## 5 Conclusions  
For the accuracy improvement of the circumferential stitching in the stitching linear-scan method, an attempt has been made to eliminate the data at the edge regions of the arc-profiles in the circumferential stitching process. With a small cylindrical workpiece having a diameter of 3.0 mm, experiments based on the stitching linear-scan method have been carried out. Experimental results have demonstrated that the elimination of the edge part in an arc-profile, where the influence of the pressure angle of the measurement probe in the linear-scan stylus profiler on the measured profile becomes significant, is effective in improving the cross-correlation coefficient of the stitched arc-profiles in the stitching operation. A hardware modification has also been made to the workpiece-holding mechanism in the setup for the stitching linear-scan method. A small round magnet has newly been inserted between the round magnet with the index mark and the workpiece to reduce the influences of the out-of-roundness of the round magnet surface and the side face of the workpiece holder by reducing the contact area between them. Experimental results have demonstrated that the hardware modification is effective in further improving the cross-correlation coefficient in the stitching operation. Experiments have also been extended to evaluate the workpiece having a diameter and a length of 1.5 mm and 5.8 mm, respectively, that cannot have been evaluated by the conventional rotary-scan method. From the whole circumferential profile of the workpiece obtained based on the stitching linear-scan method with improved stitching quality, the diameter and out-of-roundness of the workpiece have successfully been evaluated quantitatively.  
It should be noted that, in this paper, attention has been paid to improving the quality of stitching in the stitching linear-scan method. The comparative tests involving the measurement of roundness deviations of a series of cylinders with the reference method, as well as the harmonic analysis of the profile of a workpiece obtained by the stitching linear-scan method, remain to be addressed, and will be investigated in future work. A comprehensive comparison between the stitching linear-scan method and the conventional rotary-scan method for the clarification of the upper limit of the advantageous workpiece diameter will also be carried out in future work.  
Figure 23: Differences of two neighboring arc-profiles in the overlapped regions obtained by measuring workpieces: (**a**) With a diameter of 3.0 mm; (**b**) With a diameter of 1.5 mm.  
**Author Contributions:** Conceptualization, W.G. and Y.S.; methodology, T.S., Q.L., Y.C., Y.S. and W.G.; software, Q.L. and Y.S.; validation, Y.S., W.G. and H.M.; formal Analysis, Q.L., Y.S. and W.G.; investigation, T.S., Q.L., Y.C. and Y.S.; resources, Y.S. and W.G.; data curation, Y.S. and W.G.; Writing--Original Draft Preparation, Q.L. and Y.S.; Writing--Review and Editing, W.G. and Y.S.; Visualization, W.G. and Y.S.; Supervision, W.G.; Project Administration, W.G.; Funding Acquisition, W.G., Y.S. and H.M. All authors have read and agreed to the published version of the manuscript.  
This work is supported by the Japan Society for the Promotion of Science (JSPS).  
Not applicable.  
The data presented in this study are available on request from the corresponding author.  
The authors would like to thank [PERSON] for his help in the preparation of the experimental setup.  
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript or in the decision to publish the results.