Dynamic Stability of a Driver-Vehicle Rollover System with Time Delay

Vehicle rollover, as a fatal accident, has been an important and necessary problem to be solved in vehicle active safety research area. The published researches mainly focused on vehicle modeling, rollover stability analysis, and anti-roll control method, especially on integrated chassis control strategy. However, as a dominant factor in vehicle rollover accident, driver's operation has not been touched on in current publications. In order to explore the mechanism of vehicle rollover caused by driver's operation, an extended model of a driver-vehicle closed-loop system, with the time delay of driver's operation taken into consideration, is established in this paper. From the model, some dynamic characteristics of the driver-vehicle closed-loop system are discussed, including the dynamic stability of the system without time delay using the Routh-Hurwitz criterion, the delay-independent stability of the system based on the generalized Sturm criterion, and the critical time delay when the delay-independent stability condition does not hold. Then the influences of driver's operation on vehicle rollover stability are simulated in extreme driving conditions by numerical cases for a Sport UtilityVehicle (SUV). In addition, the stability regions of vehicle rollover are shown with respect to the parameters of driver's operation, such as the gain, the reaction time and the time delay. The results of simulation show that the time delay is the most important parameter of driver's operation to stability of vehicle rollover, and the gain of driver's operation has different influence on stability of vehicle rollover with different time delay.