Abstract: A novel accurate two-probe method in time domain is put forward to measure straight-going component motion error in machine tools. The characteristics of non-periodic and non-closing in straightness profile error are liable to bring about higher order harmonic component distortion in measurement result. However this distortion can be avoided by the new accurate two-probe method in time domain through the algorism of symmetry continuation, uniformity and least square. The harmonic suppression is analyzed in detail through modern control theory. Both straight-going component motion error in machine tools and the profile error in workpiece that is manufactured on this machine can be measured at the same time, all of those information is available to diagnose the fault origin of machine tools. The analysis result is proved to be correct by the experiment.

Key words: Error initial value Motion error, Error separation technology, Tendency profile Symmetry continuation