深水半潜式锚泊定位系统控制策略及半物理仿真研究

发布时间：2018-01-16 21:07

本文关键词：深水半潜式锚泊定位系统控制策略及半物理仿真研究　出处：《哈尔滨工程大学》2014年博士论文　论文类型：学位论文

【摘要】：受风、浪、流等海洋环境干扰影响,半潜式平台不可避免地会产生六自由度摇荡运动,其中半潜式平台对水平方向的纵荡、横荡及艏摇运动不具有回复力,导致平台逐渐偏离平衡位置,进而威胁到半潜式平台的工作及安全性能。因此,平台定位系统的性能至关重要。锚泊定位与动力定位是迄今应用最广泛的定位系统,然而锚泊定位系统定位精度较低,动力定位系统经济性差,本文提出一种具有锚链切换控制的锚泊自动定位系统。该系统在保证平台的定位精度的基础上,降低了系统的总体成本,同时兼顾了锚链张力场的均匀分布,避免了因张力分配不均而引起锚链断裂的安全隐患,提高了定位系统的安全性。为研究锚泊自动定位半潜式平台的动力学特性,本文首先对平台的低频运动模型进行分析,为简化控制系统的设计及便于对被控对象的分析,将系统方程在低速状态下线性化,建立具有状态空间形式的平台低频运动方程。锚泊阻尼直接影响对半潜式平台及锚泊系统的运动响应预测的准确性,采用准静态分析方法来估算锚泊阻尼,并在作业平台运动方程的阻尼矩阵中加入计算得到的阻尼系数以更准确地计算平台的运动响应。分析半潜式平台所受海洋扰动性质,建立海风、海流、一阶波浪力及二阶波浪力干扰模型,并针对目标平台进行数值仿真以确定不同海清下平台所承受的海洋扰动力、力矩。阐述锚链动力分析的必要性,利用忽略抗弯刚度的弹性杆理论建立锚链的运动模型。弹性杆理论考虑了非线性因素的作用,推导过程严密。由于推导出的锚链运动控制方程为非线性微分方程,很难对其进行解析求解,因此采用有限元法将上述微分方程转换为弱形式,并采用数值积分方法对方程进行求解,用以分析锚链的动力特性。介绍了几种常用的数值积分方法,在分析各方法的优缺点的基础上,采用具有二阶精度、可控数值阻尼及无条件稳定性质的改进的广义α算法对锚链进行动力分析。进一步,采用间接时域法对平台与锚泊系统进行耦合分析,首先利用三维势流理论,在频域内得出半潜式平台的水动力参数,再通过频域时域转换将水动力参数变换到时域内建立时域耦合方程,求解平台及锚链的运动响应。分析半潜式平台锚泊自动定位系统特征,针对其具有输入时滞及不确定性的特点,说明LQR控制的局限性。结合线性矩阵不等式理论,鲁棒控制算法及李雅普诺夫稳定性理论,分别设计了具有区间输入时滞的H∞控制策略及保性能控制策略来产生抵抗环境扰动的控制合力(力矩)。具有区间输入时滞的H∞控制策略考虑了时滞下界不为零的情况,在Lyapunov函数的构造过程中,亦包含了时滞下界信息;在保性能控制策略的设计过程中,将具有输入时滞的保性能控制扩展到基于误差向量的形式以实现平台的定点定位。所设计的两种控制器从不同的侧重角度解决了由于水动力参数的不确定而引起的模型不确定性及由于锚链切换所导致的输入时滞问题。在保证平台目标位置的基础上优化锚链的张力分布,结合锚泊系统模型,通过定义目标函数为各锚链张力差的平方和最小来实现张力的均匀分布,而目标平台的位置则由约束条件来满足。基于Memetic思想,将具有较强全局搜索能力的遗传算法与具有较强局部搜索能力的改进模拟退火算法相结合,设计了混合优化算法将平台定位到期望位置所需的控制合力(力矩)均匀地分配给12条锚链,保证锚链张力场的均衡分布,并将优化值作为锚链切换的阈值。最后,进行半潜式平台锚泊自动定位系统的半物理仿真实验研究,实验结果显示,所设计的定位方案合理,控制策略性能良好。
[Abstract]:By the wind, wave, flow disturbances such as marine environmental impact, semi submersible platform will inevitably have six degrees of freedom motions, the semi submersible platform on the horizontal direction of the surge, sway and yaw motion with restoring force, leading to the platform gradually deviate from the equilibrium position, and thus a threat to safety and performance submersible platform. Therefore, performance of platform positioning system. Mooring positioning and dynamic positioning is by far the most widely used positioning system, but the system positioning accuracy of mooring positioning is low, economic dynamic positioning system, this paper proposes a switching control cable with automatic mooring positioning system. The system guarantee the positioning the accuracy of platform, reducing the overall cost of the system, taking into account the uniform distribution of cable tension field, avoid tension caused by uneven distribution of chain breaking security risks, improve Safety positioning system. For the dynamic characteristics of the automatic positioning of semi submersible platform mooring research, firstly, the low frequency motion model of the platform is analyzed, to simplify the design of control system and is convenient for the analysis of the controlled object, the system equation is linearized at low speed state, establish the platform frequency equations of motion with the form of state space. Mooring damping directly affects the accuracy of predicting the response of semi submersible platform and its mooring system, using the static analysis method to estimate the mooring damping, response and damping matrix in the motion equation of the working platform added damping coefficient calculated by the more accurate calculation of the motion of the platform. Analysis of semi submersible platform by sea disturbance the establishment of nature, wind, ocean currents, the first-order wave force and two order wave force interference model, and according to the target platform for the numerical simulation to determine the different level of Hai Qing Marine disturbance, Taiwan the moment. Explaining the necessity of dynamic analysis, the motion model of elastic rod theory ignores the bending stiffness of the anchor chain. The theory of elastic rod established considering nonlinear factors, rigorous derivation. The deduced chain motion control equation is a nonlinear differential equation, it is difficult to the analytical solution, so the finite element method is used to convert the differential equations into weak form, and the numerical integration method to solve the equations for dynamic analysis of anchor chain. This paper introduces some commonly used numerical integration methods, based on the analysis of advantages and disadvantages of various methods, with two order accuracy improvement the generalized algorithm is unconditionally stable and controllable numerical damping properties of the dynamic analysis of the anchor chain. Further, the coupling analysis of platform and mooring system using the indirect method in time domain, first With the three dimensional potential flow theory, the hydrodynamic parameters of semi submersible platform in the frequency domain, and then through the frequency domain conversion will establish a time-domain coupled equations of hydrodynamic parameters and transform domain response platform and chain movement. Analysis of mooring automatic positioning system of semi submersible platform according to its characteristics, with input delay and characteristics uncertainty, illustrate the limitations of LQR control. Combined with the theory of linear matrix inequalities, a robust control algorithm and Lyapunov stability theory, are designed with input delay interval H control strategy and the guaranteed performance control strategies to generate resistance control environmental perturbation force (torque). H control strategy with input delay interval considering the lower bound of delay is not zero, in the construction process of the Lyapunov function, also contains information on the lower bound of delay; guaranteed cost control strategy design process, will be out With input delay guaranteed performance control extended to the designated location error vector form based on the platform. In order to achieve the two kinds of controller designed to solve due to uncertain hydrodynamic parameters of model uncertainty and input delay due to problems caused by the chain switching from different angles. In order to ensure the focus on optimizing the distribution of cable tension based on the position of the target platform, combined with the mooring system model, by defining the objective function for the cable tension difference square and minimum tension to achieve uniform distribution, and the location of the target platform is to satisfy the constraint conditions. Based on the idea of Memetic, combining genetic algorithm with strong global searching ability and has improved the strong local search ability of the simulated annealing algorithm, a hybrid optimization algorithm to design the control platform position to the desired position required force (torque) evenly divided 12 ration chain, to ensure a balanced distribution of cable tension field, and the value chain optimization as the switching threshold. Finally, the simulation experiment of semi physical mooring automatic positioning system of semi submersible platform, the experimental results show that the localization scheme design is reasonable, the control strategy has good performance.

【学位授予单位】：哈尔滨工程大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：P751

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