| Industrial robots have the advantages of high flexibility,large workspace,flexible pose control and low cost.Applying them to cutting processing can adapt to the requirements of modern production modes of multi-variety,small batch,and on-site processing.It can significantly reduce production costs,improve the utilization rate of equipment and processing space,and has a broad application market and development potential.At present,industrial robots have been widely used in handling,welding,assembly and other fields,which has greatly improved the automation level of the manufacturing industry.However,compared with the above applications,industrial robots are less used in the field of metal cutting.Due to the special multi-bar series structure of the robot,the weak stiffness characteristic becomes the primary factor affecting the machining accuracy of the robot.The weak stiffness characteristic makes the robot end easily deformed during the cutting process,which in turn affects the positioning accuracy and machining accuracy of the robot,which greatly limits the application and promotion of industrial robots in the machining field.To improve the machining accuracy of the milling robot,this thesis comprehensively considers the influence of joint deformation,arm deformation and arm gravity on the deformation of the robot end,establishes the overall stiffness model of the robot,and studies the error compensation method of the milling robot.The main research contents of this thesis are as follows:(1)The kinematic model of the 6-DOF robot was established.Through the analysis of the structure and workspace of the ES165 D robot,its D-H kinematic model was established,the forward and inverse kinematics equations of the robot were deduced,and the Jacobian matrix of the robot was constructed,which was verified by the MATLAB robot toolbox.(2)The overall stiffness model of the 6-DOF robot was established.Considering the influence of joint deformation,armbar deformation and armbar gravity on the end deformation of the robot,the overall stiffness model of the robot under different postures is established,and the established stiffness model was verified by the end deformation measurement experiment.The results showed that the average absolute percentage error between the experimental results and the simulation results of the comprehensive deformation of the robot end is less than 15%,which proves the accuracy of the overall stiffness model of the robot.In addition,the influence of each joint angle on the overall stiffness of the robot(end stiffness)is analyzed through the established robot overall stiffness model.It is concluded that the output angles of the 2 and 3 joints of the robot were the main factors affecting the overall stiffness of the robot.(3)The parametric modeling of the overall stiffness of a 6-DOF robot was carried out.Based on the overall stiffness model and parametric modeling idea of the robot,the parametric calculation interface of the overall stiffness of the 6-DOF robot was developed by using the software design function of MATLAB(App Designer).YASKAWA ES165 D and COMAU SMART5 NJ220 were used to verify the human-computer interaction interface of the overall stiffness calculation of the robot,which proved the correctness and versatility of the established human-computer interaction interface.(4)The error compensation method of the 6-DOF robot was studied.The instantaneous rigid force model in the robot milling process was established,and the error compensation method of the robot was studied.The error compensation man-machine interface of the robot in the milling process was developed by using the software design function of MATLAB.The error compensation method in this thesis is verified by the error compensation experiment.The average distance error of the machining path after compensation was reduced by more than 30% compared with that before compensation,which showed that the error compensation method in this thesis has a certain compensation effect. |
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