Rapid non-contact measurement of distance between two pins of flexspline in harmonic reducers based on standard/actual parts comparison

In order to achieve rapid and precise measurement of distance between two pins of flexspline in harmonic reducers, an rapid non-contact measurement strategy based on standard/actual parts comparison is proposed. Firstly, to eliminate the installation eccentricity error of flexspline fixture, a sine-quadrant eccentricity error elimination method is designed. The sinusoidal curve and quadrant of the measured fixture eccentricity error with respect to the fixture rotation angle is used to calculate the eccentric error components along x and y axes, which has the advantages of simplicity and rapidity. Secondly, a Gaussian-Harmonic Wavelet Filtering (GHWF) algorithm is proposed to filter out the noise in the measurement process, which can effectively suppress the Gibbs phenomenon in harmonic wavelet transformation and improve the signal-to-noise ratio. Finally, an experimental platform including baseplate, turntable, flexspline, moving platform and laser sensor is constructed, in order to verify the performances of error elimination, noise filtering and distance measuring. Experimental results show that the measurement error of the proposed strategy is less than 7 μm, which is consistent with the accuracy obtained by the commercial high-precision gear measuring instrument. The average measurement time is about 29.6 s, much less than the 5 min of the commercial instrument, showing great application potential for the efficient distance measurement of gears and flexsplines.