through it's GPIO pins is a [[https://www.sfeerralabs.cc/product/strato-pi-can-board/|Strato Pi CAN]] board that provides a robust power supply in addition to multiple communications interfaces and an independent hardware watchdog. A CAN network connects the Raspberry Pi to the Torqeedo Interface card. Thus it has access to both power channel and motor control. There is a passive PoE injector providing power for the external BulletAC IP67. It also contains a SLIM interface board that synchronizes and reads the RS-485 serial communication from the TBR-700 -/RT hydrophone.
-{{ :control_box.png |}}
-===== The thrusters =====
-The thrusters used by the Otter are two [[https://www.torqeedo.com/en/products/outboards/ultralight/ultralight-403/1404-00.html|Ultralight 403]] motors by Torqeedo. They can provide a maximum propulsive power of 180 W each, and would be the equivalent of 1HP each according to the manufacturer. It can do a maximum of 1200rpm at the propeller, and has a gear ration of 7:1.
-===== The batteries =====
-The batteries are of the shelf [[https://www.torqeedo.com/en/products/accessories/spare-batteries/battery-915-wh-ultralight-403/1417-00.html|Torqeedo batteries]] developed for use with their electrical outboard motors. The Otter can carry four of these batteries, for a total capacity of 3660Wh, or 124Ah. This provides the Otter with up to 20 hours of battery powered operation, depending on speed and payload(according to [[https://www.maritimerobotics.com/otter|Maritime Robotics]]).
-===== The hull =====
-Delivered by Maritime Robotics, the hull is designed to be light and portable. At 200cm length and 108cm width, transport and handling can become an issue, but the Otter solves this by being built in a highly modular way. According to the manufacturer, it's possible to disassemble it into parts of under 20Kg each, making it possible to move it by a single person.
-//Insert image of Otter hull here//