Nguyen Quoc Khanh, Kim Seungman, Han Seong-Heum, Ro Seung-Kook, Kim Seung-Woo, Kim Young-Jin, Kim Wooram, Oh Jeong Seok
Department of Ultra-Precision Machines and Systems, Korea Institute of Machinery and Materials, Daejeon 34103, Korea.
Department of Nano-Mechatronics, University of Science and Technology, Daejeon 34113, Korea.
Sensors (Basel). 2020 Dec 18;20(24):7288. doi: 10.3390/s20247288.
Multilateration tracking systems (MLTSs) are used in industrial three-dimensional (3D) coordinate measuring applications. For high-precision measurement, system parameters must be calibrated properly in advance. For an MLTS using absolute distance measurement (ADM), the conventional self-calibration method significantly reduces estimation efficiency because all system parameters are estimated simultaneously using a complicated residual function. This paper presents a novel self-calibration method that optimizes ADM to reduce the number of system parameters via highly precise and separate estimations of dead paths. Therefore, the residual function to estimate the tracking station locations can be simplified. By applying a suitable mathematical procedure and solving the initial guess problem without the aid of an external device, estimation accuracy of the system parameters is significantly improved. In three self-calibration experiments, with ADM repeatability of approximately 3.4 µm, the maximum deviation of the system parameters estimated by the proposed self-calibration method was 68.6 µm, while the maximum deviation estimated by the conventional self-calibration method was 711.9 µm. Validation of 3D coordinate measurements in a 1000 mm × 1000 mm × 1000 mm volume showed good agreement between the proposed ADM-based MLTS and a commercial laser tracker, where the maximum difference based on the standard deviation was 17.7 µm. Conversely, the maximum difference was 98.8 µm using the conventional self-calibration method. These results confirmed the efficiency and feasibility of the proposed self-calibration method.
多边测量跟踪系统（MLTSs）用于工业三维（3D）坐标测量应用。对于高精度测量，必须提前正确校准系统参数。对于使用绝对距离测量（ADM）的MLTS，传统的自校准方法显著降低了估计效率，因为所有系统参数都是使用复杂的残差函数同时进行估计的。本文提出了一种新颖的自校准方法，该方法通过对死路径进行高精度和单独估计来优化ADM，以减少系统参数的数量。因此，可以简化用于估计跟踪站位置的残差函数。通过应用合适的数学程序并在无需外部设备帮助的情况下解决初始猜测问题，系统参数的估计精度得到了显著提高。在三个自校准实验中，ADM的重复性约为3.4 µm，所提出的自校准方法估计的系统参数的最大偏差为68.6 µm，而传统自校准方法估计的最大偏差为711.9 µm。在1000 mm×1000 mm×1000 mm体积内进行的3D坐标测量验证表明，所提出的基于ADM的MLTS与商用激光跟踪仪之间具有良好的一致性，基于标准偏差的最大差异为17.7 µm。相反，使用传统自校准方法时最大差异为98.8 µm。这些结果证实了所提出的自校准方法的有效性和可行性。
