Industrial robot reliability calculating method based on fourth-moment estimation

Abstract

The invention discloses an industrial robot reliability calculating method based on fourth-moment estimation. A D-H connecting-rod coordinate system of a robot is established and a forward kinematics equation is constructed, a joint space of the robot and a connecting-rod dimensional deviation are regarded as random variables, the distance between an actual position point and an expected position point is calculated and serves as a kinematic error of the robot, the kinematic error of the robot is regarded as a random variable and first four moments are calculated, a system performance function representing the kinematics reliability of the robot is established and first four moments of the performance function are calculated, a probability density function of the system performance function is solved by utilizing a fourth-moment estimation method, and integration is conducted to obtain the reliability of the robot. According to the industrial robot reliability calculating method based on fourth-moment estimation, probability distribution information of the joint space and the connecting-rod dimensional deviation is sufficiently utilized, so a few samples are only needed to complete the reliability calculation of the robot system, the time is obviously shortened and the efficiency is improved, and the industrial robot reliability calculating method is suitable for industrial robots which are connected in series and any other rotary joint types of industrial robots.

Description

technical field [0001] The invention relates to a method for calculating the reliability of a robot, in particular to a method for calculating the reliability of an industrial robot based on fourth-order moment estimation, and relates to series and parallel robots widely used in the fields of industrial production and pharmaceutical manufacturing. Background technique [0002] With the advent of the industry 4.0 era, in many fields such as processing, assembly and handling of large and complex parts, welding without fixture systems, spraying and engraving, etc., there are more and more requirements for the motion accuracy, stability and reliability of robots. However, due to the inevitable wear and deformation of the robot in the design, parts processing, assembly and use, there are inevitable errors in the robot body, mainly including the joint clearance at the rotating joint and the deviation of the connecting rod size. The deviation of the size of the connecting rod reduc...

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Problems solved by technology

[0002] With the advent of the industry 4.0 era, in many fields such as processing, assembly and handling of large and complex parts, welding without fixture systems, spraying and engraving, etc., there are more and more requirements for the motion accuracy, stability and reliability of robots. However, due to the inevitable wear and deformation of the robot in the design, parts processing, assembly and use, there are inevitable errors in the robot body, mainly including the joint clearance at the rotating joint and the deviation of the connecting rod size. The deviation of the size of the connecting rod reduces the motion accuracy of the robot's end. The existence of joint clearance not only affects the motion accuracy, but also causes joint impact, aggravates the vibration and even causes the robot's motion to fail. Therefore, the robot's motion under the influence of the above uncertainties Reliability research is of great significance

In the current industrial production, the methods used to calculate the reliability of robots mainly include the first-order reliability analysis method, Monte Carlo stochastic simulation method, especially the Monte Carlo stochastic simulation method is widely used, but due to the Carlo simulation needs to be based on a very large sample value to estimate the reliability of the system more accurately. In practice, not only is the cost high, but the efficiency is also low. Although the first-order reliability method can reduce the number of simulated samples, but Due to its limited calculation accuracy, it is mainly used in some mechanical systems with simple structure and low degree of nonlinearity, which cannot meet the requirements of fields such as aerospace and robot motion control systems.

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