Dynamic Characteristics Analysis And Research On Structure Optimization Of High Speed And Heavy Duty Palletizing Robot

With the wide application of high speed and heavy duty palletizing robot in automobile, metallurgy, logistics and other industries, the automatic production line has higher requirements for the speed, load ability, acceleration and positioning accuracy of the robot. For the high-speed palletizing robot’s operating characteristics of high speed, high acceleration and heavy load,it is not enough to finish the structure design at the kinematic level. It is necessary to make a research on the structure optimization focusing on the vibration characteristics according to the mechanical and dynamic performance analysis. Therefore, considering the working characteristics of high-speed heavy palletizing robot, this paper proposes an optimization design method based on the vibration characteristic analysis of high speed and heavy load palletizing robot.Firstly, based on the D-H parameter method and the second Lagrange equation, kinematics and dynamics analysis of high-speed heavy palletizing robot is carried out and then a flexible dynamics model is built. According to the ADAMS analysis software, the robot virtual model is built, the dynamic simulation is carried out, and the effect of the joint flexibility on the robot performance and the correctness of the dynamic equation are verified. According to the modal analysis theory, mode superposition method is applied to analyze and research the modal superposition method of palletizing robot.Secondly, modal analysis is carried out for three typical poses of the palletizing robot by ANSYS. Calculation results show that in three positions, natural frequency of the robot will be changed to a certain extent, but the vibration mode is basically identical, the lowest order natural frequency is mainly due to the swing vibration caused by the joints flexibility of the big arm. Then through modal analysis scheme of multi-point excitation and single point pick-up, with the help of Bobcat dynamic testing system, the overall dynamic test in typical configurations is carried out and the correctness of the finite element analysis results.Then, considering the effect of joint flexibility, combined with the specific working characteristics of high-speed heavy palletizing robot, based on the analysis of static and dynamic mechanical properties, it has determined that the natural frequency, static stiffness and speed characteristic are as the optimization objectives. The optimized variable is determined by the simplified treatment of the size arm structure and the relative sensitivity analysis of the natural frequency. The coupling relationship between the targets is obtained by optimizing the performance spectrum of target. Combined with the other specific job requirements of palletizing robot, it has established a multi-objective optimization function model and determined that the work space, the maximum acceleration capability and the size of the arm stiffness are as the restriction conditions.Finally, for the existed defects of NSGA-II, the crossover operator and the ranking of congestion are improved, and the effectiveness of the improved algorithm is verified by the typical test function and the performance evaluation index. The optimization model is solved by improving the NSGA-II algorithm, and the optimal solution is selected according to the actual demand. Through the simulation experiments analysis, the performance of each performance has been improved, and the effectiveness of the structure optimization is verified.