中文摘要：

为了揭示在外力作用下机构的几何形变对其刚度的影响,掌握其变化规律,为机构参数设计及其刚度控制提供合理参数,对6-PSS空间并联机构的刚度特性进行了系统研究。首先,通过建立约束方程和坐标关联方程,将关节坐标转化为直角坐标,推导出基于守恒协调转换刚度矩阵的6-PSS空间并联机构的刚度映射公式。然后,根据求解结果绘制出不同参数下6-PSS空间并联机构的刚度映射曲线,为对比机构在外力作用下其刚度的改变和研究其变化规律提供参考。最后,根据导出的公式和数值分析算例,对机构的刚度特性进行分析和讨论。

英文摘要：

To reveal the stiffness behavior and find out its change rule in order to provide the reasonable parameters for the structural parameter design and stiffness control, the stiffness characteristics of a 6--PSS spatial mechanism was studied by considering the effects of the change in geometry due to compliance caused by the external forces. First, the joint coordinates were transmitted into Cartesian spaces by forming the constraint equations and the incidence equations, the analytical stiffness equations of the 3--PRR planar parallel mechanism were derived based on the conservative con-gruence transformation （CCT） stiffness matrix. Then, the stiffness maps of the 6--PSS mechanism were plotted with and without external forces in order to show the changes of the stiffness and provide the references for studying its change rules. Finally, the stiffness characteristics of the mechanism were analyzed and discussed according to the stiffness equations and numerical examples.