Research On Machine-Vision-Aided Three Dimensional Laser Scan Indication

There exists huge demand of indicating three-dimensional target contour curve on freedom curved surface in many industrial applications,such as placement of components,painting logo,composite ply layup and so on.Therefore,a flexible method for laser 3D scan indicating is proposed and a prototype system is built,which utilizes a monocular vision system to assist galvanometric laser scanner to project the target contour curve on the accurate region of the freedom curved surface.The main contents and contributions of this paper are as follows.The overall plan of indicating three dimensional contours on freedom curved surface based on a monocular vision system and a galvanometric laser scanner(GLS)is proposed.Compared to the overseas products,the proposed method do not need the specially-made calibration tools,the procedures of calibration is simpler and easier,and the principle of online calibration guarantees the reliability and accuracy of the indication.It is suitable to realize the laser three dimensional indication of the target contour curve on freedom curved surface.A monocular vision system is built to assist the realization of 3D laser scan indication(3D-LI).The system can easily locate the position and pose of the indication object in its coordinate system,and supply the data for calibrating the system of realizing the 3D laser scan indication.A mapping to realize the 3D laser scan indication is proposed.The mapping represents the relationship between the 3D point that the laser beam hits on the freedom curved surface and the two corresponding control signals of GLS,and the way of the mapping to realize the 3D-LI differs from the mode that must calibrate the structural parameters of GLS.Finally,a neural network model that can describe the mapping is built,and apply Extreme Learning Machine to solve the parameters of the neural network model.So the mapping is calibrated.According to the mapping,the 3D laser scan indication of the target contour curve is realized on freedom curved surface.A prototype system of 3D-LI is constructed,and the results of experiments prove that the 3D-LI system obtains a good indication result.