The application of structured light vision technology to the dimension measurement of mechanical parts can realize the non-contact and accurate in-situ measurement of parts, so that this technology can be widely used in practical industrial measurement. This paper focuses on the calibration technology of structured light vision system and the detection technology of light bar center point, and analyzes the two technologies in detail from the perspective of theory and experiment. On the basis of fully considering the geometric characteristics of involute profile of spur gear, a method of measuring involute profile error by using structured light vision technology is proposed.
- The traditional calibration method of structured light vision system separates the camera calibration and structured light plane calibration into two parts. Considering that the calibration accuracy of the traditional calibration method can not meet the needs of accurate measurement, a calibration method based on all variables of the system is proposed. The experimental analysis shows that a better calibration result can be obtained when the width of the light bar is controlled at about pixels by using a picture of coplanar target. From the calibration residual, it can be seen that the calibration accuracy of the improved calibration method is significantly higher than that of the traditional calibration method.
- According to the geometric characteristics and imaging process of spur gear, a pseudo structured light plane perpendicular to the rotation center line of spur gear is established, and the target point is projected on this plane, which eliminates the measurement error caused by the installation position of structured light vision system. The local coordinate system is established on the pseudo structured light plane, and the three-dimensional coordinates of the projection point are transformed into two-dimensional coordinates on the plane, which reduces the amount of calculation of involute tooth profile error.
- The working principle of semiconductor laser projecting a word line structured light is analyzed, the classical detection method of light strip center point is studied, and the influence factors in the detection model are optimized. Taking the actual size as the unit, the evaluation method of light strip center point detection accuracy based on gauge block is established, and the algorithm with high detection accuracy and good stability is determined as the light strip center point detection method for involute tooth profile error measurement.
- The experiment of measuring the radius of the base circle shows that the method has high accuracy in measuring the radius of the base circle, and the placement position of the structured light vision system will not affect the measurement results; From the measurement experiment of involute tooth profile error, it can be seen that the measurement accuracy of the method can meet the measurement requirements of tooth profile error. The larger the module of spur gear, the higher the measurement accuracy, but the number of spur gear teeth has little effect on the measurement results; Finally, experiments show that the measurement model based on pseudo light plane established in this paper improves the measurement accuracy of involute tooth profile and reduces the requirement of laser projection angle.
The accurate measurement of involute profile error of spur gear is realized by using structured light vision technology, which promotes the development of in-situ measurement technology in NC machining of spur gear.