Research On Performance Analysis And Structure Optimization Of QR6 Collaborative Robot

With the rapid development of the field of intelligent manufacturing,collaborative robots have quickly become the necessary advanced equipment for intelligent manufacturing due to their advantages of high flexibility and strong human-machine collaboration capabilities.Most of the robot body structures are designed with static strength,which leads to high rotational inertia and low control accuracy,and fracture or fatigue damage when the body structure has process defects.To address the above problems,this thesis adopted the method of combining simulation and experiment.Based on the structural performance analysis and load test of a sixaxis collaborative robot,the fatigue life evaluation and structural optimization design are carried out.The specific research contents are as follows:(1)Based on the D-H coordinate method,the kinematic model of the robot was established,the simulation verifies the correctness of the model,and the workspace of the robot was drawn according to the Monte Carlo method.Based on the Newton-Euler recursion method and the theory of rigid-flexible coupling,a more realistic rigid-flexible coupling model was established.According to the load characteristics and operating conditions,the operating program of the robot was written,and the kinematic and dynamics simulation analysis of the robot was carried out,and the velocity,acceleration,joint force and joint moment time curves of the robot joints and linkages under different operating conditions were obtained.(2)Static analysis of key components under extreme operating conditions was carried out to determine the large stress areas and fatigue life assessment concerns of the body structure,and strain gauges were arranged in the large stress areas and load tests were conducted.Peak and valley extraction and wavelet rejection were performed on the load data,and the stress-load spectra of the joint and linkage structures were compiled by rainflow counting and stress-load extrapolation.(3)The S-N curve of the corresponding robot body structure material ADC12 aluminum alloy was obtained by referring to the method of plotting S-N curve in fatigue analysis software.The S-N curve of the material was corrected by the fatigue integrated correction factor to obtain the S-N curve of the part.Based on the linear cumulative damage theory,the modified symmetric cyclic stress spectrum and the S-N curves of the parts,the fatigue life of each joint and linkage in the robot body structure was evaluated.(4)With the optimization objectives of improving the stiffness of the connecting rod and reducing the structural mass of the whole robot,the dimensions of the connecting rod,joint structure and reducer components are optimized,respectively.By comparing the simulation results before and after the optimization,it is shown that the spatial coordinate error of the endeffector of the optimized model is smaller and the motion accuracy is improved under the premise of satisfying the maximum deformation and material strength limit.