Abstract：According to geometric definition of the sphericity, a novel evaluation method which named as geometry search approaching method for sphericity error is presented. Firstly, an initial reference point is taken as a datum point and built a regular hexahedron and established an auxiliary points. Secondly, the each auxiliary points and the datum point are used as the centre of the measured sphere to calculate the radius of all measured points. And then modify the side length of the hexahedron or the position of the reference point by comparing these radius extreme differences. Finally, by repeating this process, the minimum zone containing all measurement points is obtained and the minimum zone evaluation for the measured spherical surface is implemented. The method is used to process a group of metrical data, and the results indicate that the sphericity error value from this algorithm can be reduced by 0.6μm as compared with least square method, and are consistent with the results obtained by the analytic method and evolutionary computation method. The results show that the algorithm can get not only the minimum zone solution accurately but also has good stability.
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2016, Vol. 37 
