构型设计是机器人创新设计的重要阶段，考虑机构特性建立逻辑运算法则、从运动合成角度建立并联机器人构型设计方法，比较符合基于逻辑推理和形象思维、从无到有根据设计任务构造方案的设计需要。鉴于并联机器人的支链结构决定了末端转动特征的迁移能力，提出支链末端特征的实轴迁移定理和虚轴迁移定理。实轴迁移定理指支链末端的转动特征决定于支链中转动铰链的轴线位置，该转动特征沿移动特征方向具有迁移能力；虚轴迁移定理指支链末端的转动特征在与之垂直的末端移动特征平面上具有平行迁移能力，分6种不同情况采用虚设转动副法分别利用自由度分析加以证明。利用轴线迁移定理分析了两种新机构的末端转动特征。

Type synthesis is an important stage of innovative robot design. It corresponds with the design requirements from scratch according to design tasks using logical reasoning and imaginary thinking to establish logical operation principles considering mechanism characteristics and construct a type design method of parallel robots from the view point of motion combination. Considering that the limb configuration determines the movement capability of rotation characteristics of the distal link in the parallel mechanisms, the real axis movement theorem and virtual axis movement theorem are proposed. The real axis movement theorem refers to that the rotation characteristics of the limb distal link is determined by the position of one revolute joint in the limb and has movement capability along the direction of some translation characteristics of the revolute joint, while the virtual axis movement theorem means that the rotation characteristics of the limb distal link has movement capability along the plane perpendicular to the rotation axis spanned by any two translation characteristics directions. The virtual axis movement theorem is proofed in all six cases by mobility analysis of the virtual closed-loop linkage formed by adding a fixed revolute joint at distal link. Two novel parallel mechanisms are analyzed by applying the proposed theorems.