Analysis of the vehicle driving stability region based on the bifurcation of the driving torque and the steering angle

Abstract

Integrated control systems for vehicle-handling stability are usually based on the steering bifurcation mechanism. The best integrated control performance is obtained by coordinating different control methods. However, in vehicle steering and driving conditions, the coupling characteristics of the longitudinal forces and the lateral forces of the tyres must lead to changes in the bifurcation characteristics. The corresponding vehicle dynamics stability region has to be redetermined. The corresponding integrated control method also needs to be adjusted. Therefore, in combination with the physical significance of the dynamics equilibrium point of the vehicle system, the definition of the driving stability region of the vehicle based on the characteristics of the driving torque and the steering angle bifurcation is proposed. With the concept presented above, the five-degree-of-freedom non-linear vehicle system model for the driving stability region of the vehicle was solved. The simulation results show that, according to the driving stability region of the vehicle, the vehicle dynamics stability with different driving torque inputs and different front-wheel steering-angle inputs can be accurately estimated. The study of the driving stability region of the vehicle is beneficial for engineering applications in non-linear automotive dynamics research. In addition, it provides the theoretical basis for integrated control of the vehicle-handling stability.

Active Steering and Driving/Braking Coupled Control Based on Flatness Theory and a Novel Reference Calculation Method

“…Based on the nonlinear 3DOF vehicle model and magic-formula tire model [26], by solving the equilibrium points under a certain speed, it is found that the lateral velocity and yaw rate are approximately proportional relation in the steady branch. The steady state is reference state in stability control, so the vehicle reference lateral velocity can be expressed by the equation:…”

Numerical continuation applied to internal combustion engine models

“…The approach has also been used in current literature directly related to the automotive industry, in areas such as vehicle dynamics, wheel and suspension dynamics, permanent synchronous motors and braking systems. A bifurcation analysis helped determine how driving speed and steering angle 12 and torque and steering angle 13 affect the stability in a cornering vehicle. In addition, the lateral dynamics of a vehicle driving straight ahead was also studied.…”

Limit cycles at oversteer vehicle

“…Stability maps with steering angle and the drive torque as bifurcation parameters have been presented in [6] before. In contrast to this study, equilibrium points of an understeer vehicle (without Hopf bifurcation) were considered for continuation, while supercritical Hopf bifurcations have been pointed out for different characteristics of oversteer vehicles in [7].…”

“…Next to [6], longitudinal slip and respective longitudinal vehicle dynamics have been included in [12,13], resulting in smaller areas of attraction to a stable equilibrium point. As a further extension to bifurcation analysis of equilibrium points, a method to use bifurcation and continuation procedures also for evaluation of vehicle stability during acceleration and braking has been proposed in [14].…”