Study On Field Calibration Method For Line Structured Light Vision Sensor

The dissertation is drawn up during the work of the project 2004BS05002 which is supported by doctoral fund of Shandong province. Aiming to solve some key problems in the filed calibration for line structured light vision sensor, the author made comprehensive studies on them both theoretically and in practice. After all some important theories and methods of field calibration for line structured light vision sensor are creatively presented, and proved by computer software program and experiments.The main and creative work in the dissertation includes the following aspects:1. The mathematical model of the CCD camera is established based on the basic structure and principle of camera, and the appropriate project of error compensation is presented based on the inborn elements. The project predigests the mathematical model of the camera and can meet the requirements of project measure.2. Aiming at the requirements of field calibration, a planar gridding target is designed instead of the three-dimensional target due to the high cost and low accuracy of three-dimensional target. It is guaranteed that the field calibration is simple, convenient and practical. In addition, the planar gridding target is improved based on the inborn elements of errors, the error of image processing is avoided. The radial-alignment-constraint method is proposed based on the analysis of calibration methods for CCD camera.3. The actual accuracy of an optical measurement system is due to the calibration accuracy. The calibration methods should possess the property of convenience and dependability. Current, many calibration methods are used, but only in laboratory. Since the implement of these calibration methods is complicated, they are not suitable for frequent and fast calibration.For solving this problem, a novel calibration method to determine all the intrinsic parameters of the line structured light vision sensor with planar gridding target is proposed. The calibration target can be located randomly at several positions , all the parameters can be readily calibrated on site with the calibrated feature points lying on more than 2 local world coordinate frames respectively. The global world coordinates of the calibration feature points in the local world coordinate frame can be computed through the three dimensional camera coordinate frames.The proposed approach greatly reduces the cost of the calibration equipment and simplifies the calibrating procedure,so it can promote the engineering applications of the line structured light vision sensor handily. Experiments indicate that this method is simple, convenient and practical with high accuracy.