Custom Autonomous Watercraft with Improved Transect Heading Accuracy to Ascertain Higher Quality Measurements with the Sontek River Surveyor S5

Bathymetric data to build hydrological and hydraulic models are often scarce or unavailable. Submerged topographic surveys collected using semi-autonomous systems provide a reliable, cost-effective, and risk-averse method of conducting a variety of surveys and sampling in the marine environment. Data obtained by these systems can be used for building the computational domain, initial and boundary conditions, model result validation, and reference for three-dimensional flow structures. Dual thruster autonomous boat designs utilizing differential thrust for steering, sacrifice their heading accuracy while preforming the transect measurement.

To address this challenge, the Center for Autonomous Sensing and Sampling (CASS) at the University of Oklahoma has designed and built a custom autonomous watercraft with increased transect heading accuracy to ascertain higher quality measurements with the Sontek River Surveyor S5. This new design is a radially symmetric light-weight aluminum X style frame supported by a commercially available 44-inch inflatable inner tube rated to buoyantly support an all-up weight of 240 lbs. Its four Blue Robotics T200 thrusters are operated by a Pixhawk 2 autopilot system, running Ardupilot's Rover OmniX firmware. As an additional safety feature, the watercraft frame provides enough buoyancy and stability for a return to launch maneuver in case of a failure of its inner tube. This design can swiftly move Omni-directionally on the water due to the inclined angle of its four thrusters giving it the unique ability to maintain heading irrespective of the direction it is traveling. This feature maintains the measurement reference of the Sontek River Surveyor S5, eliminating possible sampling artifacts produce by heading changes, common in dual thruster design.