机构中过约束判定的新方法

A New Determination Method of Overconstraints for Mechanisms

将前期研究中提出的基于杆组参数矩阵的交集规则及过约束判断方法推广到更为一般的过约束机构。从过约束产生的本质出发,讨论了刚性闭合、通过运动链闭合、通过单个运动副闭合,及其过约束,得到了单环路机构中过约束判断的两个准则。对于较复杂机构,借助"结构流程图"的辅助分析,依据闭合方式,通过分析每个闭合过程中对应的杆组参数矩阵来确定过约束。分析了两个典型机构中的过约束,所得结果与实际一致,证明所提方法的方便性和实用性。

A method of overconstraint determination presented by pre-researches based on link group parameter matrix and list intersections, its range of pre-research needed general spatial overconstraint mechanisms. Based on the engendered natures of overconstraints, usual closing forms and corresponding overconstraints were discussed, including rigid closure, closure by kinematic chain,and closure by single joints. Meanwhile,two criteria for judging the overconstraints in a single loop mechanism were obtained. Furthermore,an idea with the aid of ^structural flow dia-gram” to determine the overconstraints for a complex mechanism was put forward. According to theclosing form,the overconstraint might be checked in each closed processes by the corresponding link group parameter matrix. Finally？ two typical mechanisms from the literatures were taken as instances. The results coincide with the prototype data,which shows the convenience and practicality of the pro-posed theory.