Kinematics and Singularity Analysis of a Parallel Manipulator with Three Rotational and One Translational DOFs

• Autores: Soheil Zarkandi
• Localización: Mechanics based design of structures and machines, ISSN 1539-7734, Vol. 39, Nº. 3, 2011, págs. 392-407
• Idioma: inglés
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• Resumen

  • This paper addresses kinematics and singularity analysis of a novel symmetrical four degrees of freedom (DOFs) parallel manipulator, known as 4UPS +1PS manipulator. The manipulator consists of two rigid bodies, one movable (platform) and the other fixed (base), connected to each other by five serial chains (legs), four UPS-type active legs, and one PS-type passive leg where P, U, and S stand for prismatic, universal, and spherical joints, respectively. First, the inverse and direct position kinematics of the manipulator are investigated. The direct position kinematics leads to an even twelfth-degree polynomial in a single variable indicating that the manipulator has two sets of at most six assembly configurations which are symmetric with respect to each other. Through a numerical example it is shown that the polynomial is minimal. Then, the inverse and direct velocity kinematics problems are solved and singularity of the manipulator is analyzed using Jacobian matrices. Also the number and type of additional uncontrollable DOF(s), obtained in direct kinematics singularities, are identified using screw theory.