Generalized two-point method for straightness error motion measurement in low spatial frequency domain

摘要

Straightness error motion of a carriage on a machine tool is an important factor for machine accuracy and it is estimated using a hardware datum or virtual self-checking methods. Profile measurement of a large-scale workpiece is in demand in industry. This measurement requires large sampling points. Multi-probe methods generally take difference of sensor's outputs to separate straightness error motion. Since difference works as high-pass filter, the straightness error motion signal is distorted. Then, integration or inverse filtering is used to recover the straightness error motion. Therefore, influence of the sensor's random error tends to be large at low spatial frequency domain. Generalized two-point method can take large sampling number with no pause. This article shows the random error propagation of the generalized two-point method and experimental results with large sampling points.