【作者】 朱春霞；

【导师】 刘永贤； 蔡光起；

【作者基本信息】 东北大学 ， 工业工程， 2008， 博士

【摘要】 并联机床因其为闭环机构链,理论上具有刚度好、精度高和配置多样等优势,在制造领域具有很广泛的应用前景。目前世界各国对并联机床的研发总体上仍处研究、试制和试用阶段。与国外相比,国内对并联机床理论、设计与应用等方面的关键技术研究仍有较大差距。因此,如何利用现有技术有效的分析机构运动学、动力学性能、运动控制等关键技术问题,并对机床的工作能力进行合理评价,成为并联机床研究中一个亟待解决的问题。由于并联机床的整体布局具有多样性,其动态特性、工作空间的大小和形状、运动参数等有很大的差异性,因此建模、仿真和虚拟现实技术是并联机床设计过程中不可缺少的环节,它涉及到并联机床机构学、运动学、零件建模、三维实现和运动控制等关键技术,是一项综合性的有创新意义和使用价值的研究课题。本文在前人研究的基础上,以一种3-TPT型并联机床为例,将新兴的虚拟样机技术应用到并联机床的关键技术的创新研究中,对其虚拟样机模型的建立、运动学、工作空间的求解,多柔体系统动力学,动态特性、机电系统的联合仿真以及误差等关键技术进行了研究分析和仿真,为并联机床实现高效的现代设计研究做了有意义的尝试,全文的主要研究内容如下：(1)论述了本课题研究的背景以及并联机床国内外发展的历史和现状,总结了并联机床当今的关键技术进展及发展趋势,综述了虚拟样机技术的发展概况,论证了将虚拟样机技术引入到并联机床进行设计开发的前沿性。(2)对3-TPT并联机床进行了机构分析,利用螺旋理论求取了机构的反螺旋系来判断机构受到的约束数和机构存在的自由度,同时对机构输入选取的合理性及机构的运动特性进行了研究,解出了机构可能实现和被约束掉的螺旋运动。(3)利用ADAMS软件与三维建模软件的转换功能,建立了3-TPT并联机床的虚拟样机模型,并对其动力学进行了分析和仿真研究。提出了利用虚拟样机技术求解工作空间的思路,得到了3-TPT并联机床的工作空间图形,同时通过与解析法对比,说明了利用虚拟样机技术求解工作空间的方法简单可行。(4)对3-TPT并联机床多柔体系统的动力学进行了研究,推导出了其多柔体系统的动力学方程。利用虚拟样机软件ADAMS和有限元软件ANSYS联合仿真的方法对其进行了分析,同时将仿真的载荷加载到柔性杆件上进行了应力分析,找出了柔性杆件的薄弱环节,并给出了优化意见。(5)利用虚拟样机技术仿真和实验模态分析两种方法,从仿真和实验两个方面研究了3-TPT并联机床的动态特性,并通过实验所测结果验证了仿真结果的可靠性。(6)对3-TPT并联机床的伺服控制原理以及其动力学耦合特性进行了分析,利用MATLAB软件建立其控制系统的流程图,通过其输出来驱动控制ADAMS中的虚拟样机机械系统,从而建立了并联机床机电系统的联合仿真平台,并通过对控制输入和输出结果的分析,来判断控制系统的优劣。(7)对并联机床的误差进行了详细的分析,分别依照矩阵法和矢量综合法以及误差独立作用原理建立了3-TPT并联机床的误差模型。利用虚拟样机技术对机床运动过程中杆件柔性所产生的误差对刀具轨迹的影响进行了仿真分析,总结了其影响规律。最后给出了误差补偿的方法。虚拟样机技术可以在机械设计完成后不必制作物理样机,仅通过计算机建立的机械系统的三维实体模型和力学模型就可对产品的性能进行分析和评估,为产品的设计和制造提供参考依据。本文采用虚拟样机技术有效地实现了并联机床的建模和仿真,这种方法不只是适用于并联机床的设计开发,还可以推广到其它一些复杂机械系统的研究、设计和开发,因此本文的研究方法和结论具有重要的实用价值。更多还原

【Abstract】 The parallel machine tool (PMT) has some advantages such as good stiffness, high precision and various layouts in theory due to its closed loop mechanism chain, so it has expensive applied prospect in manufacturing domain. At present, the study and development of PMT in every country of the world are still at a stage of research and trial production. Compared with foreign countries our country still has a long way to go to study the key techniques of PMT like theory, design and application. Therefore, how to effectively analyze the key techniques and rationally evaluate the working capacity of PMT became an urgently problem. Because the layout of PMT possesses variety and the dynamic characteristic, size and shape of workspace and motion parameters are all different, modeling, simulation and virtual reality techniques are indispensable. They refer to the key techniques like mechanism, kinematics, parts modeling, three dimensional realization and motion control and so on. So it is a comprehensive study subject with innovation and use value.This dissertation applies the virtual prototype technique on key techniques of PKM based on former research outcome and takes a 3-TPT PMT as an example, analyzes and simulates its key techniques such as virtual prototype model, kinemics, workspace, flexible multibody dynamics, dynamic characteristic, co-simulation of electronic system and error. It is a significative attempt for realizing high efficient modern design and research. The specific content as follows:(1) The background of the study and the developing history and current situation of PMT are discussed. Both the progress and trend of the key techniques of PMT are summarized. Then the development general situation of virtual prototype technique is surveyed. At last the forward position of applying the virtual prototype on design and development of PMT is demonstrated.(2) The mechanism of 3-TPT PMT is analyzed, the reciprocal screw system of the mechanism for judging the constraints and three freedoms of degree are derived by screw theory, and then the rational input choices and main screw of mechanism of 3-TPT PMT is educed, at last the screw motions which may be realized or restrained are solved. These studies can be used for instructing building the virtual prototype model of PMT. (3) The virtual prototype model of 3-TPT is built by the interface between ADAMS and other 3-D software, and its kinematics is analyzed and simulated. Then the thought for resolving workspace with virtual prototype technique is put forward. The results of workspace graphics are got in ADAMS. This method is simple and feasible compared with analytical method.(4) The flexible multibody dynamics of 3-TPT PMT is studied and its dynamic equations are educed. Then the co-simulation by ADAMS and ANSYS is proposed, and the the simulation loads are loaded on the flexible links to carry out the stress analysis for finding out the weakness link of flexible links, after that the optimization plan is given.(5) The dynamic characteristic of 3-TPT PMT is studied by using virtual prototype simulation and modal experiment. The experiment results are used for testing the simulation results.(6) The control system and dynamics coupling characteristic of 3-TPT PMT are analyzed, then its flowchart of control system is built in MATLAB to drive the mechanism system in ADAMS, so the the co-simulation platform is built. It can be used for judging the control system is good or bad.(7) The error of PMT is analyzed in detail, and the error models of 3-TPT PMT are separately built by uniting matrix and vector methods and error independence principle, the effect factors are also analyzed. The errors caused by flexible links when machine tool moving are simulated by virtual prototype technique, and its effect laws are summarized. At last the error compensation methods are given.The physics prototype needn’t to be made after design when using the virtual prototype technique. The evaluation and analysis of performance of products can be carried out by the tree dimensional model and mechanics model of mechanical system built by computer, it can provide the reference for design and manufacturing of products. This dissertation effectively realizes modeling and simulation by virtual prototype technique, the method not only suits the study, design and development of PMT but also other complex mechanism system, so the study method and conclusions have important practical value.更多还原