Three-freedom-degree parallel robot wrists with aligning mechanisms

The invention relates to three-freedom-degree parallel robot wrists with aligning mechanisms. Each three-freedom-degree parallel robot wrist comprises a base, a mobile platform, three movement branched chains with the aligning mechanisms, three spherical pair structures and three power sources, wherein the three movement branched chains with the aligning mechanisms are movably connected with the mobile platform respectively; the three power sources directly drive the movement branched chains to enable the mobile platform to do three-freedom-degree movement; and particularly, as each aligning mechanism is arranged in the middle of each movement branched chain of each robot wrist, the positions of axial lines of three revolute pairs in the middle are adjusted conveniently, and the axial lines of the revolute pairs are enabled to intersect at one point as required, so that processing and assembling errors are reduced, and operation accuracy of each robot wrist is improved. The three-freedom-degree parallel robot wrists are easy in processing and assembling, flexible in movement, compact in structure and good in rigidity, and can be applied to parallel robots, micro-motion robots and other robots.