Abstract:To study the dynamic coupling between the active branches of parallel manipulator in joint space, a dynamic model of general parallel manipulator in joint space is established firstly, and a dynamic coupling strength coefficient is defined based on the analysis of dynamic coupling moment. The coefficient with a unified scale is suitable for describing the dynamic coupling characteristics of general parallel manipulators. Secondly, the dynamic coupling strength coefficient is applied to analyzing the dynamic coupling characteristics of a 2(3HUS+S) parallel manipulator, and the variation law of dynamic coupling characteristics along the desired motion trajectory is obtained. The actual dynamic coupling moments of the active branches are measured in experiments, which verify the effectiveness of the theoretical studies. Finally, variation of the dynamic coupling strength coefficient along with the structural parameters is calculated for the 2(3HUS+S) parallel manipulator. In order to reduce the dynamic coupling between the active branches, the length of the joint lever and the ratio of the radius of the moving platform to the radius of the base platform should be reduced properly.
[1] Li B, Li Y M, Zhao X H. Kinematics analysis of a novel over-constrained three degree-of-freedom spatial parallel manipulator[J]. Mechanism and Machine Theory, 2016, 104:222-233.
[2] 陈宇航,赵铁石,宋晓鑫,等.变结构并联多维振动台自由度特性与运动学分析[J].机器人,2016,38(2):135-143.Chen Y H, Zhao T S, Song X X, et al. Analysis of DOF properties and kinematics for variable configuration parallel multi-dimensional vibration platform[J]. Robot, 2016, 38(2):135-143.
[3] 王冬,吴军,王立平,等.3-PRS并联机器人惯量耦合特性研究[J].力学学报,2016,48(4):804-812.Wang D, Wu J, Wang L P, et al. Research on the inertia coupling property of a 3-PRS parallel robot[J]. Chinese Journal of Theoretical and Applied Mechanics, 2016, 48(4):804-812.
[4] Chu X B, Gao F. Kinematic coupling complexity of heavy-payload forging manipulator[J]. Robotica, 2012, 30(4):551-558.
[5] Liu X, Zhao T S, Luo E J, et al. Coupling 3-PSR/PSU 5-axis compensation mechanism for stabilized platform and its analysis[J]. Proceedings of the Institution of Mechanical Engineers, Part C:Journal of Mechanical Engineering Science, 2013, 227(7):1619-1629.
[6] Zhang X P, Mills J K, Cleghorn W L. Coupling characteristics of rigid body motion and elastic deformation of a 3-PRR parallel manipulator with flexible links[J]. Multibody System Dyna-mics, 2009, 21(2):167-192.
[7] Gao G Q, Wen J, Liu X J, et al. Synchronous smooth sliding mode control for parallel mechanism based on coupling analysis[J]. International Journal of Advanced Robotic Systems, 2013, 10:No.173.
[8] Shao Z F, Tang X Q, Chen X, et al. Research on the inertia matching of the Stewart parallel manipulator[J]. Robotics and Computer-Integrated Manufacturing, 2012, 28(6):649-659.
[9] Afzali-Far B, Andersson A, Nilsson K, et al. Influence of strut inertia on the vibrations in initially symmetric Gough-Stewart platforms-An analytical study[J]. Journal of Sound and Vibration, 2015, 352:142-157.
[10] Liu Z H, Tang X Q, Shao Z F, et al. Dimensional optimization of the Stewart platform based on inertia decoupling characteristic[J]. Robotica, 2016, 34(5):1151-1167.
[11] Yang C F, Qu Z Y, Han J W. Decoupled-space control and experimental evaluation of spatial electrohydraulic robotic manipulators using singular value decomposition algorithms[J]. IEEE Transactions on Industrial Electronics, 2014, 61(7):3427-3438.
[12] 何景峰,叶正茂,姜洪洲,等.基于关节空间模型的并联机器人耦合性分析[J].机械工程学报,2006,42(6):161-165.He J F, Ye Z M, Jiang H Z, et al. Coupling analysis based on joint-space model of parallel robot[J]. Journal of Mechanical Engineering, 2006, 42(6):161-165.
[13] Shan X L, Cheng G, Liu X Z. Note:Application of a novel 2(3HUS+S) parallel manipulator for simulation of hip joint motion[J]. Review of Science Instruments, 2016, 87(7):No. 076101.