A Calibration Method Based on Fixed Portal CMM for Digital Leveling Systems

The existing calibration devices for invar barcode leveling staff are complex in structure and require significant space, making such devices rare and limiting related research. To study the metrological performance concerning the comprehensive error of digital leveling systems and the errors of invar barcode leveling staff, a compact calibration device has been developed. This paper introduces the principles and methods of implementing the device, which consists of a fixed portal three-coordinate measuring machine, a planar reflecting mirror, a laser interferometer, and a digital level. Using this device, uncertainty analysis and comparative experiments were conducted to illustrate the differences between the division errors of the barcode leveling staff read directly by the camera and the decoded readings obtained by the digital level. Recommendations are proposed for the calibration of barcode leveling staff and the comprehensive error calibration of digital levelling systems using this apparatus. This is of great significance to support the calibration and traceability studies of related instruments.