提出一种新型3支链6自由度机构构型设计方法。对于6自由度并联机构，支链对动平台没有自由度约束，只存在尺度约束。在每条支链中都加入一个球副，用以实现3转动自由度，其余运动副用以实现3移动自由度。以支链中移动副的数目为分类原则，得出了24种通用支链结构，在此基础上，对支链运动副轴线的位置进行特殊配置，得出了对应的新型支链结构。应用得出的支链结构，对其进行组合，设计出一系列6自由度并联机构，并且以简化运动学求解、扩大工作空间为目的，给出支链内部运动副轴线配置及支链空间拓扑位置的配置设计原则。对得出的新型3-RPPS机构进行运动学、尺度约束和工作空间分析，并建立与机构性能相关的尺度要素与构型综合的关系，验证了本方法的有效性。

A novel method is presented to design parallel mechanisms with 3 limbs and 6 degrees of freedom (DOFs) based on limb construction method. For 6-DOF parallel mechanisms, the limb structure only provides dimensional constraint, rather than force or moment constraint. A spherical joint is used to achieve three rotational DOFs. Other limb joints are used to realize the left three translational DOFs. Taken the number of prismatic joints as the classified rule, 24 kinds of general limb structure are proposed. On this basis, the corresponding novel limbs by configuring the joint axes of the limb specially are proposed. Combining the obtained limbs, a class of novel 6-DOF parallel mechanisms is presented. For the purpose of simplifying the kinematics and expanding the workspace of the mechanism, the rules for the configuration of the joints and topological position of the limbs in space are proposed. The kinematics, dimensional constraint and workspace analysis of the proposed novel 3-RPPS parallel mechanism is analyzed. The relationship between structure synthesis and dimensional factors that related to mechanism performance is established.