해양구조물을 위한 작업공간기반 환경력최소 위치유지 제어

Abstract

A nonlinear weather optimal positioning control algorithm is designed in the task space and its stability is examined using the Lyapunov stability concept. Conventional Dynamic Positioning (DP) systems for ships and offshore rigs are usually designed for station-keeping by specifying a desired position and a desired heading angle. In order to minimize fuel consumption, the ship should be oriented toward the direction of the mean environmental force due to winds, waves and currents acting through the center line of the vessel. Such condition results in a zero sway force and yaw moment which can significantly reduce the fuel consumption with reduced Nox/COx emissions. However, it is generally difficult to measure or estimate the direction of the mean environmental force with sufficient accuracy. Therefore, a weather optimal positioning control algorithm that does not require the estimation of the direction for mean environmental force is desirable. In this paper, a nonlinear weather optimal positioning control algorithm is discussed. In the control algorithm, the desired position is specified in the task space and the yaw motion is confined in null space. To guarantee the stability of the control algorithm, the controller is designed using the system dynamics of the vessel, and its stability is examined using the Laypunov stability theory. KRISO has developed several simulation tools to examine the control performancey designed for station-keeping by specifying a desired position and a desired heading angle. In order to minimize fuel consumption, the ship should be oriented toward the direction of the mean environmental force due to winds, waves and currents acting through the center line of the vessel. Such condition results in a zero sway force and yaw moment which can significantly reduce the fuel consumption with reduced Nox/COx emissions. However, it is generally difficult to measure or estimate the direction of the mean environmental force with sufficient accuracy. Therefore, a weather optimal positioning control algorithm that does not require the estimation of the direction for mean environmental force is desirable. In this paper, a nonlinear weather optimal positioning control algorithm is discussed. In the control algorithm, the desired position is specified in the task space and the yaw motion is confined in null space. To guarantee the stability of the control algorithm, the controller is designed using the system dynamics of the vessel, and its stability is examined using the Laypunov stability theory. KRISO has developed several simulation tools to examine the control performance