考虑间隙和构件柔性的3-RRR机构运动精度分析
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摘要
在考虑运动副间隙和构件柔性的情况下,对3-RRR并联机构的运动精度进行分析。计入能量损耗和摩擦力变化,构建了含间隙转动副的接触力模型,并利用ANSYS关于柔性体转化的方法描述构件的柔性,在ADAMS中建立该机构的虚拟样机模型。并利用该模型对比不同间隙值下动平台中心运动的位移及速度。引入量纲一参数对间隙尺寸、动平台转速和构件柔性的影响进行评估,对3-RRR机构运动精度进行定量分析。结果表明:在3-RRR机构中,间隙值越大,动平台的运动精度越低;相较刚性构件,采用柔化模型时动平台速度误差有所下降;输入转速的增大会使动平台速度误差显著增大。
The kinematic accuracy of 3-RRR parallel mechanism was analyzed considering joint clearances and flexible components. The contact force model of revolute joints with clearance was built by taking the energy loss and the friction into account. After modelling the flexible components in 3-RRR mechanism via ANSYS, the virtual prototype of mechanism was constructed on the ADAMS platform. By using this virtual model, the displacements and velocities of center of moving platform were calculated and compared with different sizes of the joint clearance. In order to quantitatively analyze the kinematic accuracy of 3-RRR mechanism, some dimensionless parameters were introduced to further evaluate the influences of the clearance size, rotational speed, and flexibility of components. The results show that the kinematic accuracy decreases with increasing of size of joint clearance in the 3-RRR mechanism. Comparing to rigid components, the velocity error of the moving platform of mechanism with flexible components also decreases. The increase of the input rotational speed enlarges the velocity error of the moving platform remarkably.
The kinematic accuracy of 3-RRR parallel mechanism was analyzed considering joint clearances and flexible components. The contact force model of revolute joints with clearance was built by taking the energy loss and the friction into account. After modelling the flexible components in 3-RRR mechanism via ANSYS, the virtual prototype of mechanism was constructed on the ADAMS platform. By using this virtual model, the displacements and velocities of center of moving platform were calculated and compared with different sizes of the joint clearance. In order to quantitatively analyze the kinematic accuracy of 3-RRR mechanism, some dimensionless parameters were introduced to further evaluate the influences of the clearance size, rotational speed, and flexibility of components. The results show that the kinematic accuracy decreases with increasing of size of joint clearance in the 3-RRR mechanism. Comparing to rigid components, the velocity error of the moving platform of mechanism with flexible components also decreases. The increase of the input rotational speed enlarges the velocity error of the moving platform remarkably.
引文
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[2] FLORES P,KOSHY C S,LANKARANI H M,et al.Numerical and Experimental Investigation on Multibody Systems with Revolute Clearance Joints[J].Nonlinear Dynamics,2011,65(4):383-398.
[3] 尉立肖,刘才山.圆柱铰间隙运动学分析及动力学仿真[J].北京大学学报(自然科学版),2005,41(5):679-687.YU L X,LIU C S.Dynamic Simulation and Kinetic Description of Revolute Joint with Spatial Clearance[J].Acta Scientiarum Naturalium Universitatis Pekinensis,2005,41(5):679-687.
[4] 高名旺,张宪民,刘晗.3-RRR高速并联机器人运动学设计与实验[J].机器人,2013,35(6):716-722.GAO M W,ZHANG X M,LIU H.Experiment and Kinematic Design of 3-RRR Parallel Robot with High Speed[J].Robot,2013,35(6):716-722.
[5] ZHANG X C,ZHANG X M,CHEN Z.Dynamic Analysis of a 3-RRR Parallel Mechanism with Multiple Clearance Joints[J].Mechanism and Machine Theory,2014,78:105-115.
[6] ZHANG Q H,ZHANG X M,LIANG J L.Dynamic Analysis of Planar 3-RRR Flexible Parallel Robot[C]//Proceedings of IEEE International Conference on Robotics and Biomimetics.IEEE,2012:154-159.
[7] FLORES P.A Parametric Study on the Dynamic Response of Planar Multibody Systems with Multiple Clearance Joints[J].Nonlinear Dynamics,2010,61(4):633-653.
[8] 陈江义,郝雪清,虞启辉.含间隙铰链并联机构的动力学分析[J].郑州大学学报(工学版),2012,33(1):98-101.CHEN J Y,HAO X Q,YU Q H.Dynamic Analysis of Parallel Mechanism with Clearance Revolute Joint[J].Journal of Zhengzhou University(Engineering Science),2012,33(1):98-101.
[9] 盛连超,李威,刘玉飞,等.基于Pro/E和ADAMS的3-RRR并联平台运动学与动力学研究[J].组合机床与自动化加工技术,2015(6):5-7.SHENG L C,LI W,LIU Y F,et al.Research of Kinematics and Dynamics of a 3-RRR Parallel Platform Based on Pro/E and ADAMS[J].Modular Machine Tool & Automatic Manufacturing Technique,2015(6):5-7.
[10] 白争锋.考虑铰间间隙的机构动力学特性研究[D].哈尔滨:哈尔滨工业大学,2011.