Research On Motion Reliability Of Robot Based On Improved Fourth-Order Momentestimation Method

The robot's end pose error affects the accuracy of the end positioning.It is important to study the robot motion reliability for its normal operation.Through the robot motion reliability evaluation,the reliability of the robot and the sensitivity of each parameter become an indispensable part of the robot design and optimization.There are many factors that affect the accuracy of the end pose during the working process of the robot.As a result,the actual trajectory of the robot end deviates from the ideal trajectory,making the robot unable to meet the working requirements.Therefore,ensuring the reliability of robot motion has become a top priority for robot design.In this paper,a method for estimating the motion reliability of robot based on improved fourth-order moment estimation method is proposed.The improved fourth-order moment estimation method combines the mean,variance,skewness and peak value.Iterative method is used to optimize the Lagrangian multiplier,which reduces the influence of special individuals,greatly reduces the hypothesis deviation,and has higher calculation accuracy and accuracy.Can be applied to both series and parallel robots,and is suitable for reliability calculation of any distribution type,which greatly reduces the hypothesis deviation and is more in line with the reliability requirements of industrial robots.The relative fourth-order moment estimation method has progress.At the same time,the parameter sensitivity of the robot is solved,and the optimization target is determined to facilitate subsequent optimization.The main contents of this paper include:(1)By introducing the principle of equivalent extremum,the limit state function of the robot is deduced,the probability density function model is established,and the Lagrangian multiplier method is introduced to optimize the Lagrangian multiplier and bring it into the probability density function model to obtain an improved fourth-order moment reliability evaluation model to solve the reliability of the robot.(2)In order to analyze the influencing factors of the motion reliability of the series six-axis welding robot,the factors affecting the motion reliability of the series six-axis welding robot are determined.The kinematics model of the series six-axis welding robot is established,and the forward kinematics and inverse kinematics analysis are carried out.The reliability of the series six-axis welding robot is evaluated by the modified fourth-order moment method by the set trajectory combined of the series six-axis welding robot.(3)In order to analyze the influencing factors of the new 2SPR-2RPU parallel mechanism,determine the factors affecting the motion reliability of the new 2SPR-2RPU parallel mechanism,establish the kinematics model of the new 2SPR-2RPU parallel mechanism,and determine the new 2SPR-2RPU parallel mechanism.Position inverse solution.Through the set trajectory combined with the new 2SPR-2RPU parallel mechanism position inverse solution,the improved fourth-order moment method is used to evaluate the reliability of the new 2SPR-2RPU parallel mechanism.(4)The reliability of the series six-axis welding robot and the new redundant drive 2SPR-2RPU parallel mechanism are solved by Monte Carlo method and fourth-order moment method respectively.The correctness and accuracy of the improved fourth-order moment method are verified by comparison of three methods.