全航速升力反馈减摇鳍控制策略研究

提出全航速减摇鳍控制策略,对低航速和中航速切换策略进行研究．采用升力反馈封装鳍角到升力的不确定性,避免在零航速和低航速下复杂的控制规律;同时,基于T-S模型将横摇非线性不确定系统转化为线性时变系统,并将控制中的约束非线性优化问题转化为二次规划问题,避免了预测控制中的非线性优化在线求解．以某船为例,给出了低中航速的切换控制策略,仿真结果表明了该方法可以使减摇鳍满足全航速减摇要求．     

船舶海浪中非线性随机运动的可视化技术

研究船舶海浪中运动的可视化技术.通过采用船舶在海浪中运动的可视化技术,可以使船舶设计人员能够更直观地了解船舶的运动性能.采用具有平台独立性的OpenGL图形库对船舶在波浪中运动的可视化进行描述,讨论了建立船舶模型的可行方法和如何建立三维波浪的数学模型.考虑随机波浪及船舶的非线性阻尼、非线性恢复力矩,建立船舶横摇运动的非线性微分方程.采用Runge-Kutta方法求解非线性微分方程,根据数值模拟结果,应用OpenGL中的函数来生成船舶在海浪中运动的动画.所开发的程序模拟的船舶和波浪是三维的,可以对不同有义波高的波浪和不同船舶的运动进行模拟.     

船舶零航速减摇鳍控制系统研究

船舶零航速减摇鳍是指在来流速度为0的流场中依靠鳍的主动摆动产生升力,以对抗海浪的作用力,从而减小系泊状态下船舶摇摆的减摇。设计了伺服控制系统,增加了升力限位环节。通过对有义波高分别为1,2m,浪向角均为90°海况下的仿真研究,减摇效果分别达到了78．30％和56．92％,优于减摇水仓减摇效果,证明所设计系统能够满足船舶零航速减摇的要求。     

船舶减摇非线性系统神经网络控制研究

本文针对船舶横摇运动的非线性模型，基于BP神经网络设计了一种船舶横摇减摇 自适应PID控制器．该控制结构由两个BP神经网络组成,实现了对被控对象输出的预测及PID控制器参数的自整定．仿真表明该控制器对减摇系统的非线性模型有很好的减摇效果．     

Determination of the dynamic angle of the bearing's rolling element location and of its influence on the loads and rolling friction

A model for determination and analysis of bearing external radial and axial load distributions per individual rolling elements and a model for determination of the resistance to motion of rolling friction, accounting for rolling element locations during the bearing track motion with respect to the direction the bearing radial load resultant vector acts, are presented. A dynamic angle of the rolling element location has been defined as well. The models have been developed to determine values of bearing load distribution parameters, individual rolling element loads, and resistances to rolling motion of bearings and rolling bearing systems, as well as to analyze distributions and values of the radial and axial stiffness of rolling elements, bearings, and kinematic pairs as a function of the bearing rolling element distribution and the direction along which the bearing radial load resultant vector acts. The proposed models have been built to carry out analysis of the resistance to motion of rolling kinematic pairs of industrial robot manipulators. Slow‐speed and short‐period motions of rolling bearings have been assumed as a characteristic type of motion of rolling kinematic pairs in manipulators. © 2000 John Wiley & Sons, Inc.     

动力定位船舶纵向运动的反步法控制器设计

本文研究了动力定位系统的控制策略,针对船舶动力定位系统模型的非线性特性,考虑到风浪流等外部环境扰动对船舶引起的恒值干扰及其不确定性,基于带有未知定常扰动的三自由度非线性船舶水面运动数学模型,应用自适应反步法设计船舶动力定位控制律,将Lyapunov函数选取和控制器设计相结合的回归设计方法,并在MATLAB软件环境下通过仿真研究验证模型和控制策略的有效性。在计算机仿真研究中,以26:1比例建造的2800mm×762mm×498mm船模为设计实例。     

一类非线性船舶在随机波上的倾覆概率仿真

研究一类非线性船舶在随机波上的倾覆概率仿真。船舶在给定随机波上的、直到颠覆的大幅度横摇可用一个四元非线性方程表示;假定噪声为白噪声的情况下,该方程通过转化可被改写成对应的二阶随机微分方程;基于半离散数值解法,设计了一类非线性船舶在随机波上的倾覆概率仿真算法,该方法简单,易于工程应用;给出实例演示了方法的应用,验证了算法的有效性。     

转子-轴承系统中滚动球轴承的非线性动力学相似特性研究

针对转子—轴承系统中滚动球轴承的动力学相似问题,提出一种考虑非线性振动特性的轴承系统相似模型建立方法.首先,建立滚动球轴承整体的非线性振动微分方程,运用积分模拟法推导了轴承整体的非线性振动特性相似关系,并结合滚动球轴承的动力学相似关系得到滚动球轴承系统的相似设计准则;其次,应用所得的相似准则,以深沟球轴承C204JUT为原型、6208为模型进行数值仿真实例计算,通过采用Newmark-β算法计算得到的分叉图分析了转速ω、径向载荷F_r、阻尼C及径向游隙γ大小对原型和模型轴承系统振动位移或速度响应的影响;最后,通过对比原型和模型的各参数(ω、F_r、C、γ)分叉图中分叉区间、趋于稳定运动参数值大小以及进入稳定周期运动时的稳态响应值大小验证相似准则的准确性和有效性.通过分析得到以下结论:1滚动球轴承非线性振动特性参数(如振动响应、结构阻尼等)相似关系可由轴承结构参数相似关系确定;2原型与模型非线性运动的分叉图形状一致,且模型能够很好的预测原型稳态振动响应,因此可将模型轴承用来预测原型轴承的非线性振动行为.     

零航速减摇鳍自适应主从控制器设计

零航速下鳍上的水动力与鳍角,角速度和角加速度存在记忆非线性关系,同时船舶横摇模型本身亦具有非线性和不确定性.导致常规控制方式无法直接求取控制量,且不能适应变化的模型和海况.本文通过主从控制器来分离减摇鳍系统的输出和输入非线性,对分离后的系统,采用基于径向基网络的逆控制构成主控制器来求取中间控制量,并自适应横摇模型和海况的变化.采用广义回归神经网络来逼近中间控制量到鳍角的映射作为从控制器.仿真结果表明该方法对横摇模型的不确定性具有自适应性,并可提高在变海况和高海况下的减摇效果.     

利用SESAM软件对驳船进行水动力性能分析研究

驳船是一种常用的工程辅助船,其水动力性能对作业安全有很大的影响。采用DNV船级社的SESAM软件系统,以某驳船为例,通过建立全船的有限元结构模型,对全船进行水动力特征分析与波浪载荷响应计算。计算表明：SESAM软件能够较准确地预报驳船的运动响应与计算波浪作用于船体的载荷。     

Finite element procedures for nonlinear structures in moving coordinates. Part 1: Infinite bar under moving axial loads

This paper deals with analyzing nonlinear structures under high-speed moving loads by use of the finite element method. The stationary response of an infinite bar posed on a Winkler foundation under constant moving loads is investigated. Instead of the transient analysis, the stationary solution of this problem is obtained by solving a static system in a reference frame which moves with the load for reducing the computation cost. To overcome the difficulty due to numerical instabilities when considering very fast loads (supersonic loads), a new procedure to govern the finite element formulation in moving coordinates is proposed. Comparing numerical solutions with analytical ones shows that the proposed method is valid for all values of load speed. Last, an example of nonlinear elastic foundation is considered to outline the nonlinear effects.     

轴承预紧力对转子系统静动态特性的影响

轴承预紧力的大小直接影响到滚动轴承-转子系统的静动态特性. 综合考虑离心力和陀螺力矩效应,在Romax软件中建立了5自由度轴承-转子系统动力学模型,分析了预紧力对轴承刚度、工作接触角以及工作寿命的影响,并搭建了轴承 转子系统试验台做验证试验. 在不同轴承预紧力下,分别研究了轴承刚度、工作接触角、工作寿命、静载荷作用下轴承 转子系统的静变形以及动不平衡载荷作用下主轴系统的振动响应等,并在轴承-转子试验台上进行试验验证,得到了轴承预紧力与这些因素的关系曲线. 在此基础上,研究了预紧力对转子系统固有频率的影响,结果表明加大预紧力有助于提高系统的固有频率. 研究结果可为轴承-转子系统的设计与分析提供理论参考.     

Fuzzy Control for Equilibrium and Roll-Angle Tracking of an Unmanned Bicycle

This study presents steady turning motion and roll-angle tracking controls for an unmanned bicycle. The equations of motion describing the dynamics of a bicycle are developed using Lagrange's equations for quasi-coordinates. Pure rolling without slipping constraints between the ground and two wheels are also considered in this model. These constraints introduce four holonomic and four non-holonomic constraint equations to the model. For the developed bicycle dynamics, one PID and one fuzzy controller that create steering torque are derived to recover the balance of the bicycle from a near-fall state. Furthermore, another fuzzy controller is added for controlling the bicycle to a desired roll angle which leads to its steady circular motion. The bicycle can track a given roll angle while maintaining its balance. The effectiveness of the control schemes is proved by simulation results.     

船舶零航速减摇鳍升力测量研究

船舶零航速减摇鳍是指在来流速度为零的流场中依靠鳍的主动摆动产生升力,以对抗海浪的作用力,从而减小船舶摇摆的减摇技术。在升力测量中,将升力控制引入零航速减摇技术中,根据实船安装环境几个耦合因素的影响,针对零航速减摇鳍,设计了零航速减摇鳍升力传感器;通过反馈信号合成算法,合成的升力信号有足够的精度,证明所设计系统能够满足船舶零航速减摇的要求。     

船舶在波浪中运动的计算机仿真

该文叙述了将虚拟现实技术运用到船舶运动中的可行性和方法，介绍了在虚拟现实环境中整个船体的建模方法与步骤。然后根据船舶在规则波中的频域六自由度运动方程，理论计算船舶在规则波中的六自由度运动响应。在数值模拟的计算机编程中，使用了Visual C 编程语言并结合Ooen GL(Open Graphics Library)图形接口技术，开发了一套船舶运动仿真的软件系统。     

On the Modeling of Friction and Rolling in Flexible Multi-Body Systems

This paper is concerned with the dynamic analysis of flexible, nonlinear multi-body systems undergoing contact involving friction and rolling. A continuous friction law is used to model the friction forces between contacting bodies. This avoids the numerical problems associated with the discontinuity inherent to Coulomb's friction law and eliminates the need for different sets of equations modeling sliding and rolling as distinct phenomena. On the other hand, continuous friction laws eliminate specific physical phenomena implied by Coulomb's friction law. The condition of vanishing relative velocity between two contacting bodies is not possible: sticking or rolling are replaced by creeping with a small relative velocity. Discrete events such as transition from slipping to rolling or rolling to slipping are eliminated, together with the high frequency phenomena they are likely to cause. The computational issues associated with the continuous friction law and with the enforcement of the non-holonomic rolling constraint are addressed in this paper. This work is developed within the framework of energy preserving and decaying time integration schemes that provide unconditional stability for nonlinear, flexible multi-body systems undergoing contact involving friction and rolling.     

Electrohydraulic force control design of a hardware-in-the-loop load emulator using a nonlinear QFT technique

This paper presents the design of a robust force control system for an electrohydraulic load emulator utilized as part of a hardware-in-the-loop flight simulation experiment. In this application, the force controlled hydraulic actuator is used to artificially recreate in-service loads upon a second hydraulic flight actuator operated in closed-loop position control. Electrohydraulic force control is more difficult than electrohydraulic position tracking because the load dynamics influence the force transfer function in a way that makes it challenging to develop an accurate force tracking system using simple feedback control. Nonlinear quantitative feedback theory (QFT) is applied in this paper to address this issue. First, an effective and robust feedback controller is designed by nonlinear QFT to desensitize the force control loop to nonlinear servovalve flow/pressure effects and typical system uncertainties. A secondary compensator is also designed within the QFT framework to extend the force tracking bandwidth with respect to the load motion. Experiments demonstrate acceptable force tracking performance within the scope of a representative flight-simulation experiment.     

计及螺旋桨负载的船舶电力系统协调控制设计

推进负载对船舶电网的暂态稳定性影响是船电系统的主要特征之一.本文基于非线性鲁棒L2干扰抑制控制方法,研究了具有螺旋桨负荷的船舶电力系统中的励磁与调速的协调控制问题,在充分分析了柴油发电机组的非线性数学模型及其螺旋桨负载的相互耦合的非线性动态结构特性的基础上,提出backstepping控制技术与L2干扰抑制相结合的综合协调控制策略来设计控制器.该控制器在保证系统稳定的条件下,有效地抑制干扰对发电机系统电压和频率的影响.仿真表明,在给系统突加螺旋桨负载的情况下,该控制器能有效地抑制负载对系统性能的影响,验证了控制器的有效性.     

A practical fuzzy controllers scheme of overhead crane

This paper presents fuzzy-based design for the control of overhead crane.Instead of analyzing the complex nonlinear crane system,the proposed approach uses simple but effective way to control the crane.There are twin fuzzy controllers which deal with the feedback information,the position of trolley crane and the swing angle of load,to suppress the sway and accelerate the speed when the crane transports the heavy load.This approach simplifies the designing procedure of crane controller;besides,the twin controller method reduces the rule number when fulfilling the fuzzy system.Finally,experimental results through the crane model demonstrate the effectiveness of the scheme.     

A practical fuzzy controllers scheme of overhead crane

1IntroductionThe overhead crane systemis widely usedinindustryformoving heavy cargos .Thus anti_sway and position controlhave become the requirements as a core technology forautomated crane systemthat are capable of flexible spatialautomatic conveyance .The purpose of crane control is to reduce the swing ofthe load while movingthe trolleyto the desired position asfast as possible .However ,the overhead crane has seriousproblems :the crane acceleration,required for motion,always induces undesir…