Geometric Isotropy Indices For Workspace Analysis Of Spatial Parallel Manipulators

Workspace geometric isotropy analysis is crucial for many applications. It is highly desirable if the workspace of a parallel manipulator is perfectly isotropic. This paper proposes three novel workspace isotropy indices, namely, translational workspace isotropy index, rotational workspace isotropy index, and entire workspace isotropy index, for workspace isotropy analysis of spatial parallel manipulators in terms of the geometric shape of the workspace. All three indices are mathematically defined. The effectiveness of the proposed indices is verified by experiment using random external rotational disturbances. The proposed indices are good indicators of the robustness of a parallel manipulator to external rotational disturbances and can be used as a guideline for optimal design of spatial parallel manipulators.