Kinematics Modeling And Parameter Optimization Design Of 3-RPRU Parallel Robot

With the development of science and technology,robots have been widely used in industrial,civil and military fields.The emergence of robots greatly improves work efficiency,liberates manpower,and can effectively solve tasks that are difficult to be completed by humans,especially in dangerous environments.The series robot has flexible operation and large workspace.It has been widely used in welding,spraying and handling.But this kind of robot has many limitations such as low load,low stiffness and error accumulation due to its structure.Parallel robots have obvious advantages such as strong load capacity and high stiffness,and have been widely used in complex fields such as aerospace and large ship manufacturing at present.Due to the existence of multiple branch chains and a large number of joints,the kinematics modeling and system parameter optimization of parallel robots are more difficult,especially the optimization of structural parameters has become the focus of attention.In this paper,a linear driven 3-RPRU parallel robot is taken as the research object,and its kinematics theory and mechanical properties are systematically and deeply studied.The main research contents and achievements are as follows:(1)Research on Kinematics Theory of 3-RPRU Parallel Robot.In this paper,the improved D-H method is used to deduce and establish the kinematics model of the robot,analyze the kinematics constraint relationship between the input and output components,the kinematic model is simulated by ADAMS to verify the correctness of the kinematic model.(2)Based on the robot configuration and kinematic constraints,the workspace was solved and optimized.Monte Carlo method was used to calculate the robot workspace.The maximum volume of the workspace was taken as the optimization objective,and the optimal parameters of the mechanism were obtained by the genetic algorithm.The results show that the optimized workspace of the robot reaches 1.75m3,which is increased by 92.31% compared with 0.91m3 before optimization,greatly improving the workspace of the robot.(3)In this paper,the mechanical properties of 3-RPRU parallel robot are analyzed and the parameters of the rod are optimized.In order to improve the mechanical properties of the parallel robot and to increase the load capacity and motion stability of the mechanism,the response surface optimization of the cross section dimensions of the parallel robot was carried out with the objective of minimizing the mass,the maximum equivalent stress and the maximum equivalent strain of the mechanism.The numerical simulation results show that the overall mass of the optimized mechanism is reduced by 4.49%,the maximum equivalent stress by24.41%,the maximum equivalent deformation by 22.98%,and the maximum displacement by 23.73%.On the basis of reducing the mass of the mechanism,the deformation resistance and load capacity of the mechanism are effectively improved,and the operation accuracy of the mechanism is also improved to a certain extent.The proposed method and related data provide important theoretical basis for the parameter optimization design of this kind of robot.