Enumeration and optimum design of a class of translational parallel mechanisms with prismatic and parallelogram joints

Spatial joints (Hooke and spherical joint) generally limit parallel manipulator's motion range and performance, while higher performance will be achieved when applying more planar pairs (prismatic and revolute joint), which can promise small movement constraints and high stiffness. In this paper, a novel design method for three translational degrees of freedom parallel mechanisms containing prismatic joints and parallelogram units ((R-R)₂ linkage) is proposed by mapping relationship with augmented matrices of upper triangular matrix. All these mechanisms can be assembled quickly with modular parts and most of which are partially decoupled. In this study, one of these proposed structures is taken as an example for developing a redundant manipulator. Based on vector-loop equations, its position model is derived and the singular configurations are investigated. Kinematic and static performance of this architecture are conducted, as well as the multi-objective optimization is implemented using Genetic Algorithm.