驻留型UUV锚泊系统运动建模与分析

Dynamic modeling and simulation of mooring system for an unmanned underwater vehicle

针对驻留型水下航行器(UUV)锚泊系统对水流作用的运动响应问题,依据欧拉-伯努利梁理论,建立了包括弯矩作用在内的锚链三维运动模型,并使用四元数代替欧拉角来描述锚链姿态,以消除某些特殊情况下因锚链姿态大幅度变动或个别欧拉角不确定性导致的运动方程奇异现象,然后通过适当的边界条件,将UUV、锚链和锚块的运动控制方程耦合起来,采用有限差分方法对系统耦合运动模型进行数值离散处理通过牛顿-拉夫逊方法迭代求解整个锚泊系统的运动响应。使用Hopland拖曳试验数据对模型进行实例对比验证。结果表明:这种建模方法可以取得良好的准确性与计算效率,在此基础上模拟仿真得到了周期变动水流作用下的UUV位置及姿态的响应情况为锚泊系统的正常工作提供理论依据。

To determine the kinematic performance of an unmanned underwater vehicle（ UUV） attached to a mooring line and lurking on the seabed,a three-dimensional cable mathematical model that considers the effects of bending moments was established based on the Euler-Bernoulli beam theory. In addition,a quaternion-based cable attitude model was adopted as a substitute for the traditional Euler-angle form to eliminate the singular behavior under some special circumstances,namely,a drastic change in cable attitude or the existence of some specific uncertain Euler angles. The governing equations of the UUV,cable,and anchor were integrated by using appropriate boundary conditions to obtain the translational and rotational motion equations of the mooring system. Thereafter,the mathematical model of the mooring system was discretized by using the finite difference method,and the Newton-Raphson iterative method was employed to solve the difference equations. Application data from Hopland＇s towing experiment were extracted to validate the mathematical model. The results show that the modeling algorithm is accurate and efficient. Then,the UUV＇s position deviation and attitude change were simulated in periodically changing current to provide a theoretical principle for maintaining its normal working state.