Identification and compensation of geometric parameter errors for Non-Orthogonal shafting laser coordinate measuring instrument

With the deepening research in the field of large-scale coordinate measurement, non-orthogonal shafting 3D laser coordinate measuring instruments provide new possibilities for high-precision measurement in complex scenarios due to their advantages such as compact structure and strong adaptability. However, the lack of a systematic analysis and a unified model of their key geometric parameter errors limits further improvement in measurement accuracy. To address the issues above, a unified error modeling, identification, and compensation framework based on the product-of-exponentials (POE) model and the global differential of the POE mapping is proposed in this paper. First, an efficient kinematic model of the non-orthogonal shafting laser coordinate measuring instrument (N-SLCMI) is established, and the pose error propagation equation between geometric parameter errors and the terminal measuring axis is derived. Furthermore, a geometric parameter error identification model is constructed using coordinate errors as observations, and a complete error compensation strategy is developed. Finally, practical experiments demonstrate that the proposed method converges rapidly and effectively reduces the coordinate measurement errors of the N-SLCMI. For the training set, the average measurement error is reduced from 1.8898 mm to 0.1876 mm, while the RMSE decreases from 2.0908 mm to 0.2394 mm. For the test set, which is not involved in the error identification process, the average measurement error is reduced from 1.7145 mm to 0.2363 mm, and the RMSE decreases from 1.8315 mm to 0.2542 mm. These results demonstrate that the proposed method can effectively improve the coordinate measurement accuracy, providing theoretical foundations and practical guidance for the development and application of high-precision non-orthogonal shafting 3D measurement technology.