Seakeeping Characteristics of a Wave-Adaptive Modular Unmanned Surface Vehicle

Abstract

Sea-keeping characteristics of a wave-adaptive modular catamaran, developed by Marine Advanced Research Inc., is studied using at-sea experiments and dynamic modeling. The vehicle is based on the Proteus design and is supported by two inflatable pontoons with each pontoon attached to a center payload tray using an independent suspension system connected in such a way that the demi-hulls perform somewhat independent motions through a wave field. The suspension system is designed to isolate the center payload tray from the motions induced by waves incident on the demi-hulls. The vehicle is propelled by two water jets and is capable of achieving speeds of 8–15 knots. Accelerometers have been mounted on the pontoons and the center payload tray of the vehicle and field tests in the open ocean have been carried out to study sea-keeping properties of the vehicle. Heave and surge motions for the cases of following seas, beam seas and head seas have been recorded. In each case the center payload tray is found to experience attenuated heave accelerations compared with the two pontoon hulls. The reductions in surge and sway motion are, however, not evident. The associated spectra suggest that heaving motion of the center payload tray over a range of frequencies is attenuated by the suspension system. No attenuation is apparent in the surge and sway motions. The WAM-V dynamics is modeled as a three-body problem with the pontoons corresponding to bodies 1 and 2, and the central tray to body 3. Results of the analysis are compared with the sea trials.

Control of an Unmanned Surface Vehicle With Uncertain Displacement and Drag

“…In order to determine the accuracy of the mathematical model presented above and to determine the hydrodynamic coefficients in the added mass matrix (7), Coriolis matrix (8), and drag matrices (10), (11), the experimental zig-zag and acceleration data are overlaid with simulation results for matching motor input. The values of the hydrodynamic coefficients were manually adjusted until the simulation results qualitatively matched the experimental data.…”

“…The vessel structure consists of two inflatable pontoons, two motor pods, a payload tray, and two supporting arches. The WAM-V class of vehicles is designed to provide a stable platform that can mitigate the effects of waves [11], [16], [30].…”

“…To develop a surge speed controller, the surge equations of motion given by ( 3), ( 7)- (11), and (17) were reduced to:…”

“…To develop a heading controller, the yaw rate equations of motion given by (3), and ( 7)- (11) were simplified as:…”

Investigation of a Cabin Suspended and Articulated Rescue Vessel in Terms of Motion Reduction

“…In the actual use of rescue vessels, heave motion and roll motion have the greatest influence on the seakeeping performance, so the motions of the pontoons and roll motion are added to form the four-DOF model shown in Figure 4, based on the single-DOF model proposed by Manhar R. Dhanak [28]. k 1 and k 2 are the equivalent stiffness coefficients of the flexible pontoon and suspension system.…”