IOP Publishing

The author examines current practice in the multiprobe method of roundness measurements, and derives design strategies for improved measurement accuracy and reliability. The multiprobe method eliminates variable centring errors by combining displacement measurements made simultaneously at several points about the periphery of the workpiece. Discrete signal processing methods for reconstruction of the workpiece profile are described, and design guidelines are established to eliminate the detrimental effects of aliasing from the reconstruction process. The harmonic response of a three-probe arrangement is investigated, and methods are developed to avoid the unwanted suppression of harmonics. The advantages of a more complex multiprobe arrangement are discussed, and a novel harmonic reconstruction method used to avoid suppression, and to allow the detection of incorrect measurements by a redundancy technique.