Kinematics of a Parallel Robot With Six Pairs of Offset Joints

A 6-P-RR-R-RR parallel-kinematics machine (PKM) with axially offset RR-joints is the subject of this article. Different from the universal joint, an axial offset between the two axes of the RR-joint is included. The offset is intended to prevent joint interference, while enlarging the workspace of the whole PKM. Compared with a 6-PUS PKM, the kinematics of the PKM introduced here is significantly more complex due to the axial offsets. The displacement analysis is conducted numerically, and velocity and acceleration analyses are conducted symbolically. The accuracy and effectiveness of the proposed formulation are verified by numerical simulation in adams. In addition, the workspace, singularity, and dexterity analyses of this new type of PKM are conducted and then compared with those of the 6-PUS mechanism.