Evaluating surface roughness of curved surface with circular profile based on arithmetic circular arc fitting

A procedure based on Kasa fit for evaluating the surface roughness of a curved surface with a circular arc profile was suggested in this paper. To investigate the effectiveness of the method, some curved surface profiles with preset surface roughness were numerically generated, and their surface roughness was evaluated by the procedure based on Kasa fit. And the surface roughness of two experimental surface profiles evaluated by the method based on Kasa fit was compared with those evaluated by linear fitting and quadratic polynomial fitting to demonstrate both the effectiveness and the preservation of Kasa fit-based procedure. Results show that the evaluated value of surface roughness by Kasa fit-based procedure only deviated from the actual value by less than 10%, even in the case of considerable fitting parameters' error (>30%). Also, the Kasa fit can report a reasonable value of surface roughness with better preservation of shift and rotation motion of the surface profile compared to both linear fit and quadratic polynomial fitting, especially for the curved surface with a short radius. This procedure based on Kasa fit can be used in evaluating surface roughness of curved surface with circular arc profile no matter what pose of the object under observed.