中文摘要：

为了利用已知机构形式拓宽建筑可变结构的设计思路,平行四边形环链机构被作为一类结构式机构进行几何构造形式的分析与衍化拓展.对2类平行四边形环链机构即旋板机构与双链形连杆机构从杆件几何连接形式上作对比分析,结果表明每一种旋板机构都可以对应一种双链形连杆机构,结果指出双链形连杆机构亦可设计成绕定点转动开启的板式结构;用欧氏几何分析方法解析平行四边形开链的运动机理,推得平行四边形环链机构共有的运动特性与可动条件;分析You和Wohlhart机构拓展思路所存在的问题,提出广义可折叠杆系结构（FBS）径向拓展和环向拓展2种拓展方法.

英文摘要：

Since the design of movable structures can be inspired by taking full advantage of existent basic mechanisms, parallelogram closed-loop linkages suitable as structural mechanisms were presented and the alternative forms were discussed. Swivel-chain linkages and double-chain linkages are actually two different forms of parallelogram closed-loop linkages. Starting with comparing geometric elements of the two forms, a correspondence is found that every swivel-chain linkage can evolve a double-chain linkage. The result shows that the double-chain linkage can be also designed into retractable plate structure containing fixed external supports. Then the motion principle of open chain was derived by using Euclid geometry method. Based on the derivation, the motion characteristic and the mobility condition of closed chain were verified. On the basis of review and analysis of You and Wohlhart＇s explorations for radial extending, two new methods called general （foldable bar structures, FBS） radial extending and circular extending were proposed.