| dc.description.abstract | In the modern world autonomous systems are becoming ubiquitous - a development driven forth by symbiotic advances in multiple areas of technology as well as the omnipresent desire to cut cost and eliminate risk to humans as well as equipment. These points are especially pertinent to militaries and armed forces around the world, as even the slightest advantage can mean all the difference on the field of battle. One area particularly prone to risk is that of mine clearance, both on land and at sea. Mines are cheap, prolific and even the threat of mines in an area is enough to impose an extra moment to be considered into the decision-making loop of a military commander. It is thus of the utmost importance to be able to eliminate this threat as quickly as possible without the the level of risk involved exceeding acceptable limits. The idea of using unmanned systems to this end is not new, but it is not until the past two decades it has really been conceivable to put truly unmanned, autonomous systems into reality. The Royal Norwegian Navy (RNoN) currently operates specialized classes of ships with dedicated crew compliments responsible for the tasks of mine hunting- and sweeping respectively. These are however aging and has been slated for decommissioning and thus their mission-portfolio will need to be handled in other ways. In the envisioned future concept, mine hunting-and sweeping is done by the use of autonomous craft in a bid to eliminate risk to humans, reduce cost and shorten Mine Countermeasure (MCM) operation timelines. The intention is to employ several unmanned agents working in concert, where Unmanned Underwater Vehicles (UUV) hunt - i.e locate and identify potential threats whereupon Unmanned Surface Vehicles (USV) move in and perform the sweep, neutralizing the identified object. This is where the USV Odin comes in. The RNoN intends to deploy Odin in an MCM capacity within the year 2028. The key idea is to utilize Odin to render the execution of mine-sweeping operations autonomous. In the context of marine control systems this will involve both single ship towing operations as well as using two USVs as dual towing vessels moving in formation for the more demanding towing operations such as for instance closed-loop magnetic influence sweeps. The purpose of this project thesis has been to evaluate the feasibility of conducting this next generation mine-sweeping concept. To this end, an extensive literature review has been conducted into several topics including amongst others autonomous marine vehicles, formation control and towing. This report encompasses and extensive overview of the mathematical model of the Odin, which is an 11m long Rigid-hull Inflatable Boat (RHiB) currently serving as a technology demonstrator and test-platform at the Norwegian Defense Research Establishment (FFI). In order to model and simulate the concepts, the missions are dissected into its constituent components as seen by a control systems designers perspective, where the first problem is that of getting one USV to follow a predetermined path - to which end a line-of-sight path-following controller is demonstrated in the presence of ocean currents. Here, the relative angle between the vessels headingψand the angle angle between the LOS vector and the pre-described path is the set-point for a heading autopilot in turn forcing the craft to track the path. Thereafter the concept of single-ship tow is expatiated upon before finally the ambition is getting two USVs into a formation, following a path with robustness to environmental disturbances. Relevant theory is elaborated and ultimately proof of concepts are offered using pre-established designs. The simulations and demonstrations show that the concepts are indeed feasible, but that there area lot of various elements that should go into a complete system before it will be fully operational.Through the lens of the projects overall ambition it is the perspective of the author that the project has been a success. | en |
