Dynamic Structure Topology Optimization Of Automotive Spraying Robot

Spraying robots have great advantages in terms of flexibility,spraying quality,spraying efficiency,and coating utilization,and occupy an important position in the field of automotive coatings.Aiming at the strict requirements of paint film thickness and paint film uniformity of automobile surface coating,simply considering the structural optimization design under static force cannot meet the requirements of spraying process well.In order to further improve the trajectory accuracy and spraying quality,it is necessary to take into account the influence of dynamic forces on the deformation of the tip during the spraying process,and carry out structural topology optimization design under the dynamic force of the spraying robot body structure.In this paper,the self-developed 7R 6-DOF spraying robot is used as the research object.The kinematics model of the spraying robot is established by using the D-H parameter method.Based on the mass and inertia properties of the actual spraying robot prototype,a Newton-Euler method was used to establish the robot’s dynamic model and a MATLAB program was written.The ADAMS software dynamic simulation analysis indirectly verified the correctness of the program,and provided a theoretical basis and calculation method for the subsequent calculation of the inertial force and moment of each member.Then based on the real spray teaching points of the car,the continuous spray trajectories at the car roof,front cover and door were obtained by means of position interpolation and posture interpolation.Based on the six-degree-of-freedom kinematics inverse solution,the angle,angular velocity,and angular acceleration of each joint over time were obtained.Finally,the previously prepared MATLAB program was used to calculate the magnitude and direction of the inertial force and moment of each link during the robot spraying motion.According to the different spraying areas,robot poses and inertial forces and moment directions,the three working conditions of the top cover,the front cover and the door were studied respectively.It is found that the inertial force and moment are large at the turning points of adjacent trajectories.Therefore,several pose points are selected at the turning points of adjacent trajectories and the ABAQUS software is used to quantitatively calculate the terminal deformation of the whole machine.A dangerous working condition is selected at the top cover,the front cover and the door as a typical working condition of the subsequent topology optimization design.Finally,Hyper Works software was used to optimize the structure topology and model reconstruction of the robot’s forearm,forearm,and waist under dynamic conditions.In order to expand the solution space of the optimization variables,the interior of the parts to be optimized is filled as the initial structure.The static deformation under typical working conditions is the constraint condition,and the volume fraction is minimized as the objective function.The structural topology optimization and 3D model reconstruction under the action of dynamic forces are presented.By comparing the deformation of the components before and after the optimization and the end of the whole machine and the first five natural frequencies of the whole machine,the dynamic performance is further improved and the structure is more perfect.