Multi-Objective Robust Optimization Design Of Micro-Motion Platform Considering Double Uncertainties

With the development of science and technology,micro-motion platform has been widely used in many frontier fields such as biological engineering,medical science,ultra-precision machining and aerospace.The stability of its performance determines the working quality of the platform,so it is of great significance to carry out robust optimization design of micro-motion platform.However,the current robust optimization design of the fretting platform based on the proxy model only considers the fluctuation of the design variables,equates the proxy model with the real model,and ignores the model uncertainty caused by the prediction error.If the model uncertainty is ignored,it will inevitably bring additional errors to the design,which may lead to the failure of the optimal solution.In order to solve the above problems,this paper takes the composite bridge fretting platform as the research object.On the basis of comprehensive consideration of the double uncertainties of design variables and proxy model,the multi-objective robust optimization design of the fretting platform is carried out.The main research work is as follows:(1)In order to ensure the accuracy and validity of the data used in the multi-objective performance optimization of the micro-motion platform,the static and dynamic theoretical modeling of the performance indexes of the composite bridge micro-motion platform in terms of amplification,intrinsic frequency and maximum stress is carried out according to the pseudo-rigid body method and Lagrange’s equation,and the theoretical model is verified by finite element simulation.The validity of the data used in the optimization process is ensured by the mutual corroboration of theory and simulation.(2)In view of the large number of structural design variables of the micro-motion platform,it is difficult to intuitively determine the design variables that have a great impact on the performance of the platform.Based on the orthogonal experimental design,the sensitivity analysis of the structural design variables of the micro-platform was carried out to study the influence of each design variable on different performance indicators.Then,the calculation method of structural comprehensive contribution coefficient based on entropy weight TOPSIS method is proposed,and the key structural design variables which have great influence on multiple performance indexes of the micro-motion platform are screened out based on this method.(3)In view of the complex nonlinear relationship between the performance response of the micro-motion platform and the design variables,as well as the complicated process of traditional theoretical modeling,based on the five key structural design variables selected,50 groups of sample points were obtained through the optimal Latin hypercube design.A Kriging proxy model reflecting the response relationship between design variables and performance indexes of the micro-motion platform was constructed.In addition,10 groups of sample points were used to test the accuracy of the model,which verified the reliability of the constructed model and laid a foundation for the robust optimization of the micro-motion platform.(4)To address the problem that the traditional robust optimization design of the micro-motion platform only considers the design variable uncertainty,a multi-objective robust optimization method for the micro-motion platform that considers both the design variable uncertainty and the agent model uncertainty is proposed.Based on the constructed Kriging model,the conventional robust optimization model and the robust optimization model considering the dual uncertainty are constructed respectively,and then the NSGA-Ⅱ algorithm is used to obtain the robust optimization solutions under different methods.