Statics and stiffness of 3 DOF parallel loading mechanism
-
摘要: 基于螺旋理论建立了用于数控机床随动加载的3自由度并联机构的静力学方程,得到机构的驱动力与动平台所受外载的映射关系,方程考虑了支链重力对静力学模型的影响,通过算例绘制了在指定载荷下机构驱动力在工作空间内的分布曲线图.在考虑支链重力和在约束力下支链弹性变形对刚度影响的情况下,建立了机构的静刚度模型,分析了给定静载荷条件下机构在定姿态空间内的变形分布情况,并评价了机构的刚度性能,结果表明机构的刚度特性关于y轴对称且在工作空间的边界刚度变差.Abstract: A static model of a 3-DOF parallel mechanism (PM) that is used for computerized numerical control (CNC) machine tool follow-up loading test was established based on the screw theory. The mapping between actuation force and loading force of the moving platform was built considering the influence of limbs' weight. Then the distribution of actuation forces in workspace under specified loads was analyzed through a numerical example. Moreover, the static stiffness mapping model of the PM was established. The model considers influences of the limbs' weight and the parts' elastic deformation under the constraint force. At last the deformation of the PM in the workspace under given static loads was analyzed and the stiffness characteristic was evaluated. The results show that the distribution of stiffness in workspace is symmetrical about the y-axis and the stiffness will be worsened when it comes near the workspace boundary.
-
Key words:
- parallel mechanism /
- statics /
- elastic deformation /
- static stiffness /
- stiffness characteristic
-
[1] Huang T, Wang J S, Whitehouse D J.Closed form solution to the workspace of hexapod based parallel machine tools[J].ASME J of Mechanical Design, 1999, 121(1):26-31 [2] 尹小琴, 马履中, 杨启志.并联机构静力学分析[J].农业机械学报, 2007, 38(12):201-203 Yin Xiaoqin, Ma Lüzhong, Yang Qizhi. Statics analysis of paral-lel mechanism[J].Transactions of the Chinese Society for Agricultural Machinery, 2007, 38(12):201-203(in Chinese) [3] Tsai L W. Robot analysis:the mechanics of serial and parallel manipulators[M].New York:John Wiley & Sons, 1999 [4] 徐东涛, 孙志礼, 丁晓光.考虑杆件弹性变形的改进型Delta并联机构刚度特性分析[J].农业机械学报, 2013, 44(5):294-298 Xu Dongtao, Sun Zhili, Ding Xiaoguang.Stiffness characteristic analysis of modified Delta parallel mechanism based on bars' elastic deformation[J].Transactions of the Chinese Society for Agricultural Machinery, 2013, 44(5):294-298(in Chinese) [5] Portman V T, Chapsky V S, Shneor Y.Workspace of parallel kinematics machines with minimum stiffness limits:collinear stiffness value based approach[J].Mechanism and Machine Theory, 2012, 49:67-86 [6] Gosselin C. Stiffness mapping for parallel manipulators[J].IEEE Transactions on Robotics and Automation, 1990, 6(3):377-382 [7] 李树军, Clement G.3-RRR平面并联机构的刚度特性分析[J].东北大学学报:自然科学版, 2007, 28(1):91-94 Li Shujun, Clement G. Stiffness analysis and stiffness mapping of 3-RRR planar parallel mechanism based on CCT stiffness matrix[J].Journal of Northeastern University:Natural Science, 2007, 28(1):91-94(in Chinese) [8] 赵铁石, 赵延治, 边辉, 等.空间并联机构连续刚度非线性映射[J].机械工程学报, 2008, 44(8):20-25 Zhao Tieshi, Zhao Yanzhi, Bian Hui, et al.Continuous stiffness nonlinear mapping of spatial parallel mechanism[J].Chinese Journal of Mechanical Engineering, 2008, 44(8):20-25(in Chinese) [9] Wu J, Wang J S, Wang L P, et al.Study on the stiffness of a 5-DOF hybrid machine tool with actuation redundancy[J].Mechanism and Machine Theory, 2009, 44(2):289-305 [10] 李永刚, 宋轶民, 黄田.少自由度并联机器人机构的静力分析[J].机械工程学报, 2007, 43(9):80-83 Li Yonggang, Song Yimin, Huang Tian.Static force analysis of lower-mobility parallel manipulators[J].Chinese Journal of Mechanical Engineering, 2007, 43(9):80-83(in Chinese) [11] 崔学良. 冗余驱动支链对并联机构性能的改善及其控制方法研究[D].北京:北京航空航天大学, 2010 Cui Xueliang.Research on the improvement in the capabilities of the parallel machine with the redundant leg and the control method[D].Beijing:Beijing University of Aeronautics and Astronautics, 2010(in Chinese) [12] Rezaei A, Akbarzadeh A, Akbarzadeh-T M R.An investigation on stiffness of a 3-psp spatial parallel mechanism with flexible moving platform using invariant form[J].Mechanism and Machine Theory, 2012, 51:195-216
点击查看大图
计量
- 文章访问数: 1147
- HTML全文浏览量: 127
- PDF下载量: 558
- 被引次数: 0