Research Of Railway Train Coupler Detecting Assembly Line Based On Visual Measurement

To batch implement 3D inspection for the parts with complex surface, the key technologies such as the camera calibration, integrated measurement system modeling, measurement model parameters calibration and data post-processing etc. are studied. Research results are applied to railway, the automatic detection assembly line for railway train coupler is implemented. The main contributions of the thesis are consist of follows:1. The detection assembly line for railway train coupler is taken as an example to show the designing process for the parts with complex surface batch inspection system, which include mechanical structure of actuator, electronic control system, control software architecture and inspection process of the integrated system etc.2. Using sensor model of line structured light with distortion compensation and two-stage method called as RAC, the sensor measuring model parameters are calibrated. To improve measurement precision, using the artificial bee colony-RBF neural network, the sensor parameters are calculated.3. The kinematics model of actuators and the model of inspection system are given. Then, combining a flexible arm measuring machine and a standard ball with space round fitting algorithm, the presented model parameters are calibrated. Also, based on principle of cross ratio invariance, a fast calibration approach is presented.4. The point cloud data is coded using three-dimensional grid method, and then, based on the principle of regional growth and curvature constant, the noise is filtered so that the data is simplified. According to the PCA algorithm, the preliminary registration is achieved between point cloud data and standard CAD model, then, use the ICP algorithm to improve the registration results.5. The equal precision measurement and unequal precision measurement is respectively used for standard coupler parts and worn coupler parts, and based on inspection results, the inspection accuracy and uncertainty of the railway freight train coupler laser inspection system is concluded, besides that, the sources of inspection error is analyzed eventually. Finally, the further expansion on the research content is listed based on the conclusion of whole work.