Study On Longitudinal Stability Of In-wheel Motor Vehicle

Compared to the traditional internal combustion engine driven vehicle and centralized electric one, in-wheel motor driven electric vehicle has a simple structure, characteristics and advantages which are easy to manipulate and sensitive to response. In-wheel motor driven electric vehicle is characteristic direction of development of electric vehicles. Meanwhile, with the influence of the two major public issues, energy and environment, in-wheel motor driven electric vehicles are more rapidly developed. In this paper, the study object is in-wheel motor driven electric vehicles. The focus on work content launches its longitudinal driving stability.First, the paper analyzes the research status of in-wheel motor driven electric vehicles and stability control. According to the dynamics characteristics of in-wheel motor driven electric vehicles, on the basis of a reasonable simplification of vehicle,wheels, tires and motors, we establish a physical model of seven degrees of freedom, which contains the longitudinal motion, lateral motion, yaw motion, and four wheels turning motions.Secondly, the paper analyzes the factors, which affect the vehicle stability, including slip ratio, yaw rate and slip angle. We still focus on methods such as the logic threshold control and fuzzy control method, both of which are widely used in study.Again, the paper uses Matlab/Simulink to build in-wheel motor driven electric vehicle simulation model of seven DOF. The model is compliance with the vehicle dynamics physical model which can simulate simple travelling state after a certain simplification. Modules added to the model are based on threshold and fuzzy logic control methods.Finally, do some simulation analysis in the built in-wheel motor driven electric vehicle simulation platform. The simulations are from dynamics analysis on the vehicle to the stability control on the variety of centroid height, centroid distance to the front axis, the acceleration pedal input and vehicle load. Use the built model, we write the driving slip control strategy and analyse the different effects of kinds control methods designed before.