Design Of Distributed Electric Drive Vehicle Motion Control System

Recently,with the social and scientific development,people's demand for environmental protection,energy saving,power and safety of vehicle has gradually increased.As an important form of future electric vehicle development,distributed drive electric vehicle not only has environmental protection and energy saving characteristics just like the traditional electric vehicle but also improve the power performance and active safety of the vehicle with the advantage of the unique driving form.The research work of this paper mainly includes four parts,vehicle dynamics modeling,design of the vehicle state parameter observer,design of the vehicle linear driving controller,design of the vehicle steering controller.First,vehicle dynamics model of the distributed drive electric vehicle is obtained basing upon the method of hierarchical modeling.It is mainly composed of the following parts: the driver model,the steering system model,the motor model,the electric wheel model,the tire model and the body dynamics model.Due to the same experimental conditions in Carsim and Matlab/Simulink,the accuracy of the vehicle model is verified by comparison.Second,the adaptive linear tire lateral force model is set up based on unscented Kalman filter(UKF).Estimation method of vehicle lateral characteristics based on the offline parameter matching and online identification of the real-time readjustment variable about tire cornering stiffness increases the adaptive capacity of the system under the abrupt state change.The co-simulation of Carsim and Matlab/Simulink shows that the whole estimation algorithm realizes the accurate estimation of vehicle state parameters,and provides an accurate parameter basis for vehicle motion controller development.Then,the vehicle linear driving controller is established.According to the online identification of the optimal slip rate for each driving tire,the tracking of optimal slip rate control algorithm is set up by the sliding mode variable structure control.The co-simulation of Carsim and Matlab/Simulink shows that the vehicle linear driving controller make the motion of the tire near the optimal slip rate and make full use of the adhesion ability.The power of the vehicle is improved and the superfluous abrasion of the tire is reduced too.At last,the vehicle steering controller of the distributed drive electric vehicle is given basing on the method of hierarchical modeling.The controller consists of 2 parts,motion control section and moment distribution section.Considering the comprehensive influence of the side angle and the yaw rate,the motion control section put up a calculation method of the target direct yaw moment based on the linear quadratic optimal controller.In consideration of the stability distribution with the minimum tire load rate and the energy optimal distribution with the motor drive efficiency,the two distribution modes are coupled together through a reasonable weight coefficient to realize the comprehensive improvement of motion control performance.