This work presents a new architecture of a roundness measuring system in wh
ich the roundness measuring accuracy is not dependent on motion accuracy of
the rotary element. In this architecture, the influence of motion errors o
n roundness measurement is minimized by applying a new error separation tec
hnique developed by Horikawa et. al. [1,2], the improved Reversal Method -
IRM. A prototype that uses: a rotary table supported by ball bearings, non-
contact gap sensors and a computer system that collects and process sensor
readings has been developed. Experimental results have shown that even usin
g a rotary table supported by ball bearings, that has non-repetitive motion
errors larger than 2 mum. the final measurement repeatability is better th
an 0.3 mum of peak-to-peak value. In order to ensure the same levels of acc
uracy of the proposed system, a traditional roundness measuring system desi
gn must use a more precise and therefore more expensive type of bearing wit
h a motion error no larger than 0.1 mum. (C) 2001 Elsevier Science Inc. All
rights reserved.