Seaworthiness through intelligent trajectory control
Department of Mechanical Engineering-Engineering Mechanics, Great Lakes Research Center
Navigation of autonomous surface vessels, less than 20 m in length, in large sea states is difficult and often precludes successful completion of the assigned mission or, in the worst case, survivability. Operation in high seas requires sensing of the local wave environment and determining a vessel trajectory that maximizes survivability based on knowledge of the vessel response functions and prediction of the incident wave field forward in time. To achieve this objective, new technologies are being developed and tested in full scale at the Marine Autonomy Research Site (MARS), located in central Lake Superior and operated by Michigan Technological University. In this initial set of experiments, a skilled human operator was used as a surrogate for an envisioned wave-adaptive autonomous control system. The test vehicle is a fully instrumented personal water-craft, operated by a U.S. Coast Guard-trained surf-boat operator in moderate sea states with Froude number (Fr) = 1.0 through a course consisting of up-wave, cross-wave, and down-wave legs. Results dramatically document that the wave-dodging maneuvers employed are designed to minimize vessel pitch (preserve propulsor and rudder control) while allowing increased vessel roll. Comparisons of the straight line with wave-dodging circuits during constant sea state conditions show that vehicle roll is at times twice greater in wave-dodging runs while vehicle pitch averages half to one third of that in the straight-line course. These data suggest that optimum paths do exist through steep, evolving incident wave fields and these optimum paths can produce significant improvements in vessel survivability.
Marine Technology Society Journal
Burns, J. W.,
Seaworthiness through intelligent trajectory control.
Marine Technology Society Journal,
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