【作者】 王龙金；

【导师】 金鸿章；

【作者基本信息】 哈尔滨工程大学 ， 控制理论与控制工程， 2009， 博士

【摘要】 船舶在海上行驶过程中由于受到海浪、海风和海流等各种海洋扰动的作用,不可避免的要产生六自由度运动,即横摇、纵摇、艏摇、横荡、垂荡和纵荡运动。在同种海洋干扰环境下,船舶的横摇运动较为剧烈,严重影响船载设备的正常运行、船舶乘员的舒适度和船载货物的安全性。传统减摇鳍是目前最常用且应用最成功的船舶主动式减横摇装置,减摇效果可达90%以上由工作原理所限,只有当船舶处于中高航速时,传统减摇鳍才可以有效地减摇,在低航速或零航速情况下,传统减摇鳍几乎不能进行减摇。现有的减摇设备中,只有减摇水舱的减摇效果不受航速影响,但是减摇水舱体积较大,而且只是在谐摇频率的附近才能取得较好的减摇效果,在某些情况下甚至会出现增摇的现象。为实现船舶在全航速下的有效减摇,有些船舶采用同时安装减摇鳍和减摇水舱两种减摇设备。采用两套减摇设备虽然能取得良好的减摇效果但经济效益欠佳。本文以设计一种具有零航速、低航速和中高航速种工作模式的全航速减摇鳍系统为前提,通过工作模式的转变实现在减摇鳍控制下船舶全航速航行状态下的有效减摇。中高航速减摇鳍系统已经相当成熟,本文将重点从零／低航速减摇鳍升力模型和系统控制策略两方面对零／低航速减摇鳍系统进行研究。本课题来源于国家自然科学基金项目“零速下船舶仿生减摇鳍升力机理的研究(50575048)”和“基于变形仿生减摇鳍的水面机器人的减摇机理研究(50879012)”。主要研究零／低航速下减摇鳍基本工作模式、基于此工作模式的零／低航速减摇鳍升力产生机理,以及零／低航速下减摇鳍系统控制策略。论文首先从零／低航速减摇鳍系统安装方式和工作原理的角度对零／低航速减摇鳍系统进行了系统的阐述。介绍了基于Weis-Fogh机构零航速减摇鳍系统、基于纵向拍动工作模式零航速减摇鳍系统、基于变形鳍技术零航速减摇鳍系统和基于纵向拍动工作模式低航速减摇鳍系统四种减摇鳍系统的安装方式和工作原理。分析并得到零/低航速下减摇鳍升力模型是零／低航速减摇鳍系统设计的关键,从系统实现和减摇效果的角度出发,本文将重点对基于纵向拍动工作模式零航速减摇鳍系统、基于变形鳍技术零航速减摇鳍系统和基于纵向拍动工作模式低航速减摇鳍系统进行研究。依据流体力学理论对基于纵向拍动工作模式的固定翼型零航速减摇鳍升力模型、基于变形鳍技术零航速减摇鳍和低航速减摇鳍升力模型进行分析。针对减摇鳍的实际工作环境,我们将减摇鳍在流体中转动时产生的升力分为理想流体环境和非理想流体环境两部分分别进行分析。在理想流体环境下我们通过一系列保角变换、运动变换求得鳍面在理想流体中转动时引起的流场复势,然后采用伯拉休斯定理,分析得到理想流体中鳍面转动时产生升力数学模型。在非理想流体环境下,由于流体存在粘性,因此鳍面在转动的过程中势必会在鳍面产生旋涡,旋涡会在鳍面两侧产生压力差,产生阻碍鳍面转动的阻力,从而影响鳍面转动时产生的升力。由于鳍面在转动时引起的旋涡变化复杂,从工程应用的角度出发,在对鳍面旋涡作用力进行分析时,我们忽略鳍面厚度,采用相对简化的旋涡模型分析得到鳍面在非理想流体中转动时产生的升力数学模型。由于船舶的航行情况及装载情况并非固定不变,这就使得船舶横摇运动模型存在一定的时变性。通过分析我们得到的零/低航速减摇鳍升力模型都存在一定的非线性特性,这就使得零/低航速减摇鳍系统具有一定的非线性和时变特性。由于支持向量机具有良好的小样本辨识能力,因此我们采用基于支持向量机在线辨识的前馈逆控制器设计方法来解决系统的非线性特性和时变特性。支持向量机辨识是一种无误差反馈辨识,因此支持向量机对系统的辨识有可能存在一定的不足,这将影响系统的稳定性和稳态性,同时当系统模型突然发生变化时支持向量机也需要一定的时间对系统进行辨识。为解决因支持向量机辨识不足和系统模型突变引起的系统控制不足的问题,我们引入了基于支持向量机和模糊控制相结合的复合控制策略,通过模糊控制器保证支持向量机辨识过程中系统的稳定性和稳态性。定义一个协调因子,根据系统运行效果调整两种控制策略所占的比重,根据协调因子的数值决定支持向量机是否需要重新对系统进行辨识和系统辨识是否充分。该控制结构既具有支持向量机逆控制设计简单、稳态精度高的优点,同时结合模糊控制响应快速,抗干扰能力强,鲁棒性好的优势,既保证了系统的稳定性又保证了系统的稳态性。采用本文分析得到的零/低航速减摇鳍升力模型搭建船舶零/低航速减摇鳍系统模型,依据本文提出的控制策略对系统进行控制器设计,并对系统进行仿真。仿真显示三种减摇鳍系统均取得了良好的减摇效果,证明了本文设计的零／低航速减摇鳍系统的有效性。由于零航速减摇鳍升力容量有限,随着海情的增加两种零航速减摇鳍系统减摇效果有所下降,与零航速减摇鳍相比低航速减摇鳍具有较大的升力容量,其减摇效果受海情影响不大。更多还原

【Abstract】 When the ship sails on the sea, it will move in six degree of freedom for the disturbance of ocean wave,sea breeze,ocean current. The rolling movement is the most serious under the same ocean disturbance. Rolling movement has a serious effect on working order of the equipment in the ship, the cosiness of passenger and the security of goods on the ship. Fin stabilizers are the most successful and most widely used active equipments for ship anti-roll.90 percent of roll motion can be eliminated by using fin stabilizers. As the work principle of fin stabilizer, it can effectively reduce the rolling movement when the ship sails at a high speed and it can not reduce the rolling movement when the ship sails at a low speed or zero speed. Among existing equipments, only the effectiveness of ship anti-roll tank is not affected by the speed of ship. But the volume of tank is usually too large. Ship anti-roll tank can work well when disturbance resonance frequency is close to that of ship. If the resonance frequency doesn’t match, the roll motion of ship might be strengthened. In order to reduce ship roll movement at all speed, some ships adopt ship anti-roll tank and fin stabilizer together. Though it can get good perfection, it is not a economical method. In this dissertation we dedicate to research a fin stabilizer system with three kinds of working method which are zero speed,low speed and high speed working method. Fin stabilizer system at high speed has been well developed. We will mainly research on zero and low speed fin stabilizer system.The dissertation is based on project supported by national science foundation of China:Research on lift theory of ship bionic roll stabilization at zero speed(50575048) and Research on antiroll of underwater vehicle near surface based on Transmutative Fin (50879012). It mainly researches on the working mode of zero and low speed fin stabilizer,the lift model of zero and low speed fin stabilizer and the control strategy of zero and low speed fin stabilizer system.The working mode and the fixing fashion of zero and low speed fin stabilizer are firstly expatiate. Then four kinds of zero and low speed fin stabilizer system which are zero speed fin stabilizer system with Weis-Fogh mechanism, zero speed fin stabilizer system with lengthways movement, zero speed fin Stabilizer system with transmutative fin and low speed fin Stabilizer system with lengthways movement.The key factor in designing of zero and low speed fin stabilizer system is to analyse and get the lift model of fin at zero and low speed. We will mainly research on zero speed fin stabilizer system with lengthways movement, zero speed fin Stabilizer system with transmutative fin and low speed fin stabilizer with lengthways movement for their predominance. We analyse the lift generated on the fin in ideal hydro environment and nonideal hydro environment. We get the lift model in ideal environment with conformal representation theory,movement transform theory and Blasius theorem. As glutinosity of the hydro in nonideal hydro environment, it will generate vortices on fins when fins move in nonideal hydro environment. The vortices will generate press distinction on two sides of the fin and it is one parts of lift generate on the fin. We ignore the thickness of fin for the complexity of vortices and adopt a applied method to analyse the lift generated by vortices.The model of ship rolling movement is variational for the change of sail and loading of the ship. All the three kinds of lift model are nonlinear. So the zero and low speed fin stabilizer system are a serious variational and nonlinear system. As SVM(support vector machine) has a good identification ability, we adopt a inverse control method based on SVM to solve the nonlinearity and time varying of zero and low speed fin stabilizer system. The identification of SVM is without feedback-error, So the identification of SVM to zero and low speed fin stabilizer system maybe has some insufficient and it will affect the stability and the stationarity of the system. SVM also need some time to identify the system when the system has a sudden change. We adopt a compound control strategy based on SVM and GAFC(fuzzy controller based on genetic algorithm) for the under-control of the system that is induced by the sudden change of the system and under-identification of SVM. The fuzzy controller will make the system has a good stability and the stationarity when SVM is identifying zero and low speed fin stabilizer system. Define a coordination factor, To adjust the proportion of the two kinds of control strategies and to determine whether to identify the system once again or the identification is sufficient based on the coordination factor. This control structure can make the system has a good stability characteristic and static accuracy.To construct zero and low speed fin stabilizer system with the lift model that we get and design controller with complex control strategy that we introduce. Simulation results show that all the fin stabilizer system get a good reduction of ship rolling angle and it prove the efficiency of zero and low speed fin stabilizer system. As zero fin stabilizer’s lift capacity is not very large,the anti-roll effect will decrease when the oceanic condition become more serious.As low speed fin stabilizer has a large lift capacity,the anti-roll effect of low speed fin stabilizer system is not severely affected by the oceanic condition.更多还原