Structural Synthesis and Classification of the 4DOF(3T-1R)Parallel Robot Mechanisms Based on the Units of Single-Opened-Chain

Based on the units of single-opened-chain limb, some structural laws of degenerate-rank parallel robot mechanisms are revealed, and a systematic and effective new method for structural synthesis of 4d.o.f. (3T-1R) parallel robot mechanisms is put forward in this paper. 50 new mechanisms are synthesized and classified. The method proposed in this paper is of universal significance and has been used for the structural synthesis of degenerate-rank parallel robot mechanisms with other kinematics output types.