Modeling And Analysis Of The Dynamic Flexibility On The End Of Robotic Milling Workspace Under Movement Excitation

Industrial robots are used more and more in all walks of life due to their low cost and wide working space.Mechanical processing using industrial robots is one of them.The factors that determine the processing capability of the robot include its terminal stiffness and terminal dynamic characteristics.Increasing the terminal stiffness can improve the processing accuracy of the robot,optimize the terminal dynamic characteristics and reduce the vibration during the processing to improve the processing quality and extend the life of the parts.However,industrial robots often depend on the structure characteristics of their multi-degree-of-freedom cascades,which leads to the dependence of their terminal dynamic characteristics.The dynamic characteristics and processing capabilities on the end in different working areas vary greatly.The establishment of the robot end dynamic characteristics analysis model related to the joint angle is the basis for studying and improving the robot end's dynamic characteristics.Firstly,combined with the characteristics of the robot's joint,a dynamic model of the robot's joint is established,and the working modal analysis of the robot's joint is performed by self-excitation.Based on the least squares complex exponent method,the robot joint modal parameters are identified,and the modal parameters of the robot's different joint are effectively obtained.Secondly,the model of relative dynamic flexibility of the milling end of the robot in the workspace is established.Based on the exponential product method,the kinematics equations of the robot are established,the dynamic characteristics of the robot milling end expressed by the joint angle and the relative frequency response function of the joint are derived,and the relative dynamic flexibility model of the end of the robotic milling process in the joint space is established.Through the inverse kinematics of the robot,the mapping relationship between the position space,the attitude space and the joint space is established,and the relative dynamic flexibility model of the end in different spaces is obtained,and the experimental verification of the relative dynamic flexibility model of the robot milling end is carried out.Thirdly,the OMA method of cutting excitation is used to study the dynamic characteristics of the milling robot end.Establish a random pulse cutting excitation model,and analyze the influence of different processing parameters on the excitation signal energy and bandwidth.An improved nonlinear optimized modal parameter identification method is proposed.Carry out different forms of milling robot cutting excitation experiments,effectively obtain the equivalent stiffness in the frequency response function of the robot end.In the last,based on the analysis of the established milling robot end relative dynamic flexibility model,the pose is optimized.Analyze the distribution rule of relative dynamic flexibility of different space of milling robot ends,and put forward the optimization methods of position space and attitude space parameters,perform the optimization calculation of multiaxis parallel milling robot posture.The dynamic characteristic analysis model of the robot milling process established in this paper can provide a direction for the research of robot milling vibration and reduce the vibration in actual processing,which has high significance in theoretical research and engineering applications.