各向同性3R空间并联机构的型综合

Structural Synthesis of Isotropic Parallel Mechanism with Three-Rotation Degrees of Freedom

基于螺旋理论提出动平台分别绕x、y、z转动时,具有各向同性的三转动并联机构型综合的方法。基于各向同性机构速度雅克比矩阵为对角阵,且对角线上各元素值相等的条件,给出各分支主动副的类型;根据驱动力螺旋与同一分支中的非主动螺旋互易积为零的条件,求出各分支中非主动副的类型及配置;依据三维转动GF集理论的求交法则从综合出来的分支中选择3条分支进行机构型综合。综合得到的三转动并联机构具有完全各向同性,所以控制简单且具有良好的运动学性能和力传递性能。

This paper presents the structural synthesis of isotropic three - rotational （ 3 R ） parallel mechanism based on theory ofscrew on the condition that the moving platform rotates around the x 、y 、z axis respectively. The type of active joint of each limb is obtainedon the basis of the condition that velocity Jacobian matrix of the isotropic mechanism is diagonal matrix and the value of eachelement on the diagonal line is equivalent .The forms and configuration of the inactive joints are determined according to the characteristicsthat the reciprocal products of the actuated screws and inactive screws in the identical limb are equal to zero. The three limbsare selected from synthesized limbs in accordance with intersection algorithm of GF of three-rotational to do the structural synthesis.The mechanism synthesized can be well controlled and is of the perfect performance in kinematics and force transmission because ofits fully-isotropic.