含有恰约束分支的无耦合两转动并联机构型综合

Type Synthesis of Uncoupled Two-rotational Parallel Mechanism with One Pure Constraint Branch

为提高解耦并联机构的刚度和承载能力,基于分支驱动力螺旋理论提出一种含有恰约束分支的无耦合两转动并联机构型综合系统方法。分析了无耦合两转动并联机构的运动解耦性与分支驱动力之间的关系,确定了分支驱动力螺旋的作用形式;研究了机构输入输出运动之间的映射关系,根据机构雅可比矩阵为对角阵的特点,确定了主动分支的驱动力螺旋和主动运动螺旋的具体形式,给出了非主动运动螺旋的确定方法,完成了主动分支的构型综合。最后实现了含有恰约束分支无耦合两转动并联机构的型综合,得到多种新机型。

In order to improve stiffness and loading capability of decoupled parallel mechanisms,a systemic method of type synthesis for the uncoupled two-rotational parallel mechanism with one pure constraint branch was proposed based on branch actuation wrench screw theory.The relationship between motion decoupling and branch actuation wrench of the uncoupled two-rotational parallel mechanism was analyzed,and the action forms of the branch actuation wrench screws were determined.Mapping relationship between input and output motions of the parallel mechanism was studied.According to the characteristic of Jacobian matrix which was a diagonal one,real forms of the actuation wrench screws and actuated twist screws of driving branches were derived.The law determining the non-actuated twist screws was established.As a result,structural synthesis of the driving branches was completed.Finally,type synthesis of the uncoupled two-rotational parallel mechanism with one pure constraint branches was realized and some new parallel mechanisms were obtained.