分析在特殊杆长条件下一种运动限定机构的运动特性。在不同的构型下，运动限定机构可以分别执行一个转动加一个平移运动、一个平移运动、一个转动运动。将运动限定机构与具有两个转动和两个移动运动的串联支链相结合，设计出一类具有可重构特性的混联支链。基于李群理论，得到了混联支链在不同构型下运动的群论表达式。利用三条同样的混联支链连接动平台和定平台，得到了一类新型可重构并联机构。当所有混联支链中的运动限定机构处于奇异位置时，可重构并联机构具有瞬时的6自由度。通过控制运动限定机构运行至不同的构型，可重构并联机构能切换至不同的自由度模式，可以执行四种不同特性的3自由度运动。

The motion characteristic of a discontinuously movable mechanism with special link length condition is analyzed. In different configurations, the discontinuously movable mechanism has one rotational and one translational motions, one translational motion, one rotational motion, respectively. Reconfigurable hybrid limbs are obtained by integrating the discontinuously movable mechanism with serial limbs that have two rotational and two translational motions. The kinematic bonds associated with the hybrid limbs in different configurations are identified based on Lie group theory. A class of reconfigurable parallel mechanisms is constructed with three identical hybrid limbs connecting the moving platform and the fixed base. When all the discontinuously movable mechanisms in the hybrid limbs are in singular position, the reconfigurable parallel mechanisms have instantaneous six degrees of freedom. By actuating the discontinuously movable mechanisms move into different motion branches, the reconfigurable parallel mechanisms have the ability to perform different kinds of motion, including four kinds of motion with three degrees of freedom.