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3/6-SPS型Stewart并联机构奇异轨迹的性质识别 总被引:1,自引:1,他引:1
基于并联机构奇异位形产生的运动学原理,推导出3/6-SPS型Stewart机构奇异轨迹的解析表达式,并基于此原理提出了分析并联机构奇异位形的等效机构法,利用此方法推导出了3/6-SPS型Stewart机构处于一般姿态时在θ-平面上的奇异轨迹方程,并对其轨迹的性质进行了识别。研究结果表明,3/6-SPS型Stewart机构在相互平行的θ-平面上的奇异轨迹总是一二次多项式,包括四对相交直线、一条抛物线及双曲线束。在分析的基础上,对该并联机构处于各种姿态时的奇异轨迹的性质进行了总结。 相似文献
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Stewart并联机构位置奇异研究 总被引:1,自引:0,他引:1
对动定平台为两个非相似的半规则正六边形的Stewart并联机构位于给定姿态时的位置奇迹进行了系统地研究。基于建立该并联机构的力雅可比矩阵,推导出机构位于给定姿态时的三维位置奇异轨迹的三次符号表达式。进一步分析发现,该机构的对于给定姿态参数的三维位置奇异轨迹相当复杂,其在一般倾斜截面上的投影曲线的几何特征也很难识别。定义动平台所在平面为特征平面,研究表明在特征平面上的位置奇异轨迹曲线均是一条二次曲线,包括无数对双曲线、四对相交直线以及一条抛物线。对于个别特殊姿态,特征平面上的位置奇异轨迹二次曲线退化为平行于脊线的一对或一条直线。提出并证明关于特征平面上的位置奇异轨迹曲线几何特征的两个定理。此外,基于Grassmann线几何以及螺旋理论简要分析了位置奇异轨迹的运动学特性。 相似文献
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推导出了6/6-SPS型Stewart机构处于固定位置时机构的姿态奇异轨迹的解析表达式。研究结果表明,机构处于固定位苴时的姿态奇异轨迹是一个关于机构动平台的姿态参数的十三次多项式。还研究了机构动平台的几何外形、动平台和定平台的外接圆的半径比、动平台的位置对机构的非奇异姿态空间的影响,因此为该并联机构的优化设计提供了重要的理论依据。 相似文献
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新型三自由度并联机器人奇异位形研究 总被引:1,自引:0,他引:1
针对一种新构型的3-RRRT并联机器人奇异位形进行了研究,提出了一种建立运动学模型与研究奇异位形的方法,利用并联机器人支链中支杆的方向余弦和动平台绝对位置坐标为系统广义坐标的方法,推导了机构运动学模型和计算奇异位形的条件方程,在此基础上,提出运用浮点遗传算法和拟牛顿法相结合的混合遗传算法在MATLAB上编制奇异位形仿真程序,得到3-RRRT并机器人奇异位形分布情况,此结论对3-RRRT并联机构的运动控制及轨迹规划有重要意义. 相似文献
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作为轴对称矢量喷管转向控制驱动机构的Gough-Stewart类并联机构,主要工作在奇异位置状态.在该位置,驱动平台能够获得一个绕其法线的自由转动,导致转向控制驱动机构的运动具有不确定性.为此,采用少自由度3SPS-3PRS并联机构限制该自由转动,通过对少自由度3SPS-3PRS并联机构的分岔特性研究发现,该并联机构存在尺度极限奇异位置,且输入参数的取值对由尺度极限奇异位置决定的并联机构的工作空间影响较大.对于给定的矢量状态要求,3SPS-3PRS并联机构的输入参数变化范围有可能超出由尺度极限奇异位置确定的工作空间,导致3PRS运动链产生较大的约束内应力,同时并联机构的工作空间跨越奇异位置使得动平台在通过奇异位置后的构型具有不确定性,因此该并联机构的运动奇异性问题依然存在. 相似文献
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CAO Yi School of Mechanical Engineering Southern Yangtze University Wuxi China HUANG Zhen DING Huafeng Robotics Research Center Yanshan University Qinhuangdao China ZHOU Hui School of Mechanical Engineering Southern Yangtze University Wuxi China 《机械工程学报(英文版)》2006,19(1):41-44
The pro'blem of identifying the property of singularity loci of Gough-Stewart manipulators is addressed. After constructing the Jacobian matrix of the Gough-Stewart manipulator, a cubic polynomial expression in the mobile platform position parameters, which represents the constantorientation singularity locus of the manipulator, is derived. Graphical representations of the singularity locus of the manipulator for different orientations are illustrated with examples. Further, the singularity locus of the manipulator in the principal-section, where the mobile platform lies, is analyzed. It shows that singularity loci of the manipulator in parallel principal-sections are all quadratic expressions including a parabola, four pairs of intersecting straight lines and infinite hyperbolas. Their geometric and kinematic properties are also researched as well. 相似文献
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Cao Yi Huang Zhen Ding Huafeng 《机械设计与研究》2004,20(Z1):238-240
This paper addressed the problem of identifying the property of the singularity loci of the 6/6-Stewart manipulators. The singularity locus equation of the manipulator can be obtained by setting the determinant of the Jacobian matrix be zero. The singularity loci for different orientations are illustrated with examples. The singularity locus equation of the manipulator with respect to the oblique plane is derived either which is a polynomial expression of two degree. It shows that the singularity loci of the manipulator in the parallel oblique planes are hyperbolas accompanied with four pairs of intersecting straight lines and a parabola. Their geometric interpretations and the properties of the singularity loci are further analyzed. 相似文献
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新型6自由度3-UrRS并联机器人的奇异位形分析 总被引:3,自引:0,他引:3
研究了一种新型6自由度3支链并联机器人的奇异位形,利用机构的运动学反解方程和雅可比矩阵得出了精确的奇异位形的解析形式。从运动学角度分析,奇异位形有3类形式,每种形式都具有不同的物理意义。研究了该并联机器人的第一类和第二类奇异位形,并画出了4种特殊位置的奇异位形。奇异位形的分析对该并联机器人的轨迹规划和控制具有重要的意义。 相似文献
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Singular configurations must be avoided in path planning and control of a parallel manipulator. However, most studies rarely focus on an overall singularity loci distribution of lower-mobility parallel mechanisms. Geometric algebra is employed in analysis of singularity of a 3-RPS parallel manipulator. Twist and wrench in screw theory are represented in geometric algebra. Linear dependency of twists and wrenches are described by outer product in geometric algebra. Reciprocity between twists and constraint wrenches are reflected by duality. To compute the positions of the three spherical joints of the 3-RPS parallel manipulator, Tilt-and-Torsion angles are used to describe the orientation of the moving platform. The outer product of twists and constraint wrenches is used as an index for closeness to singularity(ICS) of the 3-RPS parallel manipulator. An overall and thorough perspective of the singularity loci distribution of the 3-RPS parallel manipulator is disclosed, which is helpful to design, trajectory planning and control of this kind of parallel manipulator. 相似文献
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Reciprocal screw theory based singularity analysis of a novel 3-DOF parallel manipulator 总被引:2,自引:2,他引:0
Singularity analysis is an essential issue for the development and application of parallel manipulators.Most of the existing researches focus on the singularity of parallel manipulators are carried out based on the study of Jacobian matrices.A 3-DOF parallel manipulator with symmetrical structure is presented.The novel parallel manipulator employs only revolute joints and consists of four closed-loop subchains connecting to both base and platform via revolute joints.The closed-loop subchain in each chain-leg is a spherical 6R linkage.The motion characteristics of the output link in the spherical 6R linkage with symmetrical structure are analyzed based on the interrelationships between screw systems.The constraints that are exerted on the platform by each chain-leg are investigated applying the concept of generalized kinematic pair in terms of equivalent screw system.Considering the geometric characteristics of the parallel manipulator,the singularity criteria of the parallel manipulator corresponding to different configurations are revealed based on the dependency of screw system and line geometry.The existing conditions of certain configuration that a singularity must occur are determined.This paper presents a new way of singularity analysis based on disposition of constraint forces on the geometrically identified constraint plane and the proposed approach is capable of avoiding the complexity in solving the Jacobian matrices. 相似文献
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郑德星 《机械制造与自动化》2012,41(2):41-43,49
针对观察法无法确定少自由度并联机构的活动能力问题,对所研究的3 - PUU机构进行了运动学建模,求解了机构的速度Jacobi矩阵,采用代数法借助Jacobi矩阵的秩分析了机构的奇异性,绘制了详细的判别表格.研究表明,运动中机构的奇异性与z坐标的位置无关,考虑机构的具体尺寸、工作要求和安装位型,该3 - PUU机构在特定的工作空间内是不存在奇异的. 相似文献
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针对一种六棱锥式新型并联机器人的轨迹规划问题,基于具有反解选取准则的机构逆运动学方程,对奇异性和工作空间进行深入研究。由雅可比矩阵提出机构奇异判别方程,并引入可操作度性能指标进行奇异性分析。考虑运动副范围以及连杆干涉等约束条件,采用三维边界搜索法,给出机构在定姿态下工作空间的三维可视化描述。进行边界采样实验,实验结果表明了仿真的正确性。研究结果可为无奇异轨迹规划提供理论依据。 相似文献
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Singularity analysis is an important issue in the design of parallel manipulators, since they become uncontrollable at singular
configurations due to the rank deficiency of the Jacobian. This paper analyzes the singularity of a double parallel manipulator
with respect to its workspace. The workspace is decoupled into a positional workspace generated by the first parallel mechanism,
and an orientational workspace by the second mechanism. The singularities occurring outside each workspace are analytically
found by a Jacobian matrix derived for the velocity transformation from the end-effecfor to the linear actuators. The singularity
loci are presented and their geometric properties are examined to prove that the double parallel manipulator is free from
the singularity problem. 相似文献