少自由度变胞并联机构综合设计方法

摘要

为实现可重组并联机构的创新设计,提出基于基本支链构型的变胞并联机构设计方法.该方法从少自由度并联机构动平台所受的约束出发,运用螺旋理论中相逆螺旋的性质,构造约束螺旋为力或力偶的两类基本支链,并根据基本支链构型的特点构造变胞支链,实现并联机构的变胞设计.对构型相似的线矢力和力偶基本支链进行融合得到变胞支链,通过锁住不同运动副的方式实现变胞支链在两类基本支链之间转化,构造出动平台约束性质可变的变胞并联机构;根据基本支链约束螺旋的方向特点,通过改变运动副轴线方向的方式实现支链约束螺旋方向的改变,进而构造出动平台约束方向可变的变胞并联机构.用所提出的变胞并联机构设计方法,结合Bricard机构的单自由度运动特性,实现动平台为Bricard机构的变胞并联机构的构造.基于基本支链构型进行变胞并联机构构型设计,根据动平台的约束对变胞支链进行组合和变型,实现变胞并联机构的综合,为机构创新设计奠定基础.%To realize the innovative design of reconfigurable parallel mechanism, a design method of metamorphic parallel mechanism based on basic subchain configurations is proposed. Starting from the constraints acting on the moving platform of lower-mobility parallel mechanism, the basic subchains whose constraint is a force or a couple using characteristics of reciprocal screw are constructed. And according to configuration characteristics of the basic subchains, metamorphic subchains are constructed to realize the design of metamorphic parallel mechanism. The line vector force and couple subchains whose configurations are similar are combined to construct metamorphic subchains. The metamorphic subchains can transform between two types of basic subchains by locking different kinematic pairs, then the parallel mechanisms whose constrained type is variable can be constructed. According to the constrained screw direction characteristics of basic subchains, the force direction of subchain is changed by changing the axis direction of kinematic pairs, then the parallel mechanism whose constrained force direction is variable can be constructed. At the same time, using the proposed metamorphic parallel mechanism design method and Bricard linkage' s single degree of freedom motion, a new type of parallel mechanism whose moving platform is Bricard linkage is constructed. Based on the basic subchains, the configurations of the metamorphic parallel mechanism are constructed. According to the constraint of the moving platform, the metamorphic subchains are combined and transformed, which realizes the type synthesis of metamorphic parallel mechanism and lays the foundation for innovation design of mechanism.