Robot Joint Transmission Error Analysis And Compensation Mechanism Research

Articulated robots are typical intelligent manufacturing equipment.With the continuous in-depth application of robots in various segments of the manufacturing industry,the requirements for their motion accuracy are becoming more and more stringent.The robot joint is a mechatronic system composed of a servo motor and a reducer,and its transmission error is the result of the coupling of various factors,which largely determines the motion accuracy of the robot end.Therefore,in order to improve the transmission accuracy of the robot joints,this thesis takes the robot joints as the research object,studies the transmission characteristics of the joints,the generation mechanism and modeling of kinematic errors,the modeling of friction torque and dynamic errors,and proposes a new method for kinematics Compensation method for error and friction torque.The specific research contents are as follows:Firstly,the kinematics and dynamics characteristics of the robot joint transmission are analyzed,and the transmission error is decoupled according to the influencing factors in the transmission process: the kinematic error caused by the machining and assembly errors of the joint manufacturing process,the hysteresis of the reducer,and the Dynamic errors caused by the coupling of nonlinear friction disturbances and nonlinear hysteretic stiffness characteristics.Then,aiming at the kinematic errors caused by the machining and assembly errors of the robot joints,the error sources such as the machining errors and assembly errors of the flexible wheel,the rigid wheel and the wave generator and their coupling effects on the kinematic errors are comprehensively analyzed,and the joints are established.The kinematic error synthesis model based on the proposed method solves the problem of inaccurate low-frequency error prediction in the single-error linear superposition model;a model optimization method based on trigonometric function and differential product method is proposed,which simplifies the difficulty of parameter identification,and designs a joint kinematics error test.Experiments have verified the accuracy of the coupled error model.Aiming at the nonlinear friction of robot joints,the influence of rotational speed,lubrication effect,machining and assembly errors on the nonlinear friction characteristics during the operation of the joint is analyzed,and the nonlinear friction torque related to the joint input rotational speed,motor rotation angle and joint rotation angle is established.The parameters were identified through the joint friction torque experiment,and the accuracy of the nonlinear friction model was verified.The nonlinear hysteresis characteristic of joint stiffness,which is the main influencing factor of joint dynamic error,is studied,and the relationship between torsion moment and torsion angle is obtained through dynamic error test experiments.The dynamic error model is established by using the hyperbolic function,and the model parameters are identified,which realizes the accurate description of the stiffness of the robot joints.Finally,aiming at the compensation mechanism of the robot joint transmission error and friction torque,the offline position error compensation and fixed friction model compensation methods are adopted,and the effectiveness of the compensation method is verified through the position error compensation experiment and the zero-force control experiment.This thesis realizes the description of the robot joint error by establishing the kinematic error,nonlinear friction,dynamic error and other models,and proposes an offline error compensation method and a fixed friction model compensation method for various coupling errors,which improves the robot joint transmission.It reduces the nonlinear friction interference in the process of joint motion,thus providing a reference for improving the motion accuracy of the joint robot and expanding its high-precision applications.