Research On Key Techniques Of Line-Structured Light 3-D Measurement System

Laser triangulation is one kind of non-contact 3-D measurement technology, which is widely used in industrial production, quality control and machine vision, etc. Recently, with the rapid development of science and technology, the requirements of laser triangulation in speed and precision become higher and higher. In this paper, a line-structured light 3-D measurement system which bases on the basic principle of laser triangulation is designed, and there are some researches in the key technologies of this system have been done.Firstly, in order to optimize the robustness of the traditional light stripe center extraction algorithm, a new light stripe center extraction algorithm based on the normal direction of the skeleton is proposed, which combined with the actual situation of the line-structured light 3-D measurement system and the characteristics of the light stripe images, and the extraction process and the processing algorithm is designed in details. Finally, this light stripe center extraction algorithm can extract the center accurately even under the complicated situation.Secondly, the mathematical model of the system is built, which is based on the principle of the line-structured light vision sensor and the perspective projection camera transformation model. And the mathematical transformation relational expression between the image coordinate and the world coordinate is deduced in details. And then, in order to simplify the calibration process, reduce the computational complexity and improve the automation degree of the traditional method, a new direct calibration method of line-structured light vision sensor on the basis of linear scale is proposed. Besides, a planar target and an extraction algorithm of feature point is designed. Finally, it could realize the simple, rapid and high accuracy direct calibration of system automatically, by running the automation software and finishing a small amount of manual operation according to the new method.Thirdly, a line-structured light 3-D measurement system is set up as the experiment platform. And the experiments on the light strip center extraction, the system calibration, the measurement precision and 3-D profile measurement have been carried out. The experiment results have verified the effectiveness and practicality of light stripe center extraction algorithm and the calibration method. Besides, the line-structured light 3-D measurement system have play a good comprehensive performance that can meet the basic requirements of industrial production and measurement.