Study On 3D Laser Scanning System Based On Industrial Robot

Three-dimensional shape measurement technology is widely used in modern industrial manufacturing, and also it is one of research focuses in industrial measurement field. In this thesis, a flexible vision shape measurement system for industrial manufacturing is proposed, which is composed of a line-structured-light sensor and an industrial robot. This system can realize flexible, versatile, automatic and non-contact measurement. The structure of the system is introduced in detail, and several key techniques are studied, including the calibration of robot hand-eye, calibration of the robot itself, point cloud processing algorithms, and so on.The main research work is as follows:1. The current space coordinate measurement technologies are summarized. Combining the advantages of vision sensor and robot, a flexible vision shape measurement system based on industrial robot is put forward. The structure and critical techniques of the system are introduced.2. The measurement principle and mathematical model of the line-structured- light sensor are studied. The structure of industrial robot and the communication of the system are expounded.3. Based on the robot DH kinematic model and the feature of sensor, a new hand-eye calibration method is proposed, using the virtual feature points as the fixed-point. After the robot kinematic model, the robot differential kinematics is analyzed in detail, and robot positioning error model is derived. The robot link parameter errors and the optimized hand-eye parameters are solved by spherical constraint method.4. In order to reduce the registration errors between different point clouds scanned in different robot poses, the iterative closest point (ICP) algorithm is applied for point cloud registration. The ICP algorithm model is analyzed, and the coordinate transformation of different regions is solved by using singular value decomposition (SVD) method. A novel strategy to find the nearest point is proposed, which can improve the convergence speed and matching accuracy of ICP algorithm. In addition, the software of the measurement system is developed. 5. The three-dimensional shape measurement system is built up, based on industrial robot and laser line-scan sensor. The robot calibration experiments are carried out, and the accuracy of the measurement system is evaluated.