| The joint flexible deformation error and its transmission and accumulation of a multi-joint serial robot due to a large load are the main sources of absolute positioning error of the robot,and also one of the basic problems that need to be solved in the robot field.As the manufacturing process places higher and higher precision requirements on robots,as production cycles become shorter and tasks are updated frequently,online error compensation methods have become one of the important research directions.Although the traditional error off-line compensation method can improve the absolute positioning accuracy of the terminal,it will also cause a prolonged production cycle.Development of online compensation methods must consider the constraints of the robot's operating process and the surrounding environment on the measurement methods.In recent years,the experimental platform of the robot open source controller has provided the possibility of real-time measurement of the drive current of the underlying joints.To this end,by systematically analyzing the relationship between the stiffness of the robot system and the absolute positioning error,an online compensation strategy for robot joint flexibility error based on the current loop data of the joint driver is proposed to achieve effective identification of the state of the work load and its effect,reaching a wide range of The purpose of suitability.In this paper,the flexibility of the robot joint is first analyzed.By establishing the electromechanical coupling model of the robot's flexible joint,the relationship between the mechanical stiffness and servo stiffness of the flexible joint under the position loop is analyzed,and simulation verification is performed.Then,the system stiffness of the robot is modeled,and its mechanical stiffness and servo stiffness models are established respectively,which provides conditions for subsequent identification of joint stiffness and online compensation of joint flexibility errors.Based on the established mechanical stiffness model of the robot body,the robot joint stiffness identification model is further established by measuring the robot end position error.After the robot joint stiffness identification interval is optimized,the joint angle that can effectively express the robot joint stiffness parameter identification is selected.The numerical simulation experiment was carried out,and the identification results in the numerical simulation experiment were verified to ensure the accuracy of the model.By modeling and analyzing the dynamics of flexible joint robots,and combining the characteristics of the open source controller of the robot to provide the underlying joint drive current in real time,a strategy for online compensation of robot joint flexibility errors is proposed.Simulation of the compensation strategy is carried out for the TA6-R3 robot.And based on the MATLAB / GUI platform,a simulation platform for online compensation of robot joint flexible errors was developed.Through the decomposition method of the robot transmission system,the rigidity of the robot transmission components is converted,and the theoretical calculation value of the joint stiffness of the TA6-R3 robot is obtained.Based on the MATLAB / Simulink platform,an online compensation model and algorithm program for robot joint flexibility errors were established.The TA6-R3 robot was used as the experimental object,and three sets of control experiments were carried out on the robot without load,load,and load with compensation.The method proposed in this paper effectively reduces the end error of the robot in the loading direction. |
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