Research On Rollover Stability And Anti-Roll Control For Passenger Car

The property of passenger car rollover increases because of the great mass and high center of gravity. So, the rollover of passenger car becomes to be a hot issue in the area of vehicle active safety.In this paper, different models are built based on the characteristics of different passenger car. Then the rollover index is proposed to valuate the dangerous of passenger car. Also, the influences of main parameters on performance of rollover are simulated. Several control strategies are studied to prevent the rollover of passenger car. Furthermore, to verify the models and controller, a number of experiments are carried out using Carsim and Trucksim software with Electro Hydraulic Brake(EHB)system. The main contents are as follows.(1) The dynamic models of the passenger car rollover are built and verified. A six degree of freedom model is established to describe the rollover dynamics of passenger car and verified using Carsim software. And two different models are proposed to analyze the performance of bus rollover,including the rigid frame and the flexible frame respectively. Then, some steady state characteristic parameters and transient characteristic parameters are estimated using steady state characteristic value method and genetic algorithm. The models of buses are verified using Trucksim software.(2) New rollover indexes are proposed for the passenger car and bus, that can valuating the dangerous for tripped rollover and untripped rollover vehicles. To study on the rollover of passenger car due to the road input, a new rollover index is deduced and verified using Carsim software.Compared with the traditional rollover index, the result shows the new rollover index perform better in valuating the dangerous of the untripped rollover and the tripped rollover cased by road input. Also,the new rollover index is simplified to analyze the rollover dynamics of bus and verified using Trucksim software. Some numerical simulations are carried out on the main parameters which affect the performance of passenger car rollover. Then, some laws of the parameters’ influence on rollover performance are concluded, which can provide theoretical basis for passenger car designing.(3) Several control strategies are studied to prevent the rollover of passenger car. ProportionIntegral-Derivative(PID) controller and robust controller based on Genetic Algorithm(GA) are designed for the passenger car. The condition adaptability, anti-interference stability and parameter perturbation robustness of the two controllers are analyzed respectively. The results show that robust controller based on GA has better performance than PID controller. Also, the game H2/H∞ strategy are studied for the bus, and the results show that it works better in preventing bus rollover than other two methods. However, to meet the robust controller based on GA and game H2/H∞ methods’ requirement,the brake torque should be provide more quickly.(4) To verify the models and controller, numerous experiments are conducted using Carsim and Trucksim software with EHB system. To obtain an accurate model of EHB system, a test platform is developed and some unknown nonlinear parameters are estimated with the experiment results. Then,many experiments are carried out for passenger car using Carsim software with EHB system. The results show that the robust controller based on GA reduce the rollover index of tripped rollover obviously. Also, another experiments are conducted for bus rollover using Trucksim software with EHB system. The results show that the game H2/H∞ control strategy can prevent bus rollover effectively.