A novel symmetric parallel mechanism 6RPS with multi-redundant actuations is proposed in this paper, which possesses two rotational and one translational degrees-of-freedom. Motion and constraint screw systems of this mechanism are established and then character of the freedom is analyzed. Transmission performance indexes are established, and dimension optimization is operated by considering the distribution of transmission performance. Whole high-performance workspace and performance distribution are analyzed with optimal dimension. Motion interference condition of the mechanism is studied, and accessible posture spaces are analyzed by combining joint space restriction. A comprehensive performance comparison with a counterpart configuration is exhibited. Research results of this paper are of reference significance for both the research of parallel mechanism with two rotational and one translational degrees-of-freedom, and the application of mechanism 6RPS.

This paper focuses on the singularity of actuation coordination of redundantly actuated parallel manipulators and proposes a series of novel indices to evaluate the actuation coordination. The singularity is analyzed based on the coordinated dynamics model and divided into two categories: input singularity and output singularity. Influences of the singularity on the control performance of redundantly actuated parallel manipulators are studied with mechanisms 2RPU + 2UPR + RPR and 3RPR. Local and global performance indices of redundantly actuated parallel manipulators with actuation coordination are put forward, and the dimension optimization method considering the proposed indices is studied based on mechanism 6RPS. The research of this article possesses good reference significance for the performance analysis and control application of redundantly actuated parallel manipulators.