Title: Singularity analysis of fully-constrained six-DOF cable-driven parallel robots with seven cables
Authors: Xiumin Diao
Addresses: School of Engineering Technology, Purdue University, West Lafayette, Indiana 47907, USA
Abstract: Singularity analysis of parallel robots is an important issue. A parallel robot could be out of control or crash in a singular configuration. The unidirectional constraint of cables makes the singularity analysis of cable-driven parallel robots different from that of rigid-link parallel robots even if they have similar kinematical architectures. This paper discusses various categories of singularities of fully-constrained cable-driven parallel robots. Based on their natures, singularities of cable-driven parallel robots are classified into two categories: the Jacobian singularity and the force-closure singularity. A Jacobian singularity occurs when the Jacobian matrix of a cable-driven parallel robot loses its full rank. When the Jacobian matrix of a cable-driven parallel robot has a full rank, the cables' inability to generate tension will lead to force-closure singularities, which can always happen to fully-constrained cable-driven parallel robots. A method of identifying force-closure singularities of fully-constrained six-DOF cable-driven parallel robots with seven cables is proposed with mathematical proof. Understanding of the natures of singularities is important for the design and control of cable-driven parallel robots.
Keywords: singularity analysis; cable-driven parallel robots; cable robots; singularities; robot design; robot control.
International Journal of Mechatronics and Automation, 2015 Vol.5 No.2/3, pp.133 - 139
Received: 28 Sep 2015
Accepted: 24 Nov 2015
Published online: 18 Apr 2016 *