Kinematic Accuracy Analysis And Reliability Optimization Of Special Series Manipulator Under Multi-factor Coupling

The special series manipulator is the key mechanism to carry the model in the special test,which undertakes the important task of stabilizing position and adjusting posture.A series manipulator with a large number of components and joints will inevitably be affected by various error factors.These errors will be reflected in the movement of the actuator at the end of the mechanism,especially the cumulative errors,which will continue to stack with the increase of the service cycle of the mechanism,and even cause the failure of accuracy and reliability.In view of the coupling of multiple error factors,this paper focuses on the cumulative factors,analyzes the response of the kinematic accuracy and reliability of the special series manipulator to the error,and optimizes the accuracy distribution and reliability.First,The forward and inverse kinematics solutions of the series manipulator were established by the analytic method and the exponential product formula based on the screw theory.The modeling process and calculation complexity were simplified,which was the theoretical basis for analysis of the kinematic accuracy and reliability.Secondly,based on the effective length theory,L-N contact model,Archard wear model and other theories,the structural errors caused by the clearance of rotating pair,the clearance of moving pair and the wear of joints were analyzed,and the kinematic accuracy model of the end actuator of the manipulator considering the basic size error,the clearance,the wear of joints and the coupling was established respectively.Then the accuracy error was embedded into the whole system error model to get the accuracy of six directions.MATLAB and ADAMS were used to simulate and analyze the kinematic accuracy,and the influence of each error factor and each joint in the service cycle of the mechanism was obtained.Then,based on the analysis of kinematic accuracy,combined with the stress-strength interference theory,the reliability equation of kinematic accuracy of special series manipulator with various error factors and coupling conditions was derived by the FOSM reliability calculation method,and the solution was carried out to verify the importance of cumulative factors and identify the subsystem to be optimized.Finally,the sensitivity analysis method based on DOE was used,with all error sources as factors and the kinematic accuracy reliability of the end actuator as response.The contribution degree of each factor was obtained and key factors were identified.Aiming at the precision cost and reliability,a hybrid optimization strategy model combining DOE and multi-objective optimization algorithm was established in Isight,which was used to optimize the targets,reasonably distribute the error accuracy,save the cost,and achieve the optimal matching of accuracy cost and reliability.