Multi-objective Optimization Design Of Reliability Of The Main Structure Of Laster Cutting Machine Tool Considering Uncertainty

The influence of the uncertainty factors exists in the design,manufacture and the process of using of the parallel mechanism,in the deterministic multi-objective optimization of the parallel mechanism ignoring uncertainty,the uncertainty factors of the parallel mechanism is spread and accumulate between the multiple objective function and ultimately,Which ultimately caused the fluctuate of demand performance and affect the reliability of the performance requirements of parallel mechanism.Therefore,in order to ensure the accuracy and reliability requirements of the parallel mechanism,it is necessary to introduced the reliability optimum design of considering uncertain factors into the multi-objective optimization design of parallel mechanisms.this paper adopt parallel mechanism as the laser cutting machine body,introduced the reliability optimum design of considering uncertain factors into the multi-objective optimization design of laser cutting machine tool body,improving the precision and reliabilityof laser cutting machine tool body.The main contents are as following:(1)In order to combined the advantages the parallel mechanism with the development trend of high speed,precision and cutting plate of the laser cutting machine,adopt upright 3-PUU parallel mechanism as the laser cutting machine body.Analyzed the kinematics and dynamics laws of the 3-PUU parallel mechanism,including the motion characteristic analysis based on the reciprocal spiral theory.The geometric constraint equation is used to obtain the Positions solution equations of the mechanism.Adopt 3D fast polar coordinate searching method get the workspace.The Jacobian matrix and the Hessian matrix of the parallel mechanism are obtained by imaginary mechanism method.Analyzed the kinematics of the parallel mechanism based on the influence coefficient matrix.Analyzed the inverse dynamics of the parallel mechanism by the Newton-Euler method.(2)In order to ensured the correctness of kinematics and dynamics theory,we use the means of united simulation of Matlab numerical calculation and Adams 3D modeling.The consistent of the curve obtained by two kinds of simulation,ensured the correctness of kinematics and dynamics theory and the reliability of the simulation results,Validated the applicability of the parallel mechanism used for laser cutting machine tool body,Which provides the correct theoretical basis for the establishment of performance indicators.(3)In order to improve the overall performance of parallel mechanism,research on multi-objective optimization of parallel organization.According to the service environment and performance requirements,constructed the multi-objective optimization mathematical model is constructed according to the service environment and performance requirements such as the workspace,the global performance of the speed,acceleration and the inertial force.Searched Pareto solution from the design space used the second-generation non-inferior sort genetic algorithm(NSGA-II)based on Isight.The optimal Pareto solution is selected in the feasibility design point,which makes the parallel mechanism achieved the best overall performance.(4)In order to ensure the reliability requirements of the parallel mechanism,managed the stochastic uncertainties in the parallel mechanism by the way of 6 Sigma reliability optimization based on Isight.The method of probability theory is used to analyze the uncertainty of random parameters and random noise,and a multi-objective reliability optimization model is established.On the basis of multi-objective optimization results,the optimization of uncertainties is considered based on Isight.By comparing the reliability of the optimization results,we can arrived at the multi-objective reliability optimization considering uncertainty is more reliable and more close to engineering practice.This topic research can not only promote the development of laser processing technology,but also make up the shortage of ignoring the uncertainty factors in traditional parallel mechanism optimization design,the optimization results is more close to the engineering practice.This research has a certain guiding significance to improving our design ability and design quality of parallel mechanism.