The Handlingstability Control Based On The Analysis Of The Instability Boundary Of The Vehicle

Speed, steering angle and acceleration is the critical input variable that infect the state response of the vehicle and manipulated directly by the driver. And they are injected by the related sensors in the electronic stability program. The input states’effect on vehicle stability is studied to offer the stability control a good basis.Firstly, from the dynamical and structural analysis of the coupling among the chassis subsystems, this article constructs physical models of vehicles based on actual vehicles. According to the physical model, its degree of freedom is determined, the system dynamical model is created by the use of the principle of Newton-Euler. Furthermore, in order to analyze dynamics stability and to study the steering stability control, the Dugoff tire model is introduced. In order to simulate the operating status of actual vehicle steering control, the best way of a pre-tracking driver model is to be introduced to construct a closed-loop control of the vehicle system,Then the dynamic model of the semi-vehicle is built, and Simulink model is built to have dynamic simulation to understand the effect of steering angle, speed and braking/tracking acceleration on the handling stability.the7-DOF vehicle model is built by simplifying vehicle dynamics model. How the steering angle, speed and acceleration affect the suspension is studied to understand that how they affect the handling stability.Then, according to the dynamic state of the wheel, the vehicle’s travel state is divided into linear region, the nonlinear region and outside the limits of adhesion area, according to the definition of the stability in control theory, the state is divided into vehicle stability region and non-steady areas. By using Dugoff tire model, linear and nonlinear boundary of the vehicle dynamic state is solved to determine the linear and non-linear area of the vehicle traveling area. Respectively, Routh stability criterion and the bifurcation theory are used for solving the stable region between steering angle and acceleration and the one between steering angle and vehicle speed.Finally, according to the analysis of driving state boundaries, respectively, the controller are designed on the conditions of braking steering and uniform steering. Under uniform conditions, according to the state response of vehicle, the layered coordinate controller is designed, whose coordinated control is achieved by distributing the weights that the lower controllers produce yaw moment,thereby the coordinated control is achieved. The controller of the active suspension is designed by LQG controller, the corresponding roll moment is produced to compensate for the taw moment by adjusting the active force of suspension. The sliding mode controller is adopted for the ESP, the yaw moment is achieved by the adjusting of sliding surface. And the control method is shown to be effective through the establishment of simulink model.