| The number of motor vehicles in China is large,and the road safety situation is complicated.Motor vehicle traffic accidents cause a large number of casualties and property losses every year.Statistics show that the vehicle rollover is a kind of high degree of danger in traffic accidents.With the rise of the Internet economy in recent years,China’s express transportation industry has also developed rapidly,and the volume of road freight transportation is huge.Due to its large loading quality and high center of mass,commercial vehicles are dangerous vehicles that are particularly prone to rollover.After comparing the anti-rollover control effects and characteristics of active suspension,active stabilizer bar,active steering and differential braking,a dual-axle commercial vehicle was controlled by anti-rollover control based on active steering and differential braking.An eight-degree-of-freedom rollover model including longitudinal motion,lateral motion,yaw motion,roll motion,and four wheel rotations,and a linear two-degree-of-freedom vehicle model including lateral motion and yaw motion are established.And considering the non-linearity of the tire,the magic formula tire model was established and fitted.Through theoretical derivation and simulation experiments,a integrated control strategy for active steering and differential braking in commercial vehicle anti-rollover control was developed.The hybrid characteristics of the control system are analyzed,and a hybrid switching anti-rollover control system is established based on the hybrid automaton model.In the discrete dynamic part of the system,the operational rollover process is identified as high rollover risk mode,transition mode and no-control mode.In the continuous dynamic part of the system,the high-rollover risk mode is controlled by the differential braking fuzzy logic with the desired lateral load transfer rate as the target;the transition mode is controlled by the active steering fuzzy logic with the desired yaw rate.Based on the driver model in Truck Sim,the Truck Sim and MATLAB / simulink co-simulation was carried out under the condition of double line change andserpentine winding pile with different initial speeds.The results show that after hybrid anti-rollover active control,the vehicle lateral load transfer rate and roll angle are significantly reduced.At the same time,the path tracking ability is also improved,and other dynamic parameters are also within a reasonable range.Compared with pure differential braking,the control method proposed in this thesis improves the path tracking ability while further improving the safety of rollover,effectively solving the contradiction between differential braking and active steering control objectives,and avoid the complicated coupling between active steering and differential braking.Finally,a HIL(Hardware-In-the-Loop)platform was established based on NI PXI and NI c RIO,and the HIL further proved the effectiveness and real-time performance of the control system in the actual controller. |
