Collaborative robot nonlinear stiffness modeling method

Abstract

The invention relates to the field of collaborative robots, in particular to a nonlinear stiffness modeling method for a collaborative robot, which comprises the following steps: step 1, robot module comprehensive stiffness modeling: splitting a robot into a plurality of modules, obtaining a structural stiffness matrix of each module, and then carrying out nonlinear modeling on a robot transmission system, the overall comprehensive rigidity of the robot is the sum of the comprehensive rigidity of all the modules, a connecting rod module comprehensive rigidity matrix is a structural rigidity matrix, and a joint module rigidity matrix is synthesized by the structural rigidity matrix and the nonlinear rigidity of the robot transmission system; step 2, robot static balance modeling: flexible deformation of each module is represented by adding virtual joints, and a robot static balance model under load and self-weight conditions is established; and step 3, robot nonlinear stiffness modeling. According to the method, finite element and virtual joint stiffness modeling methods are combined, and the overall stiffness and positioning precision of the robot can be improved.

Description

technical field [0001] The invention relates to the field of collaborative robots, in particular to a nonlinear stiffness modeling method of a collaborative robot. Background technique [0002] Collaborative robots refer to robots that can cooperate with humans to produce in a collaborative area. Due to their advantages such as high flexibility, light weight, high load-to-weight ratio, and high safety, they have become a hot research topic at present. The advantages of light weight and high load-to-weight ratio of collaborative robots can adapt to flexible and changeable tasks, and are easy to move and integrate, reducing redeployment costs, but at the same time it also brings difficulties to improve the rigidity and positioning accuracy of the robot. Under the constraints of high load-to-weight ratio, light weight, and safety, collaborative robots cannot improve the system stiffness of the robot by selecting high-strength materials, increasing the size of structural parts, ...

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Problems solved by technology

This method has the advantages of intuition, reliability, and high precision, but the disadvantage is that the modeling workload is large, and the calculation results of each modeling are only valid for the calculated pose and load. modeling calculation

[0005] 2. Matrix Structural Analysis (MSA), this method combines the finite element method, and the structural parts of the robot are equivalent to 3D flexible beams, and the analytical stiffness model of each part is established through material mechanics, and the overall structure is obtained through the kinematic relationship of each part. The stiffness model of the machine, but this method also reduces the accuracy while reducing the amount of calculation

[0006] 3. Virtual Joint Method (Virtual Joint Method, VJM), this method is the most commonly used modeling method for traditional industrial robots at present. Its main idea is to add virtual joints to the rigid model of the robot to describe the elastic deformation of connecting rods and joints. , this method balances the accuracy and calculation amount, and is easy to identify the parameters later, but this method cannot fully consider the flexibility of each part of the robot

At present, based on the assumption of small deformation, the existing robot linear stiffness model method can comprehensively consider the stiffness of each part of the robot and the impact on the stiffness of the robot, but there are few studies on the influence of nonlinear factors on the stiffness of the robot. The influence of load and static balance on the nonlinear stiffness of the whole machine is studied, but the influence of self-weight and stiffness nonlinear transmission elements on the nonlinear stiffness of the collaborative robot has not been studied

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