Design and experiment of a new translational parallel manipulator with large payload and high repeatability

Parallel manipulators are known to have higher structural rigidity and end-effector speed than serial manipulators. However, the size, payload, rigidity, and repeatability of parallel manipulators highly depend on the types of active and passive joints used. Compared with other joint types, revolute joints are structurally simpler and have an unlimited rotation range. They can be easily preloaded to increase the stiffness and eliminate clearance. Hence, revolute joints are preferable for parallel manipulators that need to have a smaller size, larger payload, and higher reparability. This paper presents a new translational parallel manipulator (TPM) that uses only revolute joints as the active and passive joints. The kinematics, workspace analysis, and singularity analysis are provided to facilitate the design of the new TPM. Finite element analyses are given to evaluate the compliance contribution of the revolute joints and links of the new TPM. Compliance, payload, and repeatability experiments are provided to verify the merits of the proposed design. We expect that the proposed TPM can provide an alternative for selecting parallel manipulators to meet different industrial applications.