Study Of Deterministic And Robustness Optimization For Automobile Steering Trapezium Mechanism

With the continuous improvement of automobile production technique,the performance of its steering system has already been greatly improved,however,there still exists some problems,which results in the recall of faulty cars.So how to further improve the quality of steering system is one of the main challenges faced by vehicle manufactures.As the important part of the steering system,steering trapezium mechanism determines its transmission performance,directly affecting the ride comfort and the tires' life.Therefore,there is still some need to do further study for the steering trapezium mechanism.At present,the research on the kinematic analysis and optimization design of steering trapezium mechanism has made great progress.The current kinematic analysis is generally aimed at a particular arrangement of the mechanism,short of the unified analysis for different arrangement.Meanwhile,it is lack of research and summary to the optimal design objective function and weight function of the mechanism,the application of the robust optimization design in steering trapezoidal mechanism is still less,there is not a general procedure.To the integral steering trapezium mechanism and the rack and pinion steering trapezium mechanism for reference,the kinematic analysis of different layouts is studied.The objective function and weight function for the steering trapezium mechanism are analyzed and compared comprehensively.Based on the Excel and Isight co-simulation,the deterministic optimization design for two typical steering trapezium mechanism is carried out;The Taguchi method and six sigma robustness optimization method are analyzed and summarized.Based on Excel and Isight co-simulation,the robust optimization design of two typical steering trapezium mechanisms is completed,and the robustness of different optimization design results are compared and analyzed.The main work is as follows:(1)Kinematic Analysis for the steering trapezium mechanism.Under the condition of basic assumptions,the integral steering trapezium mechanism is simplified as a planar four-bar linkage,and the rack and pinion steering trapezium mechanism as a crank-slider mechanism.with the closed polygon and vector analytic method,the kinematics of the different steering trapezium mechanism are analyzed.The relationship between the left and right steering wheels of the steering trapezium mechanism is deduced,which lays the foundation for the optimal design of the subsequent steering trapezium mechanism.(2)Study on the deterministic optimization of steering trapezium mechanism.The objective function and the weight function of the trapezium mechanism are studied and summarized.The optimization method of the two typical steering trapezium mechanisms based on Excel and Isight co-simulation is proposed,the deterministic optimization design model of the two typical steering trapezium mechanisms is established.The results of different objective functions and different weight functions are compared,and the best combination of objective function and weight function are determined.(3)Study on the Robustness optimization of the steering trapezium mechanism.The basic principles of the two robust optimization methods and Monte Carlo method are analyzed and the detailed procedures are established.As for Taguchi method,the orthogonal tables of the controllable factor and the noise factor are established,according to the signal-to-noise ratio(S/N),the best scheme is determined.As for the six sigma robustness optimization method,the distribution of design variables and random variables for two typical steering trapezium mechanisms are determined,and the robustness optimization design is carried out.Monte Carlo method is used to analyze the robustness of the steering trapezium mechanism after the deterministic optimization design and the robustness optimization design.