Three-translational freedom parallel mechanism with far frame three-lever space

The invention discloses a parallel combined mechanism of three translation degrees of freedom which has three far frame bars, the far frame bars comprise a first far frame side bar, a second far frame side bar and a far frame middle bar which are parallel-arranged, the first far frame side bar and the second far frame side bar are parallel symmetrically arranged on the both sides of the far frame middle bar and the axis is paralleled with the axis of the far frame middle bar; the end terminal of the near frame bar is provided with a pin roll I, the axis of the pin roll I is paralleled with the in the revolving axis of the near frame bar; the moving platform is provided with a pin roll II which is parallel corresponding to the pin roll I, the both ends of the far frame middle bar are connected with the central sections of the pin roll I and the pin roll II through a hook joint, the both end of the far frame side bar are respectively connected with the terminals of the pin roll I and the pin roll II through a ball joint. The parallel combined mechanism of three translation degrees of freedom which has three far frame bars has the advantages that the rigidity is improved by adding the passive constraint of the first far frame side bar, the second far frame side bar on the both sides of the far frame middle bar; the far frame middle bar and the far frame side bar are composed of a mutual gap-emulation structure.