Optimization Design Method Research Of High-speed Serial Industrial Robot

With the demand for industrial upgrading, the intelligent equipment represented by industrial robots is playing a more and more important role and industrial robots have great significance in the industrial automation, intelligence and labor shortage. By the improvement of product quality and production efficiency, the industrial robot must meet the higher demand in the stability and movement precision. In order to meet performance requirements, such as high-speed, in the view of the kinematics and dynamics analysis on the mechanism, the dynamic design method is used to constantly optimize the parameters to meet the dynamic requirements of high speed and high precision in the design phase of the industrial robot body. The research carried on the work of kinematics modeling and rigid body dynamics modeling of the industrial robot with high performance on the basis of the national 863 plan project “ Development platform combined with the industrial robot design upon CAD/CAE technology”, and optimized its mechanism according to the proposed kinematic and dynamic index and its structural parameters according to its flexible joints and flexible connecting rods. After above optimization, a 6 DOF serial industrial robot prototype was developed and verified the results of optimization design.First of all, the research analyzed the initial structure of the common 6 DOF serial industrial robot kinematics and built a kinematics model of industrial robot according to the DH method and deduced the analytical expressions of robot terminal’s position, velocity and acceleration. The industrial robot kinematics index, put forward by the kinematic characteristics, was used as the objective function of mechanism optimization. Then, the rigid dynamical model was built according to Lagrange equation and its dynamical equation was validated by using the simulation software ADAMS. The rigid dynamical index was put forward and structure parameters’ optimization model was built based on the model mentioned before, design variables of which are length and sectional area of the connecting rods, objective functions of which are dynamical indexes such as inertia and drive torque of links. The process of the structure parameters’ optimization is completed by using NSGA-II under the given constraint condition.An optimal design method proposed for structural parameters of the industrial robot, considering both flexibility of links and joints, aims at some obvious feature problems of high performance industrial robots of the flexibility in the situation of high speed. The robotic links was discretized firstly based on the Bernoulli-Euler beam model of finite element method, then the flexible-body dynamical model of the industrial robot was built by Lagrange equation and optimized for the flexible mechanical arm model built taking the maximum first-order natural frequency and the maximum load weight ratio as its performance evaluation. The multi-objective optimization problem was solved by the NSGA-II algorithm so that its Pareto solution set of the optimization goal was obtained.On the basis of the above analysis and optimization design, the robotic body parameters were determined, such as the length and sectional area of bars, and the robotic key components were chosen, such as motors and reducers, so that an industrial robot prototype were processed. It was to verify the parameters’ optimization design of this industrial robot that the prototype was processed a modal experiment and tested its first-order natural frequency which had been compared with another natural frequency calculated by the optimization model mentioned above, and the experimental results verified the feasibility of the flexible dynamical simulation and the accuracy of the model. Meanwhile, in order to verify the kinematic accuracy of the high-performance industrial robot designed, its repeatability, distance accuracy and distance-repeatability were all measured. The feasibility of the proposed method was proofed, and the industrial robot designed in this research met the design requirement of position accuracy.