Automatic Prevention of the Vessel’s Parametric Rolling on the Wave

Abstract

Parametric resonance is one of the most dangerous phenomena that occurs during a storm. In the event of a parametric resonance, an undamaged and properly loaded vessel can capsize within seconds. The essence of parametric resonance is to change the parameters of the vessel as an oscillating system. In this case, the coefficients of the differential equations of the vessel model become functions of time. Parametric oscillations are observed at a certain ratio between the frequency of the external influence and the frequency of the system's own oscillations. Parametric resonance in the roll channel is especially dangerous, which leads to a sharp increase in the amplitude of the vessel's rolling, water entering the deck and inside the vessel's hull, loss of stability and possible capsizing. The existing methods of storming are not effective enough, which is due to the use of visual methods for estimating the parameters of turbulence and manual graphic constructions, significant time delays between obtaining data for calculation and determining safe parameters of motion, the lack of constant measurement of turbulence parameters and refinement of safe motion parameters, the difficulty of selecting the dominant factor from the system dangerous factors, intuitive assessment of the level of danger. The authors have developed a method of automatic avoidance of parametric resonance, which differs from existing methods in that it automates the processes of measurement and information processing, reduces delays in decision-making, reduces the influence of the human factor on control processes, reduces crew fatigue, reduces the risks of losing the vessel and cargo, and in general increases the navigation safety. The developed method can be used for both manual and automatic control. In the manual control mode, the shipmaster has the opportunity to use automatically measured information and the results of its processing - visualization of parametric resonance areas and the position of the phase point for making management decisions. In the automatic control mode, the system itself calculates and implements safe movement parameters, and the shipmaster only observes its operation. The obtained results are reproducible and can be used to develop the functionality of automated systems and/or automatic parametric resonance avoidance modules.