Design and validation of a micro-AUV for 3-D sampling of coherent ocean features

The ocean, as vast as it is complex, has a plethora of phenomena that are of legitimate scientific interest, e.g., ocean fronts and Lagrangian Coherent Structures. These coherent ocean features occur from tidal mixing and ocean circulation, and are generally characterized with narrow bands of locally intensive physical gradients with enhanced circulation, biological productivity, and optimal transport phenomena. Spatial extents of these phenomena can be on the order of 10´s of km², and episodic events can last from hours to weeks. These ocean features are 3-dimensional, where to date, most research has focused on examining only their 2-dimensional expression. These coherent features cannot be thoroughly studied through traditional sampling involving random and/or discrete sampling approaches, moreover it is not cost-effective to validate new sampling methodologies in the field. Additionally, operating a single robotic platform in the ocean is hard, and coordinating a team of robots presents challenges in communication on top of dealing with navigation and complex ocean dynamics. To this end, in this paper we present the development and validation of a micro Autonomous Underwater Vehicle for deployment in a laboratory testing tank able to accurately simulate large-scale ocean dynamics. The goal is to provide a laboratory-scale, underwater vehicle for validating and testing algorithms and strategies to sample the 3-dimensional structure that exists in coherent ocean features, e.g., ocean fronts, eddys and Lagrangian Coherent Structures, for the purpose of developing better physical and biological models to aid autonomous ocean research. We provide a detailed description of the vehicle and present multiple results from lab experiments.