Enlarging parallel robot workspace through Type-2 singularity crossing. (June 2015)

• Record Type: Journal Article
• Authors: Pagis, Georges; Bouton, Nicolas; Briot, Sebastien; Martinet, Philippe
• Is Part Of: Control engineering practice. Volume 39(2015)
• Page Start: 1
• Page End: 11
• Publication Date: 2015-06
• Subjects: Parallel robots -- Computed torque control -- Multi-model approach -- Singularities; Automatic control -- Periodicals; 629.89
• DOI: 10.1016/j.conengprac.2015.01.009
• Languages: English
• ISSNs: 0967-0661

Abstract

Abstract: In order to increase the reachable workspace of parallel robots, a promising solution consists of the definition of optimal trajectories that ensure the non-degeneracy of the dynamic model in the Type 2 (or parallel) singularity. However, this assumes that the control law can perfectly track the desired trajectory, which is impossible due to modeling errors. This paper proposes a robust multi-model approach allowing parallel robots to cross Type 2 singularities. The main idea is to shift near singularities to a simplified dynamic model that can never degenerate. The two main contributions are the definition of an optimal trajectory crossing Type 2 singularities and the multi-model control law allowing to track this trajectory. The proposed control law is validated experimentally through a Five-bar planar mechanism.