A joint stiffness modeling method for industrial robots considering contact

Abstract

The invention discloses an industrial robot joint rigidity modeling method which considers contact, and belongs to the field of industrial robot dynamic characteristic analysis study. By extracting key contact structure characteristics of each industrial robot joint, contact structures are assumed to be spring structures with a certain torsional rigidity, and an equivalent system model of all thejoints is built. According to measurement data, based on a power spectrum density method, three-dimensional surface fractal parameters and surface roughness parameters are calculated. All the contactstructures are subjected to stress analysis, and all contact pressure values corresponding to different joint input torques of the contact structures are calculated. By building an equivalent torsional rigidity model of springs in parallel connection and by making all contact rigidity and a reducer rigidity connected in parallel, a joint equivalent torsional rigidity is calculated. Through the combination of a fractal theory and structural stress analysis, an industrial robot joint rigidity model is built, by considering a contact rigidity, a more accurate theoretical estimation joint rigidityis calculated, and a certain method basis is provided for dynamic error compensation analysis at the tail end of the robot.

Description

technical field [0001] The invention belongs to the field of analysis and research on the dynamic characteristics of industrial robots, and in particular relates to a joint stiffness modeling method of industrial robots considering contact. Background technique [0002] The joint stiffness of industrial robots is one of the key factors affecting the accuracy of the terminal operation, and the joint stiffness research is an important basis for the compensation control of the terminal operation error. Traditional industrial robot joints are mainly composed of motors, reducers, synchronous belts, gears and other parts, and there are various connection methods between the parts. Currently, joint stiffness analysis mainly includes three methods: experimental identification method, finite element analysis method (FEM), and theoretical modeling method. Among them, the experimental identification is divided into static load test method and dynamic load test method: static load test...

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Problems solved by technology

As a theoretical analysis method, the finite element analysis method can estimate the stiffness analysis of some parallel robots with simple joint structures, but its application is limited for the complex joint models and constraints of industrial robots

The theoretical modeling method is a method to characterize the joint stiffness with a mathematical model. At present, most scholars ignore the influence of contact and calculate the torsional stiffness of the joint by connecting the stiffness of each structure in parallel, which has a large analysis error.

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