Development of a Control Algorithm for Active Control of Rolling Motion of a Ship by Gyro-Stabilizer

Abstract

In this study, a new algorithm for an active gyro-stabilizer was developed and applied to a ship model. The active gyro-stabilizer consists of a gyro sensor that measures the angular velocity of the rolling motion of a ship, a controller that realizes the active control algorithm, and an actuator that is connected to the precession axis. The new control algorithm receives the rolling rate of the ship, and outputs the desired precession angle. A suitable actuator for this kind of mission could be a servomotor. First, a theoretical model with a passive gyro-stabilizer was investigated to show the working mechanism of the gyro-stabilizer. It was found that the passive gyro-stabilizer works as additional stiffness. Based on the equations of motion of the ship with a gyro-stabilizer, a new control strategy for an active gyro-stabilizer was developed. It was found theoretically that instead of increasing stiffness, the damping of the rolling motion of the ship could be increased by tuning the filter frequency of the control algorithm to the rolling frequency. Both numerical and experimental results showed that the proposed control algorithm is valid and cost-effective, because it does not require a high-speed and heavy spinning wheel.

Keywords: Gyro-stabilizer, Active control algorithm, active roll damping.