Research On Optimal Design Of Electro-Hydraulic Active Steering System In Intelligent Transportation Environment

The electro-hydraulc active steering system with variable transmission ratio function can well solve the contradiction between low-speed flexibility and high-speed stability of automobiles.Due to the use of electro-hydraulic power assistance,the economy of the steering system is improved,and the steering assistance is adjustable.Therefore,the electro-hydraulc active steering system can satisfy the steering demand of greater power while taking into account the driver’s operating experience.However,the structure of the steering system is relatively complex,involving multiple coupled disciplines such as mechanical,electrical and hydraulic,which leads to greater challenges in its optimization design.In order to improve the comprehensive performance of the steering system,this paper focuses on the research of multi-objective and multi-disciplinary optimization design of the electro-hydraulic active steering system.The main research contents and innovations of this article are as follows:(1)The dynamic model of the electro-hydraulic active steering system and vehicle model are established.On this basis,the simulation model of the mechanical,electrical and hydraulic subsystems of the steering system is built based on AMESim software,and the energy flow of the steering system is analyzed.The quantitative formula of the evaluation index of the electro-hydraulic active steering system is proposed and deduced,including the energy loss of the steering system,steering road feel,steering sensitivity and steering stability,etc.According to the parameter sensitivity analysis,the structural parameters that have a greater influence on the evaluation index are selected as design variables.Then,an improved multi-objective optimization algorithm(NSGA-III-FF)is proposed and applied to the optimization of the structural parameters of the steering system.(2)The dynamic model of the steering system is combined with its physical model,and the steering modal is introduced the steering system evaluation index system.Combining DOE method,surrogate model method and finite element calculation,the first-order frequency response surface model of the steering system is constructed.Based on the DCCO multidisciplinary optimization method,a multidisciplinary optimization model with steering energy loss,steering road feel and steering sensitivity as the optimization objectives,and steering stability and steering modal as constraints is established considering the coupling relationship between the evaluation index.Then,the structural parameters of the steering system is optimized.(3)Based on the proposed DCATC multi-disciplinary optimization method,a multi-level optimization model with steering energy loss,steering feel and ride comfort as the optimization goals,and steering sensitivity,steering stability and steering mode as constraints is established considering the influence of suspension parameters on the steering system.Then,the structural parameters of the steering system are optimized,which further broadens the scope of optimization of the steering system performance.On this basis,the intelligent traffic environment is used as the setting scene,and the control parameters are optimized under variable working conditions,so as to improve the adaptability of the steering system under changing driving demands.(4)In order to verify the steering performance of the optimized system,a test bench for the electro-hydraulic active steering system was built and the bench test was carried out.On this basis,the hardware-in-the-loop test of the steering system under the intelligent transportation environment was carried out.The real traffic scenes are reconstructed in the virtual environment,and through real-time optimization of control parameters,the adaptability of the steering system to complex scenarios and the improvement of steering economy are verified.The research results of this paper verify the feasibility and effectiveness of multi-objective and multi-disciplinary optimization of the electro-hydraulc active steering system.It improves the comprehensive performance of the steering system and provides theoretical foundation and technical support for the optimal design of the electro-hydraulc active steering system.