具有大承载能力的环路解耦两转动并联机构综合方法研究

Research on Synthesis Method of a Loop Decoupling Two-rotation Parallel Mechanism with Large Load Bearing Capacity

为解决解耦机构承载能力弱的问题,提出一种具有大承载能力的环路解耦两转动并联机构型综合方法。基于螺旋理论,提出分支传递力螺旋矩阵与输出运动螺旋矩阵的互易积为对角矩阵(主对角线元素全不为零)的机构解耦判别准则,分析机构输出运动螺旋与传递力螺旋之间的关系,确定出驱动螺旋和非驱动螺旋的形式,将上述运动螺旋进行合理的排序和组合得到基础解耦分支。为使解耦机构更好的应用于工业中,提出冗余驱动分支构造方法,在基础解耦分支中添加冗余驱动分支,构造环路,实现环路内反解同步,构造环路之间彼此解耦的环路驱动分支,既不破坏机构的解耦特性又增加了机构的承载能力,综合出环路解耦两转动并联机构。运动学分析和静力学分析表明,所综合出的机构雅可比矩阵为广义对角阵、同一环路内驱动位移同步,并且承载能力强于传统解耦机构,验证了所提出的综合方法的正确性。通过该方法综合出来的机构,在汽车耐久性测试台架方面具有一定的应用前景。

In order to solve the week load bearing problem of the decoupling parallel mechanism,a new structural synthesis method of two-rotation parallel mechanism with large load bearing capacity is proposed.Based on the screw theory,the parallel mechanism decoupling criterion is proposed that the reciprocal product of the branch transmission wrench screw matrix and the output twist screw matrix is a diagonal matrix(the main diagonal elements are not zero at all),and the relations among the output twist screws and the transmission wrench screws of the mechanism are analyzed.The forms of the driving screw and the non-driving screw are determined,and the above-mentioned twist screws are sorted and combined reasonably to obtain the basic decoupling branch chains.Based on the high load-carrying requirements of the vehicle durability testing platform,the redundant drive branch construction method is proposed.Redundant actuation branches are added to the basic decoupling branch chains to construct loop,realize the synchronization of position inverse solution within the same loop and construct a loop drive branches that are decoupled from each other,which can maintain the decoupling characteristics of the parallel mechanism and increase the load-bearing capacity of the parallel mechanism.The kinematic analysis and static analysis show that the Jacobian matrices the synthesized parallel mechanisms are generalized diagonal matrices and the driving displacement is synchronized in the same loop,and the bearing capacity is stronger than the traditional decoupling mechanism,which verifies the correctness of the proposed structural synthesis method.The mechanism synthesized by this method has a application prospect in automobile durability test bench.