Research On Vehicle Anti-Rollover Control Based On Active Steering And Differential Braking

With the rapid development of the vehicle industry and the enhancement of the road condition, the vehicle speed has become higher and higher. Meanwhile, more and more traffic accidents occur after the number of automobiles increasing fast. Because of the loss of lives and property grows heavier caused by the traffic accidents, the vehicle security, especially the lateral security, has wined more and more attention. The Active Safety Technology and the Passive Safety Technology have become focus of the vehicle security research. Due to the serious harm of rollover, more and more researcher and auto manufacturers have been doing much research on the theory of rollover and the anti-rollover control methods. But in China, the research on this field is just in the initial stage. So, Studying on the anti-rollover control to enhance the vehicle security has practical significance and broad application prospects.For a tire, its lateral force and braking force are both related to its vertical load, and the vertical load is affected by the roll movement, moreover the Lateral-load Transfer Rate (LTR) is an important parameter to describe the change of the vertical load. By considering this, a nonlinear tire model and an 8-DOF vehicle dynamic model have been built based on the LTR, and the study on anti-rollover control is base on these models.Active steering theology can change the steering angle independently to change the movement of the automobile. Through analysis how the steering angle influences the roll movement, this paper uses active steering theology as an anti-rollover control method. During the simulation, the method is validated. The results show that active steering theology can improve the anti-rollover performance by reducing the LTR through change the yaw rate and the lateral acceleration.Differential braking technology can change the vehicle dynamic to improve the driving movement. After analyzing the differential braking effect on the dynamic and its fundamental for anti-rollover control, a special dynamic model has been built based on the LTR, and then, simulation has been done. Through compare the effect of differential braking and the common braking, differential braking was proved better. Furthermore, how the braking force yielded by differential braking do effect on the driving movement was discussed. All of these study provide theory for the anti-rollover controller design. Finally, based on the analysis above, a sliding mode control theory and its controller design method for anti-rollover by integrated active steering and differential braking was presented. During the simulation, the method works. The results show that this control method can not only enhance the anti-rollover ability but also keep the car driving on the right way.