Kinematics of the translational 3-URC mechanism

The use of less than six degrees of freedom (dof) mechanisms instead of six-dof ones is always recommended when the application makes it possible, since their architectures and control are simpler to manufacture and implement respectively. Three-dof mechanisms constitute an important subset of less-than-six-dof mechanisms, since either translational or spherical motion can be obtained through three-dof spatial mechanisms and many industrial applications require the only translational or spherical motion. This paper presents a new translational parallel mechanism (TPM), named translational 3-URC. The new mechanism belongs to the parallel architectures with 3-URC topology, which contain another architecture that is a spherical parallel wrist. The proposed TPM is not overconstrained and has three equal legs whose kinematic pairs are three revolute pairs and one passive cylindrical pair per leg. Its actuated pairs are three revolute pair located on the frame. The position and velocity analyses of the translational 3-URC will be addressed and solved. Its singularity conditions will be written in explicit form and geometrically interpreted.

[1]  R. Clavel,et al.  A Fast Robot with Parallel Geometry , 1988 .

[2]  J. M. Hervé,et al.  Structural synthesis of 'parallel' robots generating spatial translation , 1991, Fifth International Conference on Advanced Robotics 'Robots in Unstructured Environments.

[3]  Raffaele Di Gregorio,et al.  Kinematics of a new spherical parallel manipulator with three equal legs: The 3-URC wrist , 2001, J. Field Robotics.

[4]  Lung-Wen Tsai,et al.  Kinematics of A Three-Dof Platform with Three Extensible Limbs , 1996 .

[5]  M. Karouia,et al.  A Three-dof Tripod for Generating Spherical Rotation , 2000 .

[6]  Vincenzo Parenti-Castelli,et al.  A Translational 3-dof Parallel Manipulator , 1998 .

[7]  Raffaele Di Gregorio,et al.  A new parallel wrist using only revolute pairs: the 3-RUU wrist , 2001, Robotica.

[8]  Rezia Molfino,et al.  A cost-effective purely translational parallel robot for rapid assembly tasks , 2002 .

[9]  Sunil K. Agrawal,et al.  Fabrication and Analysis of a Novel 3 DOF Parallel Wrist Mechanism , 1995 .

[10]  M. Husty.  An algorithm for solving the direct kinematics of general Stewart-Gough platforms , 1996 .

[11]  Vincenzo Parenti-Castelli,et al.  Echelon form solution of direct kinematics for the general fully-parallel spherical wrist , 1993 .

[12]  Gregory Walsh,et al.  Kinematics of a novel three DOF translational platform , 1996, Proceedings of IEEE International Conference on Robotics and Automation.

[13]  Damien Chablat,et al.  Architecture optimization of a 3-DOF translational parallel mechanism for machining applications, the orthoglide , 2003, IEEE Trans. Robotics Autom..

[14]  Xin-Jun Liu,et al.  A three translational DoFs parallel cube-manipulator , 2003, Robotica.

[15]  C. Gosselin,et al.  The optimum kinematic design of a spherical three-degree-of-freedom parallel manipulator , 1988 .

[16]  Marco Carricato,et al.  Singularity-Free Fully-Isotropic Translational Parallel Mechanisms , 2002, Int. J. Robotics Res..

[17]  Gregory Walsh,et al.  Optimization of a three DOF translational platform for well-conditioned workspace , 1997, Proceedings of International Conference on Robotics and Automation.