| Summary: | 碩士 === 國立中興大學 === 機械工程學系所 === 107 === The purpose of this study is to discuss the orientation of the rotation axis of any turntable and calibrate it by the line-structured-light measurement system. In the line structure light rotation measurement system, we measure the object Profile in 360° by rotating the turntable, and the rotation axis of the turntable may have eccentric error or skew, which will influence on the measured result. Thus, how to correctly calibrate the orientation of the rotation axis is the focus of the rotation measurement system.
First, we hope to use the standard cylinder as our calibration standard and construct a cylindrical equation which is described in the rotation coordinate system and the measurement coordinate system. We placed a standard cylinder on the turntable, and then we obtained the three-dimensional information about the profile of standard cylinder by the line-structured-light measurement system. In order to improve the accuracy of the measured quality, we must also filter the image and thinning process. After obtaining the three-dimensional coordinates of the standard cylinder, we substitute the coordinate points into the cylindrical equation to fit the cylinder and calculate the relative orientation between the measurement coordinate system and the rotation coordinate system.
In the measurement system, we imagine that the path of projecting the line- structure-light will form a light plane, and the intersection of the light plane and the target is the profile we measured. We project the line-structure-light onto the calibration board to capture the image, and then we obtain the more line-structure-light images under different depth information by moving the correction board at equal intervals.
Since the movement of the calibration board is known, and each line-structure- light image has its corresponding depth information, we can finally calculate the relationship between the light plane and the line-structure-light image. In this paper, the Homography matrix is used to describe the projection relationship between the light plane and the image plane. After measuring the profile image of the object, the depth information can be obtained by using the Homography matrix.
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