Rollover Stability And Anti-roll Control Of A Three-axle Bus

The three-axle bus is a kind of high-capacity single section bus.As the advantages of carrying more passengers and good comfort,it has become one of the most popular means of transport.Because of its large mass,high center of gravity and indeterminate mass distribution,the three-axle bus is easy to rollover.In this paper,the full vehicle rollover dynamics model of a three-axle bus is built.The rollover index is established based on the rollover dynamics model and the effects of main parameters on the rollover stability is researched.The anti-roll control strategy of three-axle bus is designed.Then the maneuver adaptability and robustness are analyzed by co-simulation of Trucksim and Matlab in several typical conditions.The main contents contributions are as follows.(1)The dynamic model of three-axle bus is established and verified.Considering the influence of unsprung mass on the rollover stability,a four degree of freedom rollover dynamic model is established.On this basis,a six degree of freedom rollover dynamic model is established considering the influence of roll coupling on the roll stability.The parameters such as mass,equivalent roll stiffness and equivalent roll damping of bus body are estimated through equivalent method,steady state characteristic method and genetic algorithm.The rollover dynamic model is verified by simulations in Trucksim.(2)The influence of the main parameters of the three-axle bus on the rollover stability is analyzed.Considering the roll coupling phenomenon of the three-axle bus,the rollover index of the three-axle bus is derived,and the correctness and effectiveness of the index is verified.The rollover stability of three-axle bus under different working conditions and external disturbance is analyzed,and the general rules between rollover stability and key parameters of three-axle bus,including structural parameters and travel parameters are obtained.These rules provide a theoretical basis for improving the ability of anti-roll and reducing the risk of rollover.(3)A multi-object MPC rollover control strategy for the three-axle bus is proposed.According to the rollover stability rules of three-axle bus,the yaw stability and the roll stability are chosen as the control targets.The multi-object control strategy based on active front steering is designed applying the theory of model predictive control.The maneuver adaptability,robustness against external interference and robustness of parameter perturbation are analyzed in the simulation of typical working conditions.These results show that with a small value of front wheel angle control output,the multi-object model predictive control(MPC)rollover control strategy can not only effectively reduce the rollover risk of the three-axle bus,but also restrain the understeer during the rollover control process.