4SPR+2R type four-freedom-degree parallel mechanism

The invention provides a 4SPR+2R type four-freedom-degree parallel mechanism. A base is composed of four auxiliary rods, four ball pair seats evenly distributed on the circumferential side are arranged on a round plate of the base, a movable platform is composed of two auxiliary rods, parallel through holes are formed in the two opposite sides of a square plate of the movable platform respectively, a first cross shaft and a second cross shaft penetrate through the through holes of the movable platform respectively, through holes are formed in the two ends of the first cross shaft and the two ends of the second cross shaft, and the axes of the two through holes of each cross shaft are parallel and perpendicular to the cross shaft. Four SPR type linear drive branches with the same structure are evenly distributed circumferentially between the movable platform and the base, each SPR type linear drive branch is composed of a rotating pair at the upper end, a movable pair electric cylinder in the middle and a ball pair at the lower end, the ball pairs at the lower ends of the branches are connected with the ball pair seats of the base, the upper ends of two branches are connected with the two ends of the first cross shaft through the rotating pairs, and the upper ends of the other two branches are connected with the two ends of the second cross shaft through the rotating pairs respectively. The 4SPR+2R type four-freedom-degree parallel mechanism has the advantages of being simple in structure, large in work space, high in rigidity, good in translational motion characteristic in all directions and the like.