Control Method For Robot Polishing Complex Workpieces Without Geometric Information

With the advancement and development of intelligent manufacturing technology,industrial robots are increasingly widely used in industrial field.In recent years,industrial robots have been more and more widely used in machining such as polishing and grinding.However,at present,the polishing and grinding of complex workpieces without geometric information still rely heavily on manual operations,so the automaticity of polishing and grinding is still low.As the last process of traditional machining,polishing and grinding have an important influence on the surface quality of workpieces.Using robots to implement the automatic polishing of workpieces with complex surface,which helps solve problems such as harsh environment in manual polishing and labor shortage caused by population aging.In this paper,a control system is designed and developed for the application scenarios of the robotic polishing of complex workpieces without geometric information,and then a series of issues involved in this basis are studied.A macro-mini robot polishing platform and its control system are designed and developed.The system includes a polishing end effector with active force control,which has the advantages of low inertia,high response,and high control bandwidth.The polishing end effector(mini robot)and industrial robot(macro robot)form a macro-mini robot polishing system,which realizes the decoupling of contact force control and robot position control.The force signal from the six-axis force sensor is collected and preprocessed.According to the contact model between polishing tool and workpiece,the force of the polishing end effector is analyzed,then the zero calibration and gravity compensation method of the six-axis force sensor is proposed.The method enables the system to accurately measure the contact force between the polishing tool and the workpiece.A series of experiments are designed to verify the correctness of the compensation algorithm.In these experiments,the accuracy of the compensation algorithm is analyzed respectively when the robot in the stationary and moving state.Based on the contact force and contact state analysis in robotic polishing of workpieces without geometric information,a robotic polishing control strategy is proposed.This method can use the contact force as feedback information for control to make the end effector spindle direction can always follow the normal direction of workpiece surface at the contact point,while maintaining a constant contact force.Then a series of polishing experiments are designed,in which surface workpieces with various materials and various shapes are used,which fully verify the effectiveness and adaptability of this method.In these experiments,the normal tracking accuracy,force tracking accuracy,and surface roughness improvement are also analyzed.Finally,the effects of polishing parameters,such as contact force,spindle speed,and feed rate on the surface quality of workpieces are studied through experimental methods,and the effect of different polishing parameters on the surface roughness of the workpiece is qualitatively given.This provides a foundation for the real-time detection of the surface quality of the workpiece and polishing parameters adjustment online in the future.