DEPTHX Autonomy Software: Design and Field Results

This paper describes the control, navigation, and mapping methods that were developed for a hovering autonomous underwater vehicle that explored flooded cenotes in Mexico as part of the DEPTHX project. The cenotes of Sistema Zacat́on in Tamaulipas, Mexico, are flooded sinkholes, exotic geological formations with unique water chemistry. The deepest, Zacat́on, is over 300m deep. None of the cenotes were mapped before this project. The goals of the DEPTHX project were to construct metrically accurate three-dimensional maps of the cenotes, and to collect environmental data, imagery, water samples, and core samples. The unknown depths of the cenotes, together with the challenging scientific mission, spurred the development of a robotic vehicle which autonomously (with no communications to the surface) built accurate 3D maps using sonar and collected a variety of scientific data, including core samples from the cenote walls. In this paper, we describe the design, implementation, and testing of the robot software, as well as the results from mapping four cenotes of Sistema Zacat́on.