动力定位船舶全回转推进器工作区优化

Workspace optimization of azimuth thrusters applied by dynamic positioning

[目的]为使动力定位全回转推进器及时响应外界环境力,避免推进器产生大范围旋转,实现动力定位控制的高精度,开展全回转推进器最佳工作区间研究。[方法]以安装有两个全回转推进器和一个侧向推进器的动力定位自航模型为研究对象,首先,分析当前推力分配奇异性优化指标存在的问题,在此基础上考虑推进器的推力限制,并采用遍历推进器推力及方位角的方法,建立轴向最大能力矩阵;然后,根据外界环境力大小及变化,计算得到各轴向的最低性能要求,结合禁止角,确定推进器在不同外界环境下的最佳工作区间,获得新的推力分配逻辑框架;最后,基于传统奇异性指标与最佳工作区间的动力定位船模,分别开展定点定位试验。[结果]结果表明,所提方法能够克服奇异性指标存在的不足,实现推进器方位角在50°范围内变化,定点定位达到0.1 m半径位置和0.5°艏向的控制精度。[结论]所述方法可替代奇异性指标,满足船模动力定位试验要求,具备一定的工程实用价值。

[Objectives]In order to make the dynamic positioning of azimuth thrusters respond to external environmental forces in time,avoid the large-scale rotation of the thrusters and achieve high precision dynamic fixed-point positioning control,research on the optimal workspace of azimuth thrusters is carried out.[Methods]Taking the dynamic positioning self-driven model with two azimuth thrusters and a lateral thruster as the research object,the problem of the current thrust allocation singularity optimization index is analyzed,and the thrust limits of the thrusters are further considered.The method of traversing the thrust and azimuth of the thruster to establish the axial maximum capability matrix is applied.According to the external environmental force mean and variance,the minimum axial capability requirements are calculated,the optimal workspaces of the thrusters in different external environments are determined by combining the prohibition angle,and a new thrust allocation logic framework is proposed.The fixed-point positioning experiment of a dynamic positioning ship model based on the traditional singularity index and optimal workspace is carried out.[Results]The experimental results show that the proposed method can overcome the shortcomings of the previous singularity index and achieve control accuracy of 0.1 m radius position and 0.5 degree direction control accuracy under the propeller azimuth within the range of fifty degrees.[Conclusions]This method can replace the singularity index;it also satisfies the requirements of the ship model dynamic positioning experiment and has certain practical engineering value.