Magnetic Methods for Underwater Localization and Navigation

Underwater robotics is a rapidly expanding field with many important applications. From exploration and maintenance of oil and gas installations, to search and rescue, to defense, robotic agents are desirable for efficiency and safety reasons. However, performing tasks with only one agent usually necessitates an increase in size and complexity, which in turn exacerbates the power requirements that can drastically reduce run times. Instead, this dissertation examines localization between a group of agents, so that they can cooperate and perform tasks. My work on this project focused on the practical implementation of underwater localization and navigation. For robotic agents to cooperate and efficiently work together, they must be able to efficiently locate each other and communicate. While many technologies have been employed for communication in underwater environments, they have drawbacks that we try to address through the use of magnetic induction (MI) communications. The first part of this dissertation focuses on implementing MI so different agents, with limited prior knowledge of the swarm, can find each other and communicate at short distances, where collision between agents is most probable. The theoretical basis and validation, as well as hardware design and implementation are covered. The use of magneto-statics to find ferrous objects underwater, such as pipes, is presented in the second part. This is important for inspection and maintenance tasks, as it can complement vision-based methods in finding objects in waters with low visibility or even partially covered by the ocean floor. Detection of ferrous structures is also a necessity to avoid collision when navigating around them.