Research on integrated optimization design method of electric vehicle chassis

Abstract

With the development of vehicle intelligence and electrification, the performance of vehicle chassis system is highly demanded. Most existing researches have adopted the structure parameters optimization design method for the partial chassis subsystem, which cannot improve global vehicle performance. In this paper, the chassis system of distributed drive electric vehicles is taken as the research object. The chassis system integration optimization design method is studied. Firstly, the dynamic vehicle model, which includes active suspension, electric power steering, and motor braking systems, is established. Secondly, according to the performance requirements of suspension, the riding comfort index is formulated. According to the requirements of steering performance, the indexes of steering road feel and steering sensitivity are derived. According to the performance requirements of the braking system, the braking feel index is formulated. Based on the subsystem indexes, the comprehensive performance evaluation index of “comfortable-stability” of electric vehicle chassis system is proposed for the first time. Aiming at the minimum of the weighted sum of each subsystem performance index, the optimization constraints of the suspension, steering, and braking systems are considered. In order to avoid the subjectivity of weight selection, the weight coefficient of the optimization target is determined by the weight method of CRITIC. Then the chassis system’s mathematical model of multi-objective optimization is established. Finally, based on the NSGA-II algorithm, the chassis system is optimized. And based on the simulation software, the comparative analysis is carried out. Simulation results indicate that compared with the unoptimized vehicle, the amplitude of FVA and RVA indexes of the optimized vehicle is reduced by 9.87% and 2.23%, the amplitude of steering road feel index is increased by 15.51%, and the amplitude of BF index is reduced by 20.13%. The comprehensive performance of the vehicle chassis has been improved.