Research On Dynamic Error Modeling And Compensation Of Collaborative Robots

Collaborative robots have been comprehensively used in industrial production and medical fields because of their light weight,safety,and the ability to be a human work assistant.Currently,there are many studies on the positioning accuracy of collaborative robots,but relatively few studies on the trajectory tracking accuracy under dynamic operating conditions.Therefore,studying the elastic deformation error of robots to improve their trajectory tracking accuracy has become a very important topic at this stage.In this thesis,with the support of the National Natural Science Foundation of China(NSFC),we model and compensate the elastic deformation error in the dynamic operation of collaborative robots,establish the mapping relationship between the dynamic error of robots and the kinetic parameters and structural stiffness parameters,and then carry out the dynamic error compensation research.The main work of this thesis is as follows:This thesis firstly establishes the dynamics model of the seven-degree-of-freedom collaborative robot SHIR5 based on the Newton-Euler method,and also considers the influence of gravity,inertial force and Koch force of each joint and linkage of the robot on the collaborative robot under dynamic operating conditions.The required dynamics parameters are obtained according to the CAD identification method,and the robot dynamics model is established by the recursive method using the Newton-Euler method.The ADAMS dynamics simulation software is used to establish a multi-rigid body virtual prototype model of the robot and verify the correctness of the established dynamics model.Then,based on the torsional stiffness and integrated stiffness of the collaborative robot,the corresponding dynamic error models are established and the dynamic errors of the robot are compensated in the joint space.By analyzing the drive system of the collaborative robot joint,the mapping relationship between the joint torsional stiffness and the overall stiffness is established,and the influence of the supplementary stiffness on the overall stiffness is also analyzed to derive the mapping relationship between the supplementary stiffness,the joint torsional stiffness and the end dynamic error.A virtual prototype of the flexible joint is established by using ADAMS software to verify the correctness of the dynamic error model based on the torsional stiffness.The structural stiffness of each joint and linkage of the collaborative robot is extracted using FEM software,and the joint torsional stiffness is combined to establish the comprehensive stiffness model of the robot,and the mapping relationship between the comprehensive stiffness and the end dynamic error is derived.Through simulation experiments,the two dynamic error models are compared and analyzed,and the effect of load change on the dynamic error of the collaborative robot is analyzed through variable load simulation experiments.Finally,the SHIR5 collaborative robot and laser tracker are used to build an experimental platform to achieve real-time high-precision measurement of the dynamic error of the robot.The experimental method of variable load is used to analyze the effect of load on the dynamic error of the robot,and the effectiveness of the two dynamic error models is evaluated by using the Euclidean distance between the load trajectory and the reference trajectory.The average relative error between the trajectory Euclidean distance of the dynamic error calculated based on the integrated stiffness model and the trajectory Euclidean distance of the actual dynamic error is within 10%.