海流干扰下海洋观测平台动力定位

Dynamic Positioning of Ocean Observation Platform under Current Disturbance

针对小型海洋观测平台,考虑其特殊的回转体形状,建立海流干扰下的运动学模型,针对螺旋桨的环形布置形式制订相应的推力分配方案.通过搭建半物理仿真平台,模拟平台在海流大小不同且方向相同、以及海流大小相同且方向不同时的动力定位过程,结果表明:平台可在海流干扰下完成动力定位且启动快速、定位准确、控制稳定性好.最后通过设计水池试验验证海洋观测平台在静水和海流干扰下的位置控制和艏向控制性能,结果显示海洋观测平台能在期望精度内完成动力定位.发现平台对转艏力矩较为敏感,因平台为回转体形状,在单独控制艏向时,只需较小的推力即可完成定位并且不会对位置控制产生明显的影响;而在进行位置控制时,因为海流和形状的影响,平台需要输出较大的推力.后者情况下,推进器一旦出现推力输出不协调,产生的附加转艏力矩将会对艏向控制产生不可忽视的影响.

Firstly,the kinematic model under the current disturbance is established considering the special rotating-body shape of the small ocean observation platform.And a corresponding thrust distribution scheme is established for the annularly arranged propellers.After the construction of semi-physical simulation platform,the dynamic positioning process of the platform is simulated when the current magnitudes are different while the directions are the same,and when the current magnitudes are the same while the directions are different.The results show that the dynamic positioning of the platform can be completed under the current disturbance,and with a fast onset,an accurate positioning and a good control stability.Finally,the performances of position control and bow control are verified through pool tests designed for the ocean observation platform both in the static water and under the current disturbance.The results show that the ocean observation platform can complete the dynamic positioning with the expected precision.It is also found that the platform is more sensitive to the turning moment.In a separated bow control,the positioning can be achieved with only a small thrust,without any significant impact on the position control,because the platform is in a shape of a rotor.While in a position control,the platform needs to output a larger thrust because of the impact of the current and the shape.And in the latter case,once the propellers output the thrusts that aren't coordinated,the resulting additional turning moment will significantly affect the bow control.