Configuration bifurcation and self-motion analysis of 3SPS + 1PS bionic parallel test platform for hip joint simulator
Configuration bifurcation and self-motion analysis of 3SPS + 1PS bionic parallel test platform for hip joint simulator
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DOI：
10.1016/j.mechmachtheory.2014.12.002
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发表时间：
2015-04
影响因子：
5.2
通讯作者：
G. Cheng;Yang Li;Lanlan Feng;X. Shan;Jianhua Yang
中科院分区：
文献类型：
--
作者：
G. Cheng;Yang Li;Lanlan Feng;X. Shan;Jianhua Yang
提出了一种以3SPS +1 PS空间并联机器人为核心模块的髋关节模拟器。与传统的串行测试平台相比，它在带来更好性能的同时，也克服了其固有的缺陷--单一性。为了分析奇异点附近的机械手的运动行为，整个配置路径对应于单一的输入参数，跟踪的帮助下，前向位置的封闭形式的解决方案。研究揭示了机械臂前向奇异和自由度失控的原因，并通过三维运动仿真进行了验证。然后，提出了一个衡量自由度可控性的位形稳定性指标，并利用其等效运动对自运动进行了定性和定量分析。结果表明：在所有六个分叉点处，非受控自由度都显示出与Z轴相似的方向，与其他两个轴略有偏移。这意味着平台绕Z轴转动不稳定，在该方向上的承载能力较弱。在不同的控制精度下，无控自由度的方向几乎保持不变。该研究为并联机器人实现奇异点处的确定运动、提高运动稳定性提供了分析依据。
A hip joint simulator with a 3SPS + 1PS spatial parallel manipulator as the core module is proposed. Compared to traditional serial test platform, it brings better performance, as also as its inherent defect—singularity. In order to analyze the motion behavior of the manipulator near singular points, the entire configuration paths corresponding to single input parameter, are traced with the help of the closed-form solution of the forward position. The investigation reveals the reason to cause forward singularity and uncontrolled degree-of-freedom (DOF) of the manipulator, and it is verified by 3-D motion simulation. Then, a Configuration Stability Index is proposed to measure the controllability of DOF and a qualitative and quantitative analysis of self-motion is presented using its equivalent motion. The results indicate that: at all six bifurcation points, the uncontrolled DOFs show a similar direction toZ-axis, with slightly offsets to the other two axes. It means that the platform has an unstable rotation aroundZ-axis and a weak load-ability in that direction. Moreover, the direction of uncontrolled DOF almost stays constant under different control precisions. The research provides an analytical basis to achieve the certain motions at singular points and improve the motion stability for parallel manipulator.