共查询到20条相似文献,搜索用时 31 毫秒
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大型机械结构的分层动态优化方法 总被引:1,自引:0,他引:1
针对大型机械结构动态优化设计维数高,同时涉及外形尺寸和截面尺寸两类变量,采用整体优化策略,存在收敛困难的问题,提出了采用分层优化结合子结构方法的机械结构动态优化策略。以有限元方法为基础,将外形尺寸和截面尺寸分离到两个相对独立的设计空间,从而将整体优化问题分解为整体层优化和局部层优化两个子优化问题。在整体层以整体结构动态特性最优为目标,完成对外形尺寸的优化;在局部层以子结构动态特性最优为目标,完成对截面尺寸的优化;两层优化交替进行直至问题最后收敛。某型大跨自动扶梯金属结构的动态优化工程实例表明,该方法优化效果良好且优化效率高。 相似文献
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Hakgu Kim Kwangseok Oh Kyungeun Ko Panyoung Kim Kyongsu Yi 《Journal of Mechanical Science and Technology》2016,30(2):603-610
This paper presents a wheel loader simulation model, validation results and energy flow analysis. The developed simulation model will facilitate the performance evaluation and optimization process in the development stage of a prototype wheel loader. The wheel loader simulation model consists of mechanical and hydraulic powertrain model, multi-body dynamic model and working part dynamic model. The multi-body dynamic model is simplified since the effect of pitch and roll motion of the wheel loader on the energy flow of the powertrain and hydraulic actuator systems is insignificant, a simplified planar model for the dynamic vehicle is good enough for the objective of this study. Every component is modeled and integrated in a simulation package developed using Matlab/Simulink. The simulation model has been validated using experiment data and the validation results show that it effectively represents the actual dynamic characteristic of the target wheel loader. The verified simulation model will be used as a virtual platform to evaluate the performance of alternative powertrain models such as a dual-clutch transmission and hydrostatic transmission. An advanced control system can also be implemented and evaluated using the virtual platform. 相似文献
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针对同时具有被动关节和柔性杆的欠驱动平面机械臂,提出一种简单易行的分段位置控制策略。以2R欠驱动平面柔性机械臂为研究对象,建立机械臂的假设模态动力学模型,分析系统的动力学耦合特性与可控性。通过被动关节处制动器的开闭切换,研究平面柔性机械臂的分段位置控制策略,采用PID方法分别设计各阶段主动、被动关节的控制算法。最后,基于自行开发的欠驱动平面机械臂的试验平台及实时控制系统,完成了2R欠驱动平面柔性机械臂位置控制的试验研究。仿真和试验结果表明,主动关节和被动关节在各阶段都能很好地跟踪目标值,进而实现机械臂的操作任务,验证了所提控制方法的可行性和有效性,以及欠驱动柔性机械臂动力学模型的正确性。 相似文献
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In recent years, various cable-driven parallel robots have been investigated for their advantages, such as low structural weight, high acceleration, and large workspace, over serial and conventional parallel systems. However, the use of cables lowers the stiffness of these robots, which in turn may decrease motion accuracy. A linear quadratic (LQ) optimal controller can provide all the states of a system for the feedback, such as position and velocity. Thus, the application of such an optimal controller in cable-driven parallel robots can result in more efficient and accurate motion compared to the performance of classical controllers such as the proportional-integral-derivative controller. This paper presents an approach to apply the LQ optimal controller on cable-driven parallel robots. To employ the optimal control theory, the static and dynamic modeling of a 3-DOF planar cable-driven parallel robot (Feriba-3) is developed. The synthesis of the LQ optimal control is described, and the significant experimental results are presented and discussed. 相似文献
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Connection Method for Dynamic Modelling and Simulation of Parallel Kinematic Mechanism (PKM) Machines 总被引:2,自引:0,他引:2
Q. Huang H. Hådeby G. Sohlenius 《The International Journal of Advanced Manufacturing Technology》2002,19(3):163-173
The design of a PKM (parallel kinematic mechanism) machine usually concentrates on a kinematic analysis but its dynamic control
behaviour is not paid equal attention, so there is a need to model a PKM machine dynamically. This paper presents a connection
method for dynamic modeling of a PKM machine by introducing active and passive matrices. Using computer algebra, this method
makes the dynamic modeling processes available, even though the kinematic constraint Eq. cannot be solved as analytical solutions.
The modeling is used succesfully for a planar PKM machine, called PAMELA (parallel mechanism with linear actuators). Using
dynamic modeling and simulation, we can anticipate the dynamic behaviour of the PAMELA machine and develop a suitable algorithm
for the motion control. This enables a better dynamic configuration of the PAMELA machine to be obtained. As a consequence,
it speeds up the design process and reduces the development cost before a physical machine is built.
RID="
ID=" <E5>Correspondence and offprint requests to</E5>: Dr Q. Huang, Department of Manufacturing Systems, The Royal Institute
of Technology, 100 44 Stockholm, Sweden. E-mail: qhu@cadcam.kth.se 相似文献
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ON THE DYNAMIC MODELING AND CONTROL OF 2-DOF PLANAR PARALLEL MECHANISM WITH FLEXIBLE LINKS 总被引:1,自引:0,他引:1
Luo Lei Wang Shigang Mo Jinqiu Cai Jianguo School of Mechanical Engineering Shanghai Jiaotong University Shanghai China 《机械工程学报(英文版)》2005,18(1):112-117
The object of study is about dynamic modeling and control for a 2 degree-of-freedom (DOF) planar parallel mechanism (PM) with flexible links. The kinematic and dynamic equations are established according to the characteristics of mixed rigid and flexible structure. By using the singular perturbation approach (SPA), the model of the mechanism can be separated into slow and fast subsystems. Based on the feedback linearization theory and input shaping technique, the large scale rigid motion controller and the flexible link vibration controller can be designed separately to achieve fast and accurate positioning of the PM. 相似文献
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为了实现对基因测序仪运动平台的高精度定位控制,建立了基因测序仪运动平台控制系统。对该系统所采用的数学建模、模型辨识、控制器设计、输入整形等方法进行研究。根据运动平台动力学方程和永磁同步直线电机电压-推力关系构建了运动平台数学模型,利用频域扫描法在实物实验的基础上辨识出运动平台的模型参数。最后,基于运动平台模型设计了双闭环控制器和前馈控制器组成的复合控制器来保证运动平台的稳定性和高精度,同时根据整个系统的主导极点设计了输入整形器以抑制运动平台的残余振荡。实验结果表明:加入了输入整形的复合控制器将运动平台的稳态重复定位精度从±1.47μm提高到±0.354μm。较传统复合控制器,本文提出的方法能使基因测序仪运动平台更快进入可用重复定位精度范围,并基本满足基因测序仪采集图像时所需的稳定性强、精度高等要求。 相似文献
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Yixu Song Jianfa Wang Kaiming Yang Wensheng Yin Yu Zhu 《The International Journal of Advanced Manufacturing Technology》2010,48(5-8):633-643
Modern manufacturing equipment often requires high-speed and ultra-precise linear motion. For implementing such motion, a coarse–fine dual stage is effective because the coarse stage has a low bandwidth with a large workspace, and in contrast, the fine stage has a high bandwidth with a small stroke. This paper presents the implementation of an air-bearing, dual-stage system and its control strategy. A closed-loop feedback in an absolute space is used to realize coarse–fine control. The fine stage is driven by a voice coil motor that tracks the designed trajectory, while the coarse stage is driven by permanent-magnet linear synchronous motor that tracks the trajectory of the fine stage to prevent its motion saturation. Also analyzed are the coupled dynamics of the air-bearing dual stage driven by a direct-drive motor. Identification and robust control design for the fine stage are introduced in detail. Method tests for the single fine stage are performed, and the results demonstrate that ultra-precision control can be realized for the fine stage. Next, experiments are presented with the dual stage using different loads. Experimental results show that our control strategy can achieve high-speed, ultra-precision linear motion through the dual stage with a satisfactory performance. 相似文献
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蛇形机器人动力学建模的虚设机构法 总被引:1,自引:0,他引:1
基于应用影响系数和虚功原理,通过虚设动力机构提出一种蛇形机器人动力学建模方法,导出考虑骨节侧向滑动条件下的蛇形机器人二阶非完整约束方程。应用这种方法无需进行繁琐的求导或消元运算,可直接基于所给公式编程进行蛇形机器人正逆双向动力学仿真,从而为研究蛇形机器人的动力耦合特征和开发具有二阶非完整约束的蛇形机器人的运动控制器,提供一种实用有效的方法。该方法不仅适于平面运动蛇形机器人,还可进一步推广实现空间运动的蛇形机器人的动力学建模与仿真。 相似文献
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对二维工作台控制系统进行了研究,采用滚珠丝杆副和直线滚动导轨副的传动方式,选用直线光栅尺作为工作台的反馈元件,控制系统的核心为工控机和运动控制卡,利用固高GE400运动控制卡发出脉冲信号控制伺服驱动器对工作台机械部分进行实时的操控。在VC++6.0设计环境下开发工作台的控制软件,实现了多轴控制。使用双频激光仪获得工作台的系统误差曲线,采取水平分割的方法对误差曲线进行分割,获得各区间的误差补偿数据,通过软件控制对工作台各行程区间进行误差补偿,通过理论计算和实验测得补偿后的数据对比,验证了该补偿方法的可靠性,对于提升二维工作台的精度具有积极的意义。 相似文献
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数控非接触式超光滑光学元件加工机床的设计 总被引:1,自引:0,他引:1
基于数控技术,提出了一种非接触式光学元件表面超光滑液体抛光方法.通过磨头中心孔为抛光表面提供抛光液,抛光液在磨头自转的带动下与光学元件表面相互作用,实现光学元件表面材料的微量去除,利用计算机控制抛光磨头的运动轨迹完成对光学元件表面的抛光.根据上述原理,设计和研制了数控非接触表面超光滑光学元件加工机床样机,样机直线运动轴最低进给速度为0.000 1 m/s,定位精度为0.008 mm;摆动轴最低转速为0.002 8 r/min,定位精度为15″.抛光实验结果表明,经过20 min的超光滑加工,熔石英材质光学元件上两点的表面粗糙度Ra值分别由加工前的1.03 nm和0.92 nm提高到加工后的0.48 nm和0.44 nm,显著提高了加工精度. 相似文献
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Chengyuan LIANG Fang YUAN Xuedong CHEN Wei JIANG Lizhan ZENG Xin LUO 《Frontiers of Mechanical Engineering》2019,14(3):255
Nano-precision positioning stages are characterized by rigid-flexible coupling systems. The complex dynamic characteristics of mechanical structure of a stage, which are determined by structural and dynamic parameters, exert a serious influence on the accuracy of its motion and measurement. Systematic evaluation of such influence is essential for the design and improvement of stages. A systematic approach to modeling the dynamic accuracy of a nano-precision positioning stage is developed in this work by integrating a multi-rigid-body dynamic model of the mechanical system and measurement system models. The influence of structural and dynamic parameters, including aerostatic bearing configurations, motion plane errors, foundation vibrations, and positions of the acting points of driving forces, on dynamic accuracy is investigated by adopting the H-type configured stage as an example. The approach is programmed and integrated into a software framework that supports the dynamic design of nano-precision positioning stages. The software framework is then applied to the design of a nano-precision positioning stage used in a packaging lithography machine. 相似文献
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引线键合采用高纯度金线、铝线连接电子晶片和外围的管脚,是标准的微电子加工和封装的技术。从引线键合运动的角度来说,完整过程包括两种不同的运动状态:自由运动和约束运动。因为系统状态的不连续,在从自由运动的非接触状态到约束运动的接触状态时的阶跃过程,过大的键合力导致“过键合”情况,造成引线键合球的龟裂。所以,引线键合的质量和可靠性很大程度上取决于键合力控制的性能。很多因素都对键合力控性能有很大的影响。在本文中,提出一个具有鲁棒性优化的方法,用来设计高性能的键合力控制系统,在系统参数的波动和不确定性对于性能的影响的情况下,实现引线键合的平滑、稳定的接触阶跃控制。两步走的策略被采用:第一步,建立键合力控制系统的闭环模型;第二步,控制和结构同步鲁棒性优化,设计出高性能的键合力控制系统。 相似文献
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D. Tong S. C. Veldhuis M. A. Elbestawi 《The International Journal of Advanced Manufacturing Technology》2007,33(3-4):379-388
A dual stage feed drive system is well suited to satisfying current demands of high performance machining with tight position
control under high feed rates in the presence of disturbances. It does this by integrating an actuator with high position
resolution and fast response together with a conventional linear drive. A magnetostrictive actuator (MA) with a bandwidth
in the kHz range capable of several kN of force output is an ideal candidate for use as the fine positioning element in such
a dual stage system. However, MAs display significant hysteresis in their performance. This makes the effective implementation
of real-time fast servo control challenging. In this paper, a dynamic Preisach model is utilized to reduce the undesired nonlinearity.
A sliding mode controller (SMC) is designed to deal with uncertainties such as the Preisach modeling error as well as external
disturbances so as to ensure a robust stable system. Experimental results show the servo performance improvement during a
feed step test for single axis control and a single axis component of a sharp path interpolation test. 相似文献
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Transient dynamics of tapping mode atomic force microscope (AFM) for critical dimension measurement are analyzed. A simplified nonlinear model of AFM is presented to describe the forced vibration of the micro cantilever-tip system with consideration of both contact and non-contact transient behavior for critical dimension measurement. The governing motion equations of the AFM cantilever system are derived from the developed model. Based on the established dynamic model, motion state of the AFM cantilever system is calculated utilizing the method of averaging with the form of slow flow equations. Further analytical solutions are obtained to reveal the effects of critical parameters on the system dynamic performance. In addition, features of dynamic response of tapping mode AFM in critical dimension measurement are studied, where the effects of equivalent contact stiffness, quality factor and resonance frequency of cantilever on the system dynamic behavior are investigated. Contact behavior between the tip and sample is also analyzed and the frequency drift in contact phase is further explored. Influence of the interaction between the tip and sample on the subsequent non-contact phase is studied with regard to different parameters. The dependence of the minimum amplitude of tip displacement and maximum phase difference on the equivalent contact stiffness, quality factor and resonance frequency are investigated. This study brings further insights into the dynamic characteristics of tapping mode AFM for critical dimension measurement, and thus provides guidelines for the high fidelity tapping mode AFM scanning. 相似文献
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《机械与工业》2002,3(2):173-180
High speed machining and working (HSMW) machine tools have to reach a given performance level in terms of precision and static and dynamic stiffness. Their dimensioning requires the consideration of flexibilities as well as adopted control strategy. In this article we present an approach for dynamic modeling of flexible mechanisms in the aim of their control and dimensioning for HSMW applications. To formulate the kinematic model of a flexible manipulator, infinitesimal displacement operators are used. Infinitesimal displacement terms, of order greater than 1, are systematically neglected. Therefore, equations of motion are derived using Lagrange formalism. The proposed approach allows one to handle both cases of distributed and lumped flexibilities. The importance of taking into account flexibility is illustrated by simulation results, for HSMW machine prototype with parallel kinematic architecture, in the case of lumped flexibilities. 相似文献