Research On Rollover Stability Based On Driver Manipulation And Suspension Control

In recent years,with the development of the automobile industry,the traffic accidents also increased.That rollover accidents are more likely to cause serious loss of life and property received more attention.The drivers' unreasonable manipulation of the vehicle is one of the reasons that cause the accidents,while the traditional rollover research method ignores the influence of the drivers' manipulation of the vehicle.So taking the drivers' manipulation into consideration and building “driver-vehicle” system are more in line with the actual situation.In this paper,we focus on vehicles with high center of mass.An eight degree of freedom vehicle model was established by using MATLAB/Simulink and the tire model was established based on magic formula.Then a comparison was conducted between the model we built and model of Carsim software with the same parameters of a SUV to verify the correctness and rationality of the model.After that,a driver model based on lateral acceleration feedback was built and its preview time was obtained by optimizing index.All that models constitutes “driver-vehicle” system.The rollover predict index is the foundation of rollover research.The LTR index and PLTR index were built with MATLAB/Simulink.By comparison the two index,PLTR has the following advantages than LTR in predicting the rollover accidents: it is more safe and can predict the rollover in advance than LTR.So,PLTR was chosen as the index in this paper.Vehicle rollover accidents are affected by many factors,such as the parameters of the vehicles,the vehicle speed,drivers' manipulation.Several factors' influence on the rollover index was discussed including roll stiffness,drive speed,driver's manipulation.The suggestion to avoiding rollover accident was given based on the results.Suspension system has a direct impact on the performance of vehicles,including ride,comfort,safety.By adjusting the suspension parameters,active and semi-active suspensions can generate additional control forces.Based on the simplification and assumption of the suspension system,the ideal additional control force was given in this paper.PID control is simple and widely used while Fuzzy control has a good control effect on the non-linear system.Fuzzy-PID Combine the advantage of the two theory and can get better control results.According to the characteristics of suspension system and Fuzzy-PID control,an anti-rollover controller was designed to control the rollover index of vehicles.The following simulation was chosen to verify the control algorithm: the fish hook simulation and double line change simulation.The both results show that the rollover index declined as well as roll angle and roll angle rate.Finally,the parameters of Fuzzy –PID were optimized by genetic algorithms.The rollover index and roll angle,roll angle rate further declined according to the simulation results.