Robotic Milling System Development And Experiment

Compared with the traditional way of CNC machining,robotic machining has the advantages of large machining range,good flexibility and low cost.Therefore,it is particularly suitable for machining large workpieces with complex surfaces.However,the robot has the features of poor stiffness and low accuracy,resulting in the precision and surface quality of the workpiece machined by robot are difficult to be guaranteed,hence,the robot is not currently large-scally used in milling field.Therefore,it is important to study the robotic milling technology for complex surfaces machining.After researching the robot subsystem,electrical spindle subsystem and milling force measurement subsystem,the specific device model of each subsystem are determined,and a robotic milling experiment platform is builded as well.By using the MFC,library functions provided by MOTOMAN robot,NI data acquisition card,ATI force/torque sensor,etc.a robotic milling system control software consisting of robot motion control,post-processing,file transfer and milling force online measurement functions has been developed,and tests are conducted to verify its reliability.To improve the absolute positioning accuracy of the robot,a kinematic calibration method for the MOTOMAN robot based on the exponential of product(POE)formula has been studied.The spinor model of MOTOMAN robot is established,and then an error model based on the POE formula is developed,The parameters are identified based on the least squares method.The robot calibration experiment verifies the proposed calibration method and improves its absolute positioning accuracy.A five-axis robotic machining post-processing algorithm is developed.The CLSF files generated by UG can be converted to JBI files which are executable for MOTOMAN robot with the developed post-processing module.Finally,the robotic milling experiment verifes the feasibility of five-axis robotic machining.