【作者】 张帆；

【导师】 杨建国；

【作者基本信息】 东华大学 ， 机械制造及其自动化， 2008， 博士

【摘要】 并联机构的静刚度大、动力响应迅速等优点,使其在金属切削机床、工业自动化、医疗设备等领域具有广泛的应用前景;然而,并联机构在运动学、动力学等方面上的复杂特性使它在实际应用遇到许多困难。因此,改善并联机构的运动学、动力学等性能,使设计的并联机构能够很好满足工程实际的需要,成为并联机构应用研究中亟待解决的问题之一。本文对并联机构瞬时运动、奇异位形、运动解耦、全局各向同性等问题进行了研究,主要研究内容包括:(1)在回顾并联机构研究现状基础上,对现有并联机构特性分析及综合研究进行了总结,分析并联机构研究中取得的成果和存在的不足,论述了本文研究并联机构瞬时运动、奇异位形等问题的意义和具体内容。(2)针对并联机构的多支链闭环的结构特点,提出一种基于螺旋理论的空间机构学的分析方法,将并联机构分为运动支链与动平台两个组成部分,根据运动支链末端对动平台的作用力,分析并联机构瞬时运动、奇异位形等问题。(3)利用约束螺旋与运动螺旋的几何规律,提出了并联机构瞬时运动分析的几何方法(IMGA),并得到主动避免瞬时运动的并联机构设计准则,建立了通过拓扑优化手段综合避免瞬时运动并联机构的方法。基于以上方法,综合得到一些结构新颖的、避免瞬时运动的两转动一移动并联机构。(4)利用螺旋线性相关的几何特征,提出主动避免并联机构奇异位形并联机构设计准则,建立了通过拓扑优化手段综合避免奇异位形并联机构的方法。基于以上方法,综合得到结构新颖的、避免奇异的三转动3-RRR并联机构和两转动一移动2RPS-PS并联机构。(5)利用运动支链末端作用力理论,推导出解耦并联机构的设计准则,建立了通过拓扑优化手段综合解耦并联机构的方法。基于以上方法,综合得到了解耦的一转动两移动并联机构,三移动并联机构。其中解耦的一转动两移动并联机构是新颖机构。(6)鉴于一般并联机构静刚度存在上下限,证明了全局各向同性并联机构工作空间内静刚度全局相同,进一步得到全局各向同性并联机构的设计准则,建立了通过拓扑优化手段综合全局各向同性并联机构的方法。基于以上方法,综合得到了全局各向同性的两移动并联机构和三转动并联机构。更多还原

【Abstract】 The parallel mechanism which is famous of the advantages of high stiffness,the heavy loader,quick response has wide potential application in metal-cutting machine tools,industry automation and medical instrument fields.However,the complex kinematics and dynamics of parallel mechanism make it very hard to use parallel mechanism in practical application.Thus,the most urgent problem of parallel mechanism research is to optimize the kinematics and dynamics performance of parallel mechanism to satisfy the practical need.The thesis focused on instantaneous motion,singularity,decoupled mechanism and full-isotropic mechanism.The main work of the thesis includes:(1) The research of parallel mechanism is reviewed.The performance analysis and type synthesis of parallel mechanism is summarized,and the problem existed is also presented.The significances of research on instantaneous motion,singularity and coupled motion problems are proposed.(2) A novel approach of spatial mechanism based on screw theory is proposed, according to the multiple closed-loop structure characteristics of parallel mechanism. The parallel mechanism can be divided into two parts:kinematic chains and moving-platform,and the internal forces between kinematic chains and moving-platform,which can be calculated by screw theory according to the structure of parallel mechanism,are used to analyze instantaneous motion,singularity and coupled motion problems.(3) Based on the geometric features between constraint wrench and motion twist, the design principle of instantaneous motion-free parallel mechanism is proposed. Based on the principle,a number of novel two rotational and one translational Dofs parallel mechanisms are found.(4) Based on the geometric features of linear-related screws,the design principle of singularity-free parallel mechanism is proposed.Based on the principle,a novel three rotational Dofs 3-RRR parallel mechanism and a two rotational and one translational Dofs 2RPS - PS parallel mechanism are presented. (5) Based on the constraint force of kinematic chains,which can be calculated from the structure of the given parallel mechanism,the design principle of decoupled parallel mechanism is proposed.Based on the principle,a number of novel decupled one rotational and two translational Dofs parallel mechanisms are found.(6) The parallel mechanisms with homogeneous stiffness are found,and these special parallel mechanisms are proved to be full-isotropic parallel mechanisms, according to the stiffness matrix of parallel mechanism.The type synthesis method of full-isotropic parallel mechanism is obtained,and some two translational Dofs parallel mechanisms and three rotational Dofs mechanisms are synthesized.更多还原