Complete 3-D Self-calibration of Coordinate Measuring Machines

Self-calibration allows testing machine motion errors without being affected by the precision of calibration artifacts, but its implementation has been limited to 1-D and 2-D domains due to lack of suitable 3-D methodology. We present in this paper an extended algorithm that provides a complete 3-D solution of self-calibration especially for testing coordinate measuring machines. Using a 3-D grid artifact of steel balls, four separate data sets of measurements are taken with different views of the artifact. Then parasitic errors related to the artifact are identified through algebraic manipulation, so that a complete 3-D map of machine systematic errors is constructed. Experimental results validate the proposed algorithm by confirming that the calibration accuracy is limited only by the measurement repeatability of the CMM under test.