Machining centers are the highest-valued and most widely used production tools in Japan. Accuracy inspections of machining centers are performed following ISO standards. One of the basic acceptance tests is to verify the positioning accuracy of the linear axes. The positioning accuracy of a single linear or rotary axis can be easily corrected by a numerical control device if the error is known. The error motion of a single linear axis has six degrees of freedom, including the positioning motion. Recently, a laser interferometer that can measure the 6-DOF error motion simultaneously has been developed. This study proposes a method for measuring the positioning accuracy in three dimensions for daily inspection to quickly identify changes in the positioning accuracy. The effectiveness of the proposed method was investigated by image matching of speckle patterns.

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