Free-leg Hexapod: A novel approach of using parallel kinematic platforms for developing miniature machine tools for special purpose operations

The paper reports on the development, calibration and exploitation of a novel configuration of parallel kinematic platform, Free-leg Hexapod (FreeHex), on which the base (fixed) platform has been removed; thus, each leg can be individually positioned on workpiece surfaces of non-flat geometries. To enable the utilisation of FreeHex as a miniature machine tool, calibration methods (to reference the platform against the workpiece), work volume calculations, and collision assessment procedures have been developed. The concept of this novel miniature machine tool was demonstrated by generating standard test pieces as well as freeform surfaces followed by accuracy assessments.