Calibration Of Dual-Robot Skin Mirror Milling System And Collaborative Processing Path Generation

The skin mirror milling is a new green technology for the processing of aerospace skin panels that has emerged in recent years.It uses point-topoint local follow-up support during the processing to improve the rigidity of the process system.The existing skin mirror milling equipment is mostly based on a dual five-axis horizontal gantry machine structure,which is large in size and poor in flexibility.The dual-robot skin mirror milling system has the advantages of high movement flexibility,large working space,and strong parallel coordination ability,which provides a new way for efficient and precise processing of large skin panels.In this paper,related researches are carried out on the kinematic calibration and collaborative processing trajectory generation of the dual-robot skin mirror milling system.First of all,the structure of the dual-robot skin mirror milling system is introduced in this paper.The forward and inverse kinematics models are established for the hybrid robot on the processing end and the serial robot on the support end,which provides a theoretical basis for dual robot calibration and collaborative processing trajectory planning.The dual-robot collaborative processing trajectory is generated by offline programming,which requires high absolute positioning accuracy.Kinematics calibration is an effective method to improve the absolute positioning accuracy of the robot.In this paper,a new kinematic calibration method is proposed for six-axis serial industrial robots based on a single telescoping ballbar.A simulation study demonstrates that the proposed method is effective and robust.The relative pose between the two robots base frame needs to be determined before the trajectory planning of the dual-robot collaborative processing.In this paper,two dual-robot base frame calibration methods are proposed,and the calibration effects of different methods are analyzed and compared.Aiming at the dual-robot skin mirror milling system,a higherprecision calibration method is used to carry out a dual-robot base frame calibration experiment,and the relative pose between the dual-robot base frame is determined.Aiming at the trajectory of dual-robot skin mirror milling,considering the clamping deformation of the parts,a dual-robot mirror milling trajectory planning method based on ultrasonic measurement and surface reconstruction is proposed in this paper.Firstly,the ultrasonic sensor on the support head of the supporting robot is used to obtain the point cloud of the deformed workpiece after clamping and reconstruct the 3D model of the deformed workpiece,and the processing trajectory is planned based on UG.Then,according to the kinematic constraints and synchronization requirements of the dual robots,the trajectory post-processing algorithm is programmed to obtain the cooperative processing trajectories of the processing end robot and the supporting end robot respectively.