Accuracy evaluation of squareness identification by vision-based circular tests for machine tools

The accuracy of the identification of machine tool squareness by the vision-based circular test was evaluated. The uncertainty in the squareness identification was evaluated to clarify the accuracy criteria for camera calibration and setup. The simulation and experimental results revealed that the uncertainty owing to the skew factor of the camera was dominant. The conventional calibration performed using a checkerboard plate was insufficient. In contrast, the experimental setup did not require a high accuracy because the alignment error was not significant. The obtained results demonstrated the potential of the vision-based test for an approximate and rapid identification of squareness.