Zhao Xiaowei, Du Huifu, Yu Daguo
School of Mechanical Engineering, North University of China, Taiyuan 030051, China.
Shanxi Deep Hole Processing Engineering Technology Research Center, Taiyuan 030051, China.
Sensors (Basel). 2024 May 16;24(10):3158. doi: 10.3390/s24103158.
Deep hole measurement is a crucial step in both deep hole machining and deep hole maintenance. Single-camera vision presents promising prospects in deep hole measurement due to its simple structure and low-cost advantages. However, the measurement error caused by the heating of the imaging sensor makes it difficult to achieve the ideal measurement accuracy. To compensate for measurement errors induced by imaging sensor heating, this study proposes an error compensation method for laser and vision-based deep hole measurement instruments. This method predicts the pixel displacement of the entire field of view using the pixel displacement of fixed targets within the camera's field of view and compensates for measurement errors through a perspective transformation. Theoretical analysis indicates that the perspective projection matrix changes due to the heating of the imaging sensor, which causes the thermally induced measurement error of the camera. By analyzing the displacement of the fixed target point, it is possible to monitor changes in the perspective projection matrix and thus compensate for camera measurement errors. In compensation experiments, using target displacement effectively predicts pixel drift in the pixel coordinate system. After compensation, the pixel error was suppressed from 1.99 pixels to 0.393 pixels. Repetitive measurement tests of the deep hole measurement instrument validate the practicality and reliability of compensating for thermal-induced errors using perspective transformation.
深孔测量是深孔加工和深孔维护中的关键步骤。单目视觉由于其结构简单和成本低的优点，在深孔测量中展现出广阔的前景。然而，成像传感器发热引起的测量误差使得难以达到理想的测量精度。为了补偿成像传感器发热引起的测量误差，本研究提出了一种基于激光和视觉的深孔测量仪器的误差补偿方法。该方法利用相机视场内固定目标的像素位移来预测整个视场的像素位移，并通过透视变换来补偿测量误差。理论分析表明，透视投影矩阵会因成像传感器发热而发生变化，这会导致相机的热致测量误差。通过分析固定目标点的位移，可以监测透视投影矩阵的变化，从而补偿相机测量误差。在补偿实验中，利用目标位移有效地预测了像素坐标系中的像素漂移。补偿后，像素误差从1.99像素抑制到0.393像素。深孔测量仪器的重复性测量测试验证了使用透视变换补偿热致误差的实用性和可靠性。
