T2R1-type parallel manipulators with bifurcated planar-spatial motion

This paper presents a new family of T2R1-type parallel manipulators with bifurcated planar-spatial motion of the moving platform. In each branch, the moving platform has two independent translations (T) and one rotation (R) driven by three actuators mounted on the fixed base or on a moving link. The rotation axis is perpendicular to the plane of translations or parallel to this plane. In the first case, the moving platform has a planar motion, and in the second case, a spatial motion. The bifurcation between planar and spatial motion occurs in a constraint singularity in which the connectivity between the moving and fixed platforms increases instantaneously with no change in limb connectivity. Overconstrained/isostatic parallel manipulators with decoupled/uncoupled motions and maximally regular solutions with bifurcated planar-spatial motion of the moving platform are presented for the first time.