Optimal Design of Flexspline in New Modular Robotic Joints Considering Position Keeping Conditions

Abstract

In order to improve the service life of modular joints and meet the requirements of compact structure, considering the position keeping conditions of modular joints, a multi-objective optimization design method for the maximum stress and tube length of the new modular joint flexspline was proposed. This method established a finite element analysis model based on a new modular joint structure, conducted a thermo-mechanical coupling analysis on the joint under the holding state, and obtained the stress distribution of the flexible wheel. Plackett-Burman factorial design was used to screen the significant factors that affect the maximum stress. Based on the Box-Behnken test method and the least square method, the second-order response surface approximate model of the maximum stress of the flexspline was established. Taking the geometric structure parameters of the harmonic drive components as the design variables, and the maximum stress and tube length of the flexspline as the design goals, the response surface approximate model is optimized through the multi-objective genetic algorithm. The optimization calculation example of the new modular joint shows that the method can reduce the maximum stress of the flexspline while reducing the tube length, achieving the purpose of reducing the joint volume and increasing the service life.