基于船舶水动力的六自由度a&ω运动参数发生器

A six-degree-of-freedom a&ω motion parameter generator based on ship hydrodynamics

针对传统轨迹发生器生成的轨迹和运动参数不符合实船特性问题,依据分离式结构模型六自由度船舶运动方程,分析不同运动状态的船体、桨、舵的水动力和力矩,推导静水条件下六自由度线加速度和角速度(a&ω)模型;提出以档位固联转速建立纵向线加速度的二阶模型,用二阶系统的阻尼比和自然频率表示档位切换时船舶的加、减速性能;采取极大似然估计的递推算法辨识模型中的未知参数;基于某船的实测数据,验证该运动参数发生器的有效性,并评估仿真准确度。仿真结果表明,该发生器能够生成线加速度、角速度、姿态、速度、位置共计15维运动参数,且各运动参数的准确度在95%以上。

Aiming at the problem that the trajectory and motion parameters generated by the traditional trajectory generator do not conform to the characteristics of the real ship,the hydrodynamic force and moment of the hull,propeller and rudder under different motion states are analyzed based on the separate structural model six-degree-of-freedom ship motion equation,and the six-degree-of-freedom linear acceleration and angular velocity(a&ω)model in static water condition is deduced.A second-order model of longitudinal linear acceleration is established based on the fixed speed of the gear,and the damping ratio and natural frequency of the second-order system are used to represent the acceleration and deceleration performance of the ship when the gear is switched.By adopting the recursive algorithm of maximum likelihood estimation,the unknown parameters in the model could be identified.Based on the measured data of a certain ship,the validity of the motion parameter generator is verified,and the simulation similarity is evaluated.The simulation results show that the generator can generate a total of 15-dimensional motion parameters such as linear acceleration,angular velocity,attitude,velocity and position,and the similarity of each motion parameter is more than 95%.