| As the main direction of national manufacturing power strategy,intelligent manufacturing is an important turning point for China to move from a big manufacturing country to a strong manufacturing country.In the field of equipment manufacturing,with the development of modern advanced intelligent manufacturing technology,online measurement technology for manufacturing field has been widely used.Among them,the flexible measurement system with industrial robot as the moving carrier and structured light sensor as the detection device has the advantages of non-contact,high efficiency and high precision,which can better meet a variety of online measurement needs in the industrial field.The flexible measurement system based on structured light sensor is composed of industrial robot and linear structured light sensor,and its measurement principle is as follows:The industrial robot drives the structured light sensor to scan the workpiece to be measured,and the feature point information of the workpiece is extracted according to the measurement requirements.Then,the feature point information is converted to the robot base coordinate system combined with the hand-eye relationship and the robot terminal pose information,and the corresponding machining offset trajectory is generated according to the feature point information after 3D reconstruction.Finally,the trajectory guidance requirements of the machining path of the robotic automatic milling system are realized.Before realizing the measurement function,it is necessary to calibrate the hand-eye relationship between the robot and the linear structured light sensor,and then realize the feature extraction and offset trajectory generation.Therefore,this paper adopts the following ideas to carry out the research on relevant calibration and measurement technology:(1)Firstly,the hand-eye relationship model is established,and the hand-eye calibration method based on fixed-point pose change is introduced.Then,a new strategy to reduce the calibration error of industrial robot hand-eye calibration by using combinatorial optimization method is proposed,and a sphere loss criterion to measure the calibration result is defined,and the parameters of hand-eye relationship are modified by using singular value decomposition.(2)Then a slope method with threshold control is given to indirectly extract different types of features,and the processing steps and methods after the 3D reconstruction of feature point cloud are given.The generation principle of offset trajectory is introduced,and the corresponding calculation method is given.(3)Based on the principle of hand-eye calibration and measurement,the hardware and software modules of the system are designed and implemented,and the corresponding human machine interface interaction interface is developed.(4)Then the hand-eye calibration experiment is carried out,and the results show that the spherical mean square deviation is reduced from 0.007 mm to 0.003 mm,and the radius deviation is reduced from 0.055 mm to 0.017 mm.Then the lateral and longitudinal measurement accuracy experiments of the system are carried out,and the results show that the relative error of the lateral measurement is less than 1%,and the relative error of the longitudinal measurement is less than 5%.(5)Finally,the calibration and measurement experiments were carried out in the real workshop environment,the edges of the front hatch door surface and the modeling surface of MA700 aircraft are scanned,and the edge features are extracted and reconstructed.Based on the reconstructed edge features,the motion trajectory of the milling cutter with the specified offset distance is successfully generated,and the trajectory guidance requirements of the robotic automatic milling system are completed. |
