Dynamic And Static Performances Analysis Of A Novel High-Speed 6-DOF Parallel Robot For 3C Industry

In 2022,the total output value of 3C(Computer,Communication and Consumer electronic)industry of China has exceeded 5 trillion yuan.However,low level of automation is gradually becoming a constraint to the development of the industry.Due to the high stiffness,strong bearing capability,high accuracy,high working speed and flexible posture of high-speed six degree-of-freedom(6-DOF)parallel manipulators,it has been considered as the optimal solution for the 3C industry to achieve an automation upgrade.At present,there are only a few high-speed 6-DOF parallel manipulators can be applied to the 3C industry.The research of this field in China is still in the preliminary stage,and still facing the following problems: 1)The structures of traditional high-speed6-DOF parallel manipulators are complex and the workspace of them are small,and the technology patents are monopolized by the foreign countries.2)There is a lack of systematic dynamic and static performance analysis methods and performance evaluation indices with clear physical meaning of high-speed 6-DOF parallel manipulators.3)The dimensional design of high-speed 6-DOF parallel manipulators is mostly based on experience and imitation,and lacks a rigorous mathematical basis.In this thesis,based on the above background and problems,a new high-speed 6-DOF parallel manipulator is studied in terms of its mathematical modeling method,dynamic and static performance analysis method and multi-objective dimensional optimization design are investigated based on this.The specific research content of this thesis is as follows:Combining the practical requirements of high-speed,high precision and large working space in the manufacture of 3C products,a novel 6-DOF parallel manipulator with only three limbs for high-speed operations is presented in this thesis.Then,a complete kinematic model of the manipulator is established,which includes the inverse position,the closed-form forward position model,the velocity and acceleration models of the manipulator.At last,the correctness and validity of the complete kinematic model of the manipulator is verified by simulation experiments.The workspace and singularities of the manipulator are analyzed.The conditions for the occurrence of singularities of the new manipulator are presented.The search method for the workspace of the manipulator is presented,and the definition of the recommended workspace is given.Then the recommended workspace of the new manipulator is compared with that of the traditional HEXA type parallel manipulator in the same dimensional parameters.The volume of the recommended workspace of the new manipulator is 3 times larger than that of the HEXA type manipulator.In addition,a new method to represent the complete workspace of 6-DOF parallel manipulators is proposed by introducing the RGB color coordinate,and a three-dimensional(3-D)representation of the complete workspace of the new manipulator is given.A complete dynamic model of the manipulator is established,and the dynamic equations and the inertia matrix of the manipulator are deduced in the joint space.Moreover,a simulation experiment is given to verify the correctness and validity of the complete model.Then,based on the inertia matrix in joint space,a new dimensionless dynamic performance evaluation index is proposed,which can directly reflect the acceleration capability of 6-DOF parallel manipulators,and considered the coupling relationship among all the actuators of the manipulator.The distribution of the new index is presented with different position and posture parameters of the manipulator,and the regularities of the distribution of the new index and the acceleration capability of the new manipulator in its workspace are analyzed.An accurate static stiffness modeling method for 6-DOF parallel manipulators with a closed-loop structure in its limbs is proposed.Then,a simplified modeling method for this type of parallel manipulators is proposed,and the analytical expressions are given.Moreover,considering the coupling relationship between external force and moment loads,a new static stiffness performance evaluation index is proposed,which is not affected by the choice of the coordinate system.At last,a simulation experiment is presented to verify the correctness of the two stiffness modeling methods.In addition,the regularities of the distributions of the new index obtained by the two methods in the same plane is compared,which verified the validity of the simplified modeling method.Based on the actual requirements of 3C industry,the workspace volume,acceleration capacity and static stiffness performance are selected as the core indices and the objective function is constructed.The NSGA-II algorithm is used to optimize the dimensional parameters of the new manipulator,and the multi-objective Pareto frontier of the new manipulator is obtained.Finally,the dimensional parameters in the Pareto optimal solution set are optimized,and the dimensional set of the new 6-DOF parallel manipulator with excellent dynamic and static performance is obtained.