Roll Stabilization by Passive Anti-Roll Tanks Using an Improved Model of the Tank-Liquid Motion

Abstract

Roll motion is an undesirable feature of the behavior of a ship in rough seas, and so it is natural to consider ways of reducing it. The most common devices for increasing roll damping are bilge keels. However, the effectiveness of keels is limited, and anti-roll tanks and fins are used when more control is required. Moreover, unlike keels, anti-roll tanks can be used when the ship is not underway. Our objective is to develop design procedures for passive tanks for roll reduction in rough seas. To this end, we develop an improved model of the passive tank-liquid motion in this paper. This tank consists of U-shaped tubes placed side by side along the length of the ship. The equations of six-degrees-of-motion (6DOF) that govern the tank-liquid are coupled with those that govern the 6DOF motion of the ship, and all of the equations are integrated simultaneously in the time domain using the Large Amplitude Motion Program (“LAMP”). LAMP is a three-dimensional time-domain simulation of the motion of ships in waves. The unstabilized and stabilized roll motions of a S60-70 ship with forward speed and beam waves have been analyzed. For high-amplitude waves, the variation of the roll angle with the encounter-wave frequency exhibits typical nonlinear phenomena: a shift in the resonance frequency, multi-valued responses, and jumps. The performance of passive tanks on a S60-70 ship with forward speed is investigated in an irregular sea with different encounter-wave directions. It is found that passive anti-roll tanks tuned in the nonlinear range are very effective in reducing the roll motion. The effect of the tank mass and distribution of tank tubes on the performance of the tank system is studied. Also, it is found that passive anti-roll tanks are very effective in reducing the roll motion in sea state five of a ship whose pitch frequency is nearly twice its roll frequency.

A roll-motion control system for a mobile-wheeled platform: a preliminary test platform for roll-motion control of ships

“…Thus, an auxiliary control input must be added to eliminate the effect of the unpredictable uncertainties. Unfortunately, the value of the uncertainties is difficult to obtain precisely in advance for practical applications (Zborowski and Taylan, 1989;Youssef et al, 2003;Nasrallah et al, 2007;Surendran et al, 2007;Perez and Goodwin, 2008;Marzouk and Nayfeh, 2009;Fang et al, 2010;Hassan and Parviz, 2010;Huang et al, 2010;Khaled and Chalhoub, 2011;Zhigang et al, 2011;Chaouch et al, 2012). A fuzzy inference mechanism and a sliding surface are combined to cope with this problem.…”

“…Active stabilizing systems are defined as the need of input energy in the form of a pump, hydraulic piston, or electric actuator. To this end, much research has been done to develop various approaches, such as tank stabilizer (Youssef et al, 2003;Marzouk and Nayfeh, 2009), gyroscopic stabilizer (Schlick, 1904), rudder stabilizer (Hasegawa et al, 2006;Kim et al, 2007) or fin stabilizer (Fang et al, 2010;Hassan and Parviz, 2010;Li et al, 2010;Jin et al, 2011;Zhigang et al, 2011) etc. The tank stabilizer depends on the pumping around the fluid to counteract the motion of the vessel.…”