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Design and analysis of a totally decoupled 3-DOF spherical parallel manipulator

Published online by Cambridge University Press:  19 November 2010

Dan Zhang*
University of Ontario Institute of Technology, Oshawa, Ontario L1H 7K4, Canada Qingdao Technological University, Qingdao 266033, China
Fan Zhang
Department of Mechanical Engineering, Shanghai University of Engineering Science, Shanghai 201620, China
*Corresponding author. E-mail:


In this paper, we propose a unique, decoupled 3 degree-of-freedom (DOF) parallel wrist. The condition required for synthesizing a fully isotropic parallel mechanism is obtained on the basis of the physical meaning of the row vector in the Jacobian matrix. Specifically, an over-constrained spherical 3-DOF parallel mechanism is presented and the modified structure, which avoids the redundant constraints, is also introduced. The proposed manipulator is capable of decoupled rotational motions around the x, y, and z axes and contains an output angle that is equal to the input angle. As this device is analyzed with the Jacobian matrix, the mechanism is free of singularity within its workspace and maintains homogenous stiffness over the entire workspace.

Copyright © Cambridge University Press 2010

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