Static Stiffness Analysis And Optimization Of Drilling And Riveting Robot

Industrial robots have the advantages of low cost,high flexibility and high intelligence,which are widely used in the field of aircraft assembly and manufacturing.Modern aircraft has higher standards for life and performance,which correspondingly puts forward higher requirements for aircraft assembly quality.However,the inherent characteristics of the weak rigidity of the human structure of the tandem manipulator make it have the problem of deformation in the process of processing,which is often the case It will lead to insufficient machining accuracy and quality of the system,and even flutter.Therefore,it is of great significance to obtain the static stiffness parameters of the robot and to study the optimization methods to improve the stiffness performance,so as to ensure the stability of the robot system and improve the machining quality of the system.In view of this,this thesis takes the drilling and riveting robot as the object,and carries out the research on the static stiffness modeling and parameter acquisition of the robot,the stiffness performance analysis in the workspace,and the pose optimization based on the stiffness performance.First,based on the modified DH parameter method and the principle of homogeneous coordinate transformation,the kinematics model of the robot was established,and the correctness of the model was verified in the Matlab robot toolbox.The robot kinematics positive solutions is deduced,using the differential transform method the Jacobi matrix is constructed.Based on the Jacobi matrix,the assumption that connecting rod under the condition of rigidity,operating stiffness at the end of the robot joint stiffness and mapping relationship,eventually robots static stiffness model is established,and the robot operating stiffness position related conclusion.Secondly,Using laser tracker and six dimension dynamometer high precision measuring equipment,designed and completed the robot joint stiffness identification experiment.Based on the experimental data processing,access to static stiffness parameters of the robot joint stiffness values.With an additional two sets of data on the stress of the robot end deformation situation made a prediction,and compares the actual deformation discovery can well match,so as to identify joint stiffness value is verified by the effectiveness and accuracy.Then,analyzed the nature of the stiffness matrix operation,and introduces the matrix Rayleigh entropy,ellipsoid of deformation and force ellipsoid three stiffness performance evaluation index.By using the monte-carlo simulation to get the robot working space,and ellipsoid of deformation and force ellipsoid parameters as the rigidity of performance indicators,the robot working space stiffness performance simulation with cloud,choose the optimal stiffness performance test to guide the robot area is given.Finally,aiming at the maximization of the rigidity performance,combined with the pose constraints of the robot drilling and riveting system,the mathematical model of the pose optimization problem based on the rigidity performance of the robot is established,and the particle swarm optimization algorithm is used to solve the optimization problem.Combined with a specific example,it is proved that the purpose of enhancing the rigidity performance of the robot is realized by optimizing the pose of the robot.It is of great significance to ensure the stability of the robot system and improve the machining quality of the system.