A low-cost 3D dynamic measurement system for CNC machine tool geometric errors based on laser interferometry and dual-ballbar

In view of the existing three-dimensional laser tracking measurement system for detecting machine tool geometric accuracy, the strong dependence on the coordinate system, the difficulty in tracing the measurement results, and the high equipment cost, this study proposes a new low-cost, high-precision three-dimensional hybrid laser-ballbar measurement system and a supporting measurement method. The system comprises a three-dimensional laser dual ballbar and a reference station calibrator. The dual ballbar integrates the high-precision attributes of a laser interferometer with the dynamic measurement capabilities of a conventional ballbar. The base station calibrator is used as a physical reference to evaluate system errors and trace measurement data. The proposed method realizes the measurement and evaluation of three-dimensional dynamic geometric errors and has good versatility. This paper designs and carries out measurement experiments on the positioning error, straightness error and angular error (pitch and yaw) in the X-axis and Y-axis directions and compares and analyzes them with the measurement results of the laser interferometer. The experimental findings indicate that, over a 300 mm measurement range, the X-axis exhibits a maximum positioning deviation of 1.8 μm, with repeatability exceeding 1.51 μm and an expanded uncertainty between 2.82 and 3.98 μm (k = 2). The straightness deviation remains under 2.9 μm, while the peak angular error is 3.6 μrad. For the Y-axis, the maximum positioning deviation reaches 2.3 μm, repeatability is better than 1.5 μm, and the expanded uncertainty lies between 3.14 and 3.88 μm (k = 2). The straightness deviation does not exceed 3.7 μm, and the angular error peaks at 4.6 μrad. These outcomes validate the precision and reliability of the developed measurement system in assessing geometric errors of machine tools, highlighting its promising applicability in engineering contexts.