Abstract

In general, tugboats are used to convey many kinds of surface vessels, including unactuated vessels, such as barge ships and offshore structures. This requires an adequate model for tugboat operation to precisely take into account surge, sway, and yaw motions. We present an optimization method of tugboat operation for conveying a large surface vessel in the shipyard. An optimization problem that includes the interactions between the vessel and the tugboats is mathematically formulated. The procedure to solve this problem is composed of three steps. The desired control input, which should act on the vessel to track the desired path in the presence of environmental disturbances, is calculated every control interval. Second, the optimization problem is solved by using an optimization algorithm to find the thrust force and tug force direction for each tugboat. Finally, based on the three-degrees of freedom (DOF) horizontal model, the position and velocity of the vessel in the next step are calculated. There are three advantages to this study. First, the proposed method considers the thrust force and the direction of the tugboats at the same time, and the number of tugboats can also be changed. Second, it is possible to control the tugboats through realistic time intervals. Finally, the practical external force is considered in the application. The proposed method is applied to the conveying of a mega floating crane, one of the large surface vessels, in various environmental conditions, such as waves, winds, and currents, and the applicability of the method was evaluated.

中文翻译：

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大型水面船拖船作业优化模型

摘要

通常，拖船用于输送多种水面船只，包括未操纵的船只，例如驳船和近海结构。这需要用于拖船操作的适当模型，以精确地考虑喘振，摇摆和偏航运动。我们提出了一种用于在船坞中运输大型水面船的拖船作业的优化方法。在数学上制定了一个优化问题，其中包括船只与拖船之间的相互作用。解决此问题的过程包括三个步骤。每个控制间隔都会计算所需的控制输入，该输入应作用于船舶上，以在存在环境干扰的情况下跟踪所需的路径。第二，通过使用优化算法找到每个拖船的推力和拖船方向来解决优化问题。最后，根据三自由度（DOF）水平模型，计算下一步中船只的位置和速度。这项研究有三个优点。首先，提出的方法同时考虑了拖船的推力和方向，拖船的数量也可以改变。第二，可以通过现实的时间间隔来控制拖船。最后，在应用中考虑了实际的外力。所提出的方法适用于大型浮船之一的大型浮式起重机在各种环境条件下的运输，例如波浪，风和洋流，