Kinematic Modelling And Cycle Optimization On Heavy-Load Manipulators

With the application of the high-speed heavy robots in the auto,metallurgy,logistics industry,higher demands on the speed,load capacity and positioning accuracy of the robots need to be met in the automatic production line.Because of the motion characteristics of the high-load,high speed and accuracy of the robots,analysis and design based on the kinematics is not enough.Research on the structure design of the robot based on the dynamic characteristics is essential together with the dynamics and statics.In the paper,the dynamic characteristics of the heavy robots are improved effectively by counter-balance design,structure optimization and dynamical analysis.And a trajectory planning method based on an elliptical curve is proposed to improve the motion speed and eliminate the vibration of the heavy robots.Firstly,the workspace of the robot is determined by the working condition.After the pre-design of the mechanical parameters of the robots,the kinematic and dynamic model is expressed using the D-H parameters and Lagrange equation(of the 2nd kind).Considering the factors of the mass,damping and inertia,the model is transformed to a linear-matrix-inequality optimizing problem based on the energy-minimized principle.The optimized physical parameters are determined.In the same time,the motion nonlinear and motion coupling problems under the situation of the heavy load are studied based on the dynamic equation.Using this method,the mechanical design and proper weight of different parts are achieved.And the design and calculation of the counter-balance mechanism is completed.The correctness and effectiveness are verified by the simulation.Secondly,the general layout of the control system is given.And using the servo feedback technology,the motion accuracy of the robot joints are adjusted in real time.By the colla'borated planning algorithm of the joint motion space and Cartesian space,the speed and accelerating curve are kept continuous during the working process.A good dynamical characteristic of the robots is achieved under the condition of the high-load and high-speed.Finally,the multi-objective optimized model is resolved and the optimized results is analyzed.By the analysis on the vibration problems while running,an elliptical trajectory planning method is proposed to eliminate the vibration andsmooth motion trajectory.The optimum solution is achieved based on the actual demands.The effectiveness is proved by simulation analysis and working experiment of the robot.The optimized results show the motion characteristics are improved.