Kinematics and workspace analysis of a 3-CR(Pa)(Pa)R parallel mechanism with an orthogonal layout.

The authors report on the kinematics and workspace analysis of a six-dof 3- C R(Pa)(Pa)R parallel mechanism (PM) with an orthogonal layout, which is found to bear various advantageous features. A compact forward-kinematics model is established, leading to a linear univariate characteristic polynomial, significantly reducing the computational cost. Moreover, the velocity-level kinematics indicates that the rotation and translation of the moving platform (MP) are decoupled, and the mechanism under study can achieve isotropy upon proper dimensioning; furthermore, the forward and inverse singularities are found to be solely dependent on the MP orientation, which can be characterized by six elliptical arcs in the orientation workspace; the study also reveals that the MP can theoretically rotate about any axis for at least ± 90 ° before encountering these singularities. Finally, its interference-free workspace is evaluated, indicating that the mechanism under study can offer a relatively large orientation workspace. The foregoing features make the proposed PM potentially attractive in a wide range of applications. • A 3- C R(Pa)(Pa)R PM with an "orthogonal layout" is studied in-depth. • A forward-kinematics model yielding a linear characteristic polynomial is established. • The robot bears decoupled motion, which can become isotropic with proper dimensions. • Six elliptical arcs fully characterize its forward and inverse singularities. • It offers a relatively large interference-free orientation workspace. [ABSTRACT FROM AUTHOR]