通过键合图对剪刀举升原理做动态分析课程毕业设计外文文献翻译@中英文翻译@外文文翻译

中国地质大学长城学院 本科毕业设计外文资料翻译 系 别： 工程技术系 专 业： 机械设计制造及其自动化 姓 名： 殷玉磊 学 号： 05211521 2015年 4 月 1 日 外文资料翻译译文 通过键合图对剪刀举升原理做动态分析 Md Toufiqul Islam, Cheng Yin, Shengqi Jian, and Luc Rolland 摘要 本文描绘了基于键合图建模框架 的剪刀举升机理（即四杆并联机构）下普通多体系统动力的实现。剪刀举升机理是高低汽车工业的首选，系统有一个自由度，有一些源于经典力学刚体动力学方程的程序 (例如 Classic Newton-DAlembert, Newton-Euler, Lagrange, Hamilton, kanes to name a few)，但是这些对于大型复杂系统计算量特别大，从而容易出错，这里我们将生成机理的多体动力学模型键合图，因为它为不包含任何因果关系冲突和控制工程的闭环运动模型提供了灵活性。本文中的机理是建模和模拟，以便评估一些特定应用需求，如动态和位置精度。提出的机理的多体动力模型提供一个准确快捷的方法来交接分析动态机理，这里没有采用剪刀举升机构。仿真给了一个关于处于线性位移机理的不同链接长度的电动机转矩大小的清晰想法。 1、 介绍 剪刀举升类型升降平台的主要用途是有无人工的负载垂直运动，它们被广泛用于组装工作 (如飞机零部件装配 ,发动机部件组装 )，维护结构也可用于内部材料运输系统。如果正确安装在汽车或卡车，即适应不同的用途，剪刀举升机构可以移动 1。大型复杂的机械系统越来越重要，为了剪刀举升机理的特有性和功能性，动态仿真系统 非常重要，因为他们的主要功能是提高劳动者的工具和负载所需的高度 ,同时允许操作员控制电梯的运动和位置。因此剪刀举升机理的适当设计、制造和维护，提高了劳动者的工作效率和安全系数 2。不幸的是，剪刀举升操作中也会发生致命和非致命事故事故 3,4。因此对于调查系统的动态行为，适当的动态模型是很有必要的。这种机理有四杆机构和曲柄滑块机构组成，图 1显示了这两种机构，图 2显示了完整的剪刀举升机理。这些链接形成了一个平行运动机理并有转动关节链接。每个四个链接形成一个所有链接长度一样的菱形结构，驱动机构与位于地面移动平台 的底部连接，基于设计准则，驱动机构可以是电动、液压、气动，系统可以以不同的方式连接它们，连接它们的一些受欢迎方法用来连接弯管接头的中心，或者作为曲柄滑块固定在底座上，或者连接到执行机构（如液压、气动）。这里我们把直流电机作为驱动机构，它位于底部与曲柄滑块连接，第二节中介绍关于多体动力学的问题，第三节分析机构运动，第四节介绍系统动态模型的开发过程，第五节提出了仿真结果，第六节进行模型验证，第七节讨论模型，最后，第八节得出结论。 图 1.四杆机构和曲柄滑块机构 图 2.2个剪刀举升机构的基本框架 2、 背景研究 1603年，缩放仪由 Christopher Scheiner发明，被视为四杆机构的第一个例子 5，后来， James Watt提出四杆机械装置，可以做近似直线运动 6。一些机构用来产生直线输出运动，其输入元素在一天旋转、震荡、移动的直线上。由四连杆机构组成的剪刀举升装置是 Larson等人于 1966年创建的 7，这种机械装置与可扩展的负载升降机构相关，更特别的是，这涉及到包括相对立的剪刀机构，每一个剪刀机构包含一对完全连接的剪刀手臂，伴随着升降相对关键的运动。与当代设计相比，可以提供相对大量链接长度相对较 短向上扩展，由于是并行装置，重量非常小刚性更好。这种机制的另一个优点是 ,它是相对自由的复杂的连锁系统 ,但仍有高能力的扩展与短臂。 A 多体动力学 在 6中讨论奇点配置和菱形的运动机构，在 8中探讨了基于 Matlab仿真描绘系统运动分析的另一种方法。尽管有两篇文献提到了动态剪刀举升机构的处理，文献数量有限，但是已经详尽研究了多体动力学建模与仿真的一般问题。尤其是多体动力分析由于像 Newton, DAlembert, Euler and Lagrange这样的先驱有了丰富的历史的发展。在 910中可以发 现关于多体动力学的文学综述。首先，基于牛顿力学研究多体动力学系统，欧拉后来用框架来研究刚体运动，他还利用 freebody原理建模约束和关节，到目前为止牛顿欧拉方程适用于多体动力学的研究。与欧拉同时代的拉格朗日还建立了约束力学系统的系统分析，变分原理应用于系统的总动能和势能考虑其运动学约束和相应的广义坐标的拉格朗日方程结果的动态分析是非常有用的多体系统，进化的多体系统动力学理论和经典力学和刚体系统的应用可以归因于有效的数值方法的发展解决高度非线性方程组产生的动态系统 9。在这种演变过程中，研究人员对建模形式 做出了贡献，根据 9，这些形式可分为两类 ,即数字和符号。在 10中 Sinha等人把建模的方法分为两组，第一组与由基于图论的系统建模生成的组件相关，线性图理论用于分析多体动力学，例子包括 1112。除了线性图，结合图也被用于多体动力学模型，如 131415。在 16中，Diaz等人描述了 3D立体建模的线性图表方法，他们还直接推论线性图表反映了系统的拓扑结构；因此，它更容易让非专业人士创建系统描述。第二组是基于模块化、面向对象的模型 ,可以分层次组合成完整的系统，例如 1718。在 19中 Antic等人描绘了结合图的优点，他们提到理论上它可以描绘子系统和形式主义之间的层次结构和联系。这提供了计算机建模和仿真的支持。 B 计算多体动力学 对于建模机理，多体系统社区开发了许多软件工具；然而，它们在模型描述、力学基本原理的选择和拓扑结构上广泛不同，以至于不存在统一的描述模型 9。在20Gillespie等人提出了一种计算多体动力学的全面审查。一些商业软件包可用于数值解决多体动力学问题，其中一些基于计算机辅助工程 (CAE)；例如包括 ADAMS21 DADS 22 和 MESA VERDE 23。 Dymola和 Modelica是两个大型系统建模的面向对象的建模语言 16。 20-Sim软件是一个键合图模型多体动力学系统非常有效的和高效的工具 24。它提供了允许创建模型快速和直观的工具，模型可以通过使用方程 ,建立块图、物理组件和结合图来建立，它提供了各种建立不同模型的工具箱，模拟和分析他们的性能。该软件还包含 3 d机械工具箱为多体建模提供灵活性。 图 3.动力学分析 3、 机理的运动分析 在 7中描述了基于剪刀举升机理的短暂的液压执行机构的运动分析。在多阶段剪刀举升机理中动链接形成一个 菱形的配置， Dr. Rolland做了菱形结构配置和重复菱形结构的详细运动学分析 5。剪刀举升的运动分析可以通过观察图 3 的循环。从图 3 中 错误 !未找到引用源。 102 循环形成一个等腰三角形，所以 错误 !未找到引用源。 。输入为 s 输出为 h。应用勾股定理： 把（ 4）对时间求导得到速度。 由 (1)我们可以得到反向关系： 把（ 6）对时间求导得到： 把 h对 求导得： 图 3中 H=2h，图 2中总高度是 4h，把（ 5）和 (7)对时间求导得到加速度。 4、 动力学机理 Dong等人调查剪刀的动态稳定性提升 机制，并基于动态特性的仿真研发了集总参数模型 2。这是一个基于实际工作的方法而且在整个系统上没有提出动态模型，因此本文提出一种动态模型的完整系统，有吸引力的和快速的所需的时间和精力相比 ,经典的动力学建模方法。 图 4.链接示意图 A、 每个链接的键合图模型 对于一个单波束的键合图模型身体被认为是质量和转动惯量，外部力量应用于 A、B端口，当多体系统中的所有身体包含三个惯性坐标 (x,y,)，制定会变得更容易， B点速度相对 G点的速度关系为： G点是链接的重力中心，设 G点到 B点的距离为 r，则方程将是： 根据 以上方程， B点的 x、 y轴的分量为： （ 14） G点相对 A点的速度为： A点在 x、 y轴的速度矢量和表示为： 为使 A、 B固定，我们只需在附加力的键合图上应用零流源或近零， MTF用于键合图的速度限制。图 4显示了梁的键合图，其中长度、质量和惯性参数被视为总体参数。 图 5.链接键合图 B、 寄生刚度和阻尼 为了建模每个机械联合，要考虑寄生刚度和阻尼。刚度和阻尼是许多机械系统设计的重要标准。刚性联轴器弹簧用于使用机械连接来消除系统的微分因果关系。我们可以用寄生刚度和 /或电阻元素 移除能量储存元素之间的依赖关系 25，图 6. 显示了寄生刚度和阻尼结构应用于键合图的设计。 C、 电机建模 在提供的直流电机中，电压通过串行连接的电感和电阻去向电枢，然后电枢提供电动势作为机械输出。为了在键合图中建模直流电机，阻力和回转器元素用于表示上述标准。电机轴是通过电感和电阻元件建模，图 7显示了直流电机的键合图模型。 D、 控制机制 作为单自由度系统， PID控制器已被选中， PID将在当前平台位置和期望平台位置相比较，基于两个高度之间的差异控制电动机的输出，图 8显示控制机制的示意图。 图 6. 寄生刚度和阻尼 图 7. 直流电机键合图 PID 分别代表比例、积分和导数， PID 参数调优实现了反复试验优化方法，这主要基于猜测和检测。在这种方法中，主要贡献是比例作用 ,它可以通过积分和微分作用。控制机制是有限制的，它将把输出限制在制定范围内，以便不切实际的的值驱动电机，限制块后面是一个调制源。有两种可用的键合图工作源，一个是固定的 ,另一个是可变的，对于 PID控制器提供的电机不同输入，这里我们使用不同的变量工作源。电机之后的变压器把旋转运动变为直线运动。 图 8.控制机制 5、 仿真 表 1.仿真结果 图 9.菱形阶梯剪刀 举升平台的键合图 A、 向上运动的仿真（期望高度为 6m，初始高度为 5m） 图 10.平台从初始高度到期望高度 图 11.原动件初始运动需求 图 12.原动件速率 图 13.加速效应 B、 向下运动仿真（期望高度为 4m，初始高度为 5m） 图 14. 平台从初始高度到期望高度 图 15. 原动件初始运动需求 图 16. 原动件速率 图 17.加速效应 6、 仿真结果 对于第一次仿真平台从初始高度 5m移动到 6m（图 10），根据图 2的剪刀升升机制基础上的驱动链接应该从其原始位置向后的方向在 D增加平台的高度从 5米到 6米 (图11)。图 12显示了驱动链的速率。衍生物的速度在图 13中给出了加速度。对于第二次仿真平台所需高度被设定为 4m，比初始高度 5m低（图 14）。根据机制基础上的驱动链接应该前进的方向在点 D降低平台的高度和平台高度应该从 5米减少到 4米 (图 15)。图16显示了驱动链的速率。图 17显示了所需的向下运动最终效应加速度。现在我们可以说从模拟结果曲线清晰地描述该模型的功能。 7、 讨论 本文提出一种充分剪刀举升控制机制模型，对比结果不幸的是没有得出剪刀举升机制的产物。该模型可以描述整个动力学 (位移、速度、加速度等 ),系统的输入 是电动机转矩，模型的另一个重要方面是包含控制器的机制，对于动态系统最传统的方法可以不包括控制，但键合图提供了包括电机动力学和控制重要的优势，这实际上是允许完整的自动动态系统仿真，键合图建模框架的另一个关键优势是快速的分析机制，剪刀举升机制在速度和加速度上响应不快，但是我建议在产业中进行快速直线运动。在产业里机制可用于构建高性能线性致动器，这里键合图建模比方程建模更具优势，因为它使用了图形的方法，并能快速简易实现，键合图利用二维图纸的关系可表达方程编程相比之下更自然 26。在模拟中不同参数组合可以用来模拟观 察反应，从仿真输出来看，可以出发一些优化一些想法，如仿真可用于电动机转矩的优化剪刀提升机制 ,由于键合图仿真非常迅速，几个参数组合可以在很短的时间内模拟，该模型的缺点之一是软件不可用。为优化PID控制器在这里我们使用了猜测和检查方法，但我们可以实现任何其他 PID调优技术，在 20-sim PID块包含温顺常数，它影响差异化的行为，理解一个 PID回路是基于线性控制 , 它可能不会给剪刀举升平台上由非线性方程管理的最好结果。 8、 结论 在这项研究中剪刀举升机制的动态行为建模和模拟使用商业软件包（ 20sim），模型的函数性 由所需输出条件的应用程序来证明。使用控制机制的一个合适的控制器 (PID控制器 )，仿真结果表明 ,该设计几乎可以模拟一个实时应用程序和仿真数据可以有效地用于优化设计，工业优化专业软件 (例如设计专家 ,一款统计软件等 )都可以使用。 20 sim软件包键合图建模和解决提供了良好的灵活性。尽管程序需要一些时间学习适度陡峭的学习曲线，自动化的模型生成功能可以在开发阶段的多体系统提供很大的帮助。 外文原文 题目： Dynamic Analysis of Scissor Lift Mechanism through Bond Graph Modeling Md Toufiqul Islam, Cheng Yin, Shengqi Jian, and Luc Rolland AbstractThis paper describes the implementation of general multibody system dynamics on Scissor lift Mechanism (i.e. four bar parallel mechanism) within a bond graph modeling framework. Scissor lifting mechanism is the first choice for automobiles and industries for elevation work. The system has a one degree of freedom. There are several procedures for deriving dynamic equations of rigid bodies in classical mechanics (i.e. Classic Newton-DAlembert, Newton- Euler, Lagrange, Hamilton, kanes to name a few). But these are labor-intensive for large and complicated systems thereby error prone. Here the multibody dynamics model of the mechanism is developed in bond graph formalism because it offers flexibility for modeling of closed loop kinematic systems without any causal conflicts and control laws can be included. In this work, the mechanism is modeled and simulated in order to evaluate several application-specific requirements such as dynamics, position accuracy etc. The proposed multibody dynamics model of the mechanism offers an accurate and fast method to analyze the dynamics of the mechanism knowing that there is no such work available for scissor lifts. The simulation gives a clear idea about motor torque sizing for different link lengths of the mechanism over a linear displacement. I. INTRODUCTION The main use of scissor lift type elevating platforms is vertical transportation of load with or without human. They are widely used for the assembly works (e.g. aircraft parts assembly, motor parts assembly), the maintenance of constructions or they can be used in the inner material transportation system. The scissor lift structure can be mobile if it is mounted on the vehicle or the right truck, i.e. adaptable to different purposes 1. There is an increasing importance of modeling and simulation of complex and large mechanical systems. For scissor lifting mechanism proper and functional dynamic simulation of the system has a great importance as their primary function is to elevate worker tools and load to a desired height while allowing the operator to control the movement and position of the lift. Therefore proper designing, manufacturing and maintenance of scissor lifting mechanism not only increase productivity but also workers safety 2. Unfortunately, fatal accidents and non-fatal incidents have also happened during scissor lift operations 3,4.Therefore a proper dynamic model is very necessary to investigate the dynamic behavior of the system. This mechanism is comprised of two very well-known mechanisms which are four bar mechanism and slider crank mechanism. Fig.1 shows the mentioned two mechanisms and Fig.2 shows the complete system model of the scissor lift mechanism. The links form a parallel kinematic mechanism and they are connected by revolute joints. Each four link form a rhombus like structure and where length of each link is same. There is a driving mechanism connected with the lower end of the moving link which is located at the ground platform. The driving mechanism can be electric, hydraulic or pneumatic based on design criteria. They can be connected to the systems in different ways. Some very popular ways of connecting them are to connect at the center of corner joint or connect it on the base as slider crank or connected to any actuator link (e.g. hydraulic, pneumatic etc.). But here we considered one DC motor as the driving mechanism. It is located at the base and connected with the slider crank. A brief literature review relating to this multibody dynamics problem is presented in Section II. The kinematics of the mechanism is analyzed in Section III. The development process of the dynamic model of the system is offered in Section IV. The result from the simulation is presented in Section V. The model was verified in Section VI. Discussion about the model is presented in the Section VII. Finally, Section VIII offers the concluding remarks. Fig. 1. Four bar and Slider crank mechanism Fig. 2. Basic Construction of 2 stage Scissor Lift Mechanism II. BACKGROUND STUDY In 1603, the Pantograph was invented by Christopher Scheiner, which may be regarded as the first example of the four-bar linkage 5. Later James Watt proposed a four-bar mechanism which can generate roughly a straight line motion 6. Some mechanisms are designed to produce straight-line output motion from an input element which rotates, oscillates or moves also in a straight line. However, the scissor lifting mechanism an extrapolation from the four bar linkage was patented by Larson et al. in 1966 7. This mechanism relates to extensible lift mechanism for elevating a load. More particularly, this relates to such mechanism including an opposed pair of scissor mechanisms, each of which includes a pair of scissor arms pivotally connected together, where relative pivotal movement of the arms accompanies extension of the lift mechanism. In comparison to the contemporary designs, this mechanism can provide relatively large amount of upward extension with a relatively short link length. Weight is very small and rigidity is better due to parallel mechanism. Another big advantage of this mechanism is that it is relatively free of complicated linkage systems, but still capable of high extension with a short arm. A. Multibody Dynamics The singularity configurations and the kinematics of the rhombus part of the mechanism is discussed in 6. Another approach to describe the kinematic analysis of the system based on MATLAB simulation is discussed in 8. Though the mentioned two literatures dealing with the dynamics of the scissor lift mechanism are very limited, the general problem of modeling and simulation of multibody dynamics has been exhaustively studied. Especially analytic multibody dynamics has a rich history of development owing to pioneers like Newton, DAlembert, Euler and Lagrange. Detailed literature reviews on multibody dynamics can be found in 9, 10. Primarily, the study on the dynamics of multibody systems is based on Newtonian mechanics. Euler later contributed the framework to study the motion of rigid bodies. He also used the freebody principle to model constraints and joints. To date the Newton-Euler equations facilitates the study of multibody Dynamics. Eulers coetaneous Lagrange also established a systematic analysis of constrained mechanical systems. The variational principle applied to the total kinetic and potential energy of the system considering its kinematic constrains and the corresponding generalized coordinates result in the Lagrangian equations that are very useful to the dynamic analysis of multibody systems. Evolution of multibody system dynamics from the theory and applications of classical mechanics and rigid body systems can be attributed to the development of efficient numerical means to solve the highly nonlinear equations resulting from the dynamics of the system 9. In this evolution process, several modeling formalisms have been contributed by the researchers. According to 9, these formalisms can be categorized into two classes; namely, numeric and symbolic. Sinha et al. in 10 classified the modeling approaches into two groups. The first group is relevant to component based systems modeling that is based on graph theory. Linear graph theory has been used in the analysis of multibody dynamics; examples include 11, 12. Besides linear graphs, bond graphs have also been used to model multibody dynamics; e.g. 13, 14, 15. Diaz et al. in 16 describes linear graphs method to model 3D body mechanics. They also comment that linear graphs reflect the topology of the system directly; hence, it is easier for nonspecialists to create system descriptions. The second group is based on modular, object oriented models that can be hierarchically combined into complete systems; e.g., 17,18. Antic et al. in 19 describes the advantages of bond graph. They mentioned it can describe hierarchical structure and connections between subsystems of a system and formalism introduced in the theory. This offers computer support for modeling and simulation. B. Computational Multibody Dynamics For modeling of mechanisms the multibody systems community developed many software tools; however, they differ widely in terms of model description, choice of basic principles of mechanics and topological structure so that a uniform description of models does not exist 9. Gillespie et al. presented a comprehensive review on computational multibody dynamics in 20. Several commercial software packages are available to numerically solve the multibody dynamics problem. Some of these are based on Computer Aided Engineering (CAE); examples include ADAMS 21, DADS 22 and MESA VERDE 23. Dymola and Modelica are two object oriented modeling languages for large system modeling 16. 20-Sim software is a very effective and efficient tool to model multibody dynamic systems for bond graph 24. It provides tools that allow creating models very quickly and intuitively. Models can be created by using equations, block diagrams, physical components and bond graphs. It provides various tool boxes to build different models, to simulate them and analyze their performance. The software also contains 3D mechanics toolbox which provides flexibility for multibody modeling. Fig.3. Figure for kinematic analysis III. KINEMATIC ANALYSIS OF THE MECHANISM Brief kinematic analysis of hydraulic actuator based scissor lift mechanism is described in 7. In the multi stages scissor lift mechanism the moving links forms a rhombus configuration. A detailed kinematic analysis of the rhombus structure configuration and repeated rhombus structure is done by Dr. Rolland 5. The kinematic analysis for the scissor lift can be done by looking at the loops of Fig. 3. From fig. 3, = and the loop 102 forming an isosceles triangle. So, l12 = l/2 = l02 (Where l=length of each link). Input is S and output is h. Applying Pythagoras theorem: Differentiating (4) with respect to time gives the velocity. From (1) we can write another inverse relationship: By differentiating (6) with respect to time we get: The height h with respect to would be: Fig. 3 shows H =2h and the total height from Fig. 2 is 4h. Further differentiation of (5) and (7) with respect to time will give the acceleration. IV. DYNAMICS OF THE MECHANISM Dong et al. investigate the dynamic stability of scissor lift mechanism and a lumped parameter model was developed based on the dynamic characteristics resulted from the simulation 2. It was an approach based on practical work and no dynamic model was presented on the whole system. Hence this paper presents a dynamic model of the complete system which is attractive and fast compared to time and effort required by classic dynamics modeling methods. Fig.4. Schematic of a Single Link A. Bond graph Model of Each Link For bond graph modeling of a single beam a body is considered with mass and rotational inertia. External forces are applied at port A and B. Formulation become much easier when all bodies in a multibody system contains three inertial coordinate(x,y,). The velocity of the point B with respect to the point G can be formulated as: Where the point G is the center of the gravity of the link. If the distance from the point G to the point B is r then the equation will be: From the above equation the velocity component along x axis and velocity component along y axis of the point B are: To make A or B fixed we just need to apply zero flow source or approximately zero on parasitic spring in the bond graph. MTF is used in the bond graph to get the velocity constraints. Fig.4 shows the bond graph model of a single beam where length, mass and inertia parameters are considered as global parameter. Fig. 5. Bond graph of a single link B. Parasitic Stiffness and Damping To model each mechanical joint parasitic stiffness and damping are considered. Stiffness and damping are important criteria for many mechanical system designs. Stiff coupling springs are useful to use at mechanical joints to eliminate derivative causality of the system. We can use parasitic stiffness and/or resistive elements to remove dependencies among energy storage eleme