Effects of Orientation Angles on the Singularity-Free Workspace and Orientation Optimization of the Gough-Stewart Platform

The singularity-free workspace of parallel mechanisms is highly desirable in a context of robot design. This work focuses on analyzing the effects of the orientation angles on the singularity-free workspace of the Gough-Stewart platform in order to determine the optimal orientation. In any orientation with phi=theta=0 deg and psi not equal +/- 90 deg, the singularity surface becomes a plane coinciding with the base plane. Hence, an analytic algorithm is presented in this work to determine the singularity-free workspace. The results show that the singularity-free workspace in some orientations can be larger than that in the reference orientation with phi=theta=psi=0 deg. However, the global optimal orientation is difficult to determine. Only an approximate optimal orientation is available. The results obtained can be applied to the design or parameter setup of the Gough-Stewart platform. [DOI: 10.1115/1.4000518]