自动光学检测在系泊链测量中的应用

针对系泊链拉伸试验中各长度参数测量要求,提出了利用自动光学检测技术对系泊链进行测量的具体方案。设计了简单实用的图像拼接方案,给出了系泊链长度测量的计算公式。对光学测量中的镜头畸变误差进行了分析并提出了校正方法。实验证明该方案达到了如下测量精度:单环长度的0.64%、单环宽度的1.08%、铁链直径的1.66%和五环长度的0.46%。     

基于神经网络的系泊系统主动式截断试验仿真

系泊系统主动式截断试验技术对缆索数值模型的求解速度有着较高的要求,而基于集中质量模型或有限元模型的缆索数值模型在计算时需要在每个时间步内迭代求解,因此求解速度缓慢;为解决此问题,采用神经网络辨识得到缆索上端点与截断点运动的时域等价近似模型;该等价模型在每个时间步内无需迭代求解,因此求解速度快于传统的缆索数值模型;同时利用商软OrcaFlex以及Matlab搭建了系泊系统主动式截断试验的仿真平台,将离线辨识得到的神经网络模型代替集中质量模型对缆索截断点运动进行求解;通过对比截断水深以及全水深下张力以及运动结果,说明了神经网络模型代替传统数值模型进行截断点运动计算的可行性。     

固定码头船舶系泊自动化系统初探

传统的船舶停靠码头都是通过缆绳系泊方式实现的,缆绳系泊固定码头受潮差影响比较大,需要通过派遣值班人员来收放缆绳以保证船舶的稳定,增加了值班人员的工作强度。基于船舶系泊在固定码头的复杂因素而导致的各种问题,设计一套由智能微电脑(单片机)进行检测和监控的自动化系泊系统。通过此系统可以对船舶在码头系泊受到影响时完成自动化控制,节省人力资源并且可以对船舶进行精准控制,根据船舶系泊在码头受到潮差、风、浪、流等因素影响会发生升沉、回转、纵移、横移的现象,对单片机进行编程使其可以通过判断船舶的具体状态,从而控制电机的正转反转来对缆绳进行收放,最终完成对船舶在码头系泊状态下的全程自动化控制。     

水上飞机运动及系泊性能计算方法研究

波浪环境下水上飞机的系泊性能直接影响飞机的使用效能和寿命。针对水上飞机系泊性能预报问题,采用海洋工程领域多点系泊方式对水上飞机进行定位。基于势流理论,考虑系泊线与飞机间的水动力耦合,以及系泊线的非线性特性,对系泊状态下的水上飞机开展频域和时域数值模拟。对规则波和不规则波中的飞机运动响应和系泊线张力进行时历统计。结果表明,在迎浪状态下,飞机首部系泊线张力最大,同时在三级海况条件下,各系泊线的张力最大值均小于破断张力,系泊系统处安全状态。这一结果可为水上飞机系泊系统的设计与安全评估提供参考。     

多浮筒系泊系统计算软件设计

设计一种计算多浮筒系泊系统的迭代算法。根据海洋工程应用特点,基于C语言设计多浮筒系泊系统悬链线姿态曲线计算软件。以Armadillo线性代数库等为基础搭建开发环境,设计软件结构,进行系统模块功能分配。该软件具有人机界面友好、算法易收敛、计算速度快、输入输出设定方便等优点。实验验证了软件计算的准确性。     

基于力/位混合算法的7自由度机械臂精细操控方法

为了使冗余机械臂在具有良好的自治性和灵活性的同时保证末端的执行精度,提出一种基于力/位混合控制的冗余机械臂精细控制方法.通过建立准确的运动学模型,分析机械臂系统的运动特性,利用固定角度与梯度下降相结合的方法求动力学逆解.在对机械臂的力/位混合控制律建模的基础上,利用位置控制和力控制对机械臂末端的运动轨迹进行规划.针对受环境约束的机械臂的控制问题,提出冗余自由度机械臂的适从坐标系建立方法,使得末端执行器能够在任意曲面完成作业任务.在仿真分析和实验中,令机械臂末端跟随任意设定的曲线轨迹到达给定点.通过多次测量得出,力精度误差小于2%,并且在保证作用力方向精确的条件下,机械臂末端轨迹的偏离值小于5%.结果表明,所设计的力/位混合控制方法对7自由度机械臂控制精度效果良好.     

基于改进ACPSO的等效水深截断系泊系统的优化设计

深海平台设计通常需要混合模型试验,为了和全水深的系泊系统特性尽量保持一致,除了水深和跨距变小外,其他的特性采用改进了的自适应混沌粒子群算法(ACPSO)对截断后的系泊系统进行优化设计,使其特性尽量和全水深相似;以一FPSO,工作水深为914.4m为例,截断水深为214.4m,同时考虑总系泊系统水平和垂直两个方向以及具有代表性的单根系泊缆静力特性相似对等效水深截断系统进行了优化计算;数值试验结果表明,选取的数学模型、优化方法是快速有效的。     

单臂式空间机械臂捕捉空间目标问题研究

以空间机械臂系统的动量守恒关系式为基础,对空间机械臂抓取空间目标过程中的碰撞问题进行了分析,提出了“直臂抓取”与“广义直臂抓取”概念,详细推导了满足基座质心、系统质心及工作端点共线的机械臂构型,得到了碰撞力方向矢量与基座、系统质心重合的角度关系式．满足关系式的空间机械臂构型可有效的减少碰撞力对于系统角动量的影响,进而避免混合体控制问题的关节限制与力矩限制．通过仿真验证了方法的有效性．     

时滞柔性关节机械臂自适应位置/力控制

针对具有时滞的柔性关节机械臂自适应位置和力控制问题进行了研究.首先,通过坐标变换得出降维的位置/力控制模型.随后,将时间滞后近似表示成一阶滞后,进行时滞补偿.利用自适应算法修正机械臂系统参数,克服模型参数不确定性对系统的影响.同时,采用反步控制技术设计机械臂位置/力控制器,运用Lyapunov稳定性定理证明控制器能使机械臂位置和力跟踪误差收敛.最后的仿真研究验证了控制方案的有效性.     

基于全耦合时域运动模拟的FPSO艏摇失稳研究

本文建立系泊浮体全耦合非线性六自由度方程,研究了规则波中FPSO的艏摇失稳现象.将数值求解得到的平衡艏摇角与试验结果进行对比,验证了方程的准确性.分析了艏摇失稳对FPSO运动响应的影响,研究了初始艏摇角、波陡对FPSO艏摇失稳和运动响应的影响.结果表明：FPSO在特定波长船长比下会发生艏摇失稳现象,作用在船体上的波浪载荷增大,从而引起较大的横摇和垂荡响应;波陡不会影响最终平衡艏摇角,但会影响艏摇达到平衡所需的时间以及运动响应幅值;初始艏摇角会影响FPSO最终达到的平衡位置和运动响应.     

Thruster assisted position mooring based on structural reliability

This paper addresses dynamic positioning of surface vessels moored to the seabed via a spread mooring system, referred to as position mooring. In normal weather conditions, the mooring system constrains the vessel and the controller applies thruster force for motion damping and heading control, only. When environmental loads due to wind, waves, and current increase, thruster assistance is required also for positioning in order to avoid damage to the mooring lines. While traditional position mooring systems apply thruster force based on constraining the vessel to lie within a predefined geographical region, the controller designed in this paper instead employs structural reliability measures for the mooring lines to restrict movement. These structural reliability measures become an intrinsic part of the controller, enabling it to automatically adjust the admissible region for the vessel in the presence of changing winds, currents, and waves.     

浮筒转塔式系泊系统中的动态管缆数值分析

借助有限元法,结合非线性时域分析,对浮筒转塔式系泊(Buoyant Turret Mooring,BTM)系统与FPSO脱离前后分别采取不同的分析策略,解决其柔性立管、动态脐带缆和动态电缆(合称动态管缆)的设计分析工作量大以及所面临的高度非线性和强耦合等难题.以我国南海某BTM系统的动态管缆的分析为例,借助专业立管分析软件Orcaflex展示该类系统的数值建模和分析技术,并通过极值和疲劳的分析与评价阐述此类工程设计的技术特点.     

Robust Adaptive Dynamic Surface Control Based on Structural Reliability for a Turret-moored Floating Production Storage and Offloading Vessel

For floating production storage and offloading (FPSO) vessels, a dynamic positioning controller is necessary because using only a mooring system is not possible to keep the ship within a predefined region. Position control of the FPSO vessel is extremely challenging due to model uncertainties and unknown control coefficients. This paper develops a new robust adaptive positioning controller consisting of several components: adaptive law, dynamic surface control (DSC) technology, sigmoid tracking differentiator (STD), Nussbaum gain function, and structural reliability index. Model uncertainties can be estimated by the adaptive law derived from the Lyapunov theory. The DSC technology is used to eliminate repeated differentiation by introducing first-order filtering of the virtual control. The chattering-free STD with the characteristics of global fast convergence can estimate the derivatives of model uncertainties that are difficult to calculate directly. Therefore, the DSC and STD techniques make the proposed controller simpler to compute and easier to implement in engineering practice. Most of the traditional controllers require the information about the control coefficients to guarantee the stability of the closed-loop system while the Nussbaum gain function can remove the requirement for a priori knowledge of the sign of control coefficients. The capacity of the mooring system can be fully utilized to position the FPSO vessel by adjusting the structural reliability index on the premise of ensuring the safety of mooring lines, and hence less control effort is needed for the positioning controller. Simulations using two sets of system parameters demonstrate the proposed controller’s effectiveness. In addition, a qualitative comparison with the adaptive backstepping controller shows that our proposed controller is computationally more efficient and does not require a priori knowledge of the sign of control coefficients. A quantitative comparison with robust adaptive controller without the structural reliability shows that less control effort is needed using our proposed controller.     

新型缆风绳预紧及放松设备的控制系统介绍

在桅杆起重和各种高耸结构中,缆风绳是重要的稳定系统,起着稳定桅杆并承受桅杆起重吊装中部分载荷的作用。本文介绍了一种用于缆风绳预紧及放松设备的控制系统,包括控制系统的硬件结构、网络配置、软件结构等。     

单锚腿系泊系统参数化设计的研究

对单锚腿系泊系统的构成进行了分析,根据系统中零部件的结构尺寸作了 约束的定义,并据此对系统中零部件作了约束分析,简化了系统参数化设计的复杂性,使得 系统结构的约束分析条理清晰;在约束的定义和分析后,对系统的各零部件进行了关联分析, 确定了建模顺序,在SolidWorks 平台上开发出单锚腿系泊的参数化设计系统。     

Ensuring mooring line integrity by dynamic positioning: Controller design and experimental tests

This paper addresses the dynamic positioning of surface vessels moored to the seabed via a turret based spread mooring system, an operation referred to as the position mooring. While the mooring system keeps the surface vessel in place most of the time, thruster assistance is needed in severe weather conditions to avoid mooring line failure. Traditionally, this is done by keeping the vessel within a predefined geographical region. We present a conceptually new controller for position mooring operations. By using a structural reliability measure for the mooring lines, the new controller protects the mooring system whenever needed as a result of severe weather conditions and high environmental loads. This is done by maintaining the probability of mooring line failure below a preset value. In particular, the excessive use of thrusters caused by conservatively defined safety regions in conventional PM systems is avoided, giving a fuel optimal operation. The feasibility of our controller is successfully verified in laboratory experiments.     

Robust adaptive control of a thruster assisted position mooring system

In this paper, robust adaptive control is developed for a thruster assisted position mooring system in the transverse direction. To provide an accurate and concise representation for the dynamic behavior of the mooring system, the flexible mooring lines are modeled as a distributed parameter system of partial differential equations (PDEs). The proposed control is applied at the top boundary of the mooring lines for station keeping via Lyapunov’s direct method. Adaptive control is designed to handle the system parametric uncertainties. With the proposed robust adaptive control, uniform boundedness of the system under the ocean current disturbance is achieved. The proposed control is implementable with actual instrumentations since all the signals in the control can be measured by sensors or calculated by using a backward difference algorithm. The effectiveness of the proposed control is verified by numerical simulations.     

具有输入延时的锚泊自动定位系统保性能控制

从半潜式平台定位系统的经济性及安全性角度出发,提出基于锚链切换控制的自动锚泊定位系统新方案.针对方案中具有输入延时及不确定性的特点,设计了带有输入延时的保性能控制器,以产生抵抗环境扰动所需的控制输入.基于LMI方法给出控制器存在的充分条件,通过求解相应的线性矩阵不等式得到系统的保性能控制律.仿真结果表明,所设计的控制器能有效解决锚泊自动定位系统的参数不确定性及输入延时问题,从而提高系统的精度和性能.     

Post-adoption switching behavior for online service substitutes: A perspective of the push–pull–mooring framework

The post-adoption behaviors of online service users are critical performance factors for online service providers. To fill an academic gap that persists regarding bloggers’ switching behavior across online service substitutes, this empirical study investigates which factors affect bloggers who switch social network sites, in an attempt to understand specifically how push, pull, and mooring factors shape their switching intentions. The data to test the hypotheses come from an online survey of 319 bloggers, analyzed using partial least squares techniques. The results confirm positive influences of push and pull effects, a negative influence of mooring effects, and an interactive effect of push and mooring on switching intentions. The push–pull–mooring framework thus is a useful tool for comprehending the competing forces that influence the use of online service substitutes. In particular, perceptions of weak connections and writing anxiety push bloggers away, whereas relative enjoyment and usefulness pull bloggers to social network sites; switching cost and past experience also inhibit a change. These findings offer key insights and implications for the competitive strategy choices of online service providers.