Parallel mechanism with three freedom degrees of twice rotation and once motion

The invention relates to a parallel mechanism with three freedom degrees of twice rotation and once motion in a robot mechanism. The invention aims at providing the parallel mechanism which has the adThe invention relates to a parallel mechanism with three freedom degrees of twice rotation and once motion in a robot mechanism. The invention aims at providing the parallel mechanism which has the adl lines of first rotating shafts of the two universal hinges in the first branch and the second branch are parallel with each other; central points of the three universal hinges in the three brancaxial lines of first rotating shafts of the two universal hinges in the first branch and the second branch are parallel with each other; central points of the three universal hinges in the three branches are collinear; and the axial line of the first rotating shaft of the universal hinge in the third branch is vertical or parallel to the axial lines of the first rotating shafts of the two universahes are collinear; and the axial line of the first rotating shaft of the universal hinge in the third branch is vertical or parallel to the axial lines of the first rotating shafts of the two universal hinges in the first branch and the second branch.l hinges in the first branch and the second branch.vantages of simple kinematic model, easy control, simple structure, high rapidity and low manufacturing cost. The parallel mechanism with three freedom degrees of twice rotation and once motion is chavantages of simple kinematic model, easy control, simple structure, high rapidity and low manufacturing cost. The parallel mechanism with three freedom degrees of twice rotation and once motion is characterized by comprising a mobile platform, a stand, a first branch, a second branch and a third branch, wherein the first branch, the second branch and the third branch are connected in parallel betwracterized by comprising a mobile platform, a stand, a first branch, a second branch and a third branch, wherein the first branch, the second branch and the third branch are connected in parallel between the mobile platform and the stand; in the three branches, each branch is connected with a first single-freedom-degree motion pair, a second single-freedom-degree motion pair and a universal hingeeen the mobile platform and the stand; in the three branches, each branch is connected with a first single-freedom-degree motion pair, a second single-freedom-degree motion pair and a universal hingein sequence from the stand to the mobile platform, wherein the third branch is additionally provided with a rotating pair between the second single-freedom-degree motion pair and the universal hinge;in sequence from the stand to the mobile platform, wherein the third branch is additionally provided with a rotating pair between the second single-freedom-degree motion pair and the universal hinge;axia