Research On Commercial Vehicle Brake Failure Characteristics And Stability Control Under Special Conditions

With the rapid rise of the transportation industry,commercial vehicles,as an important means of transportation,have received increasing attention for the ir safety and stability.Vehicle braking failure is a more dangerous traffic accid ent.When the vehicle is driving in corners and growing downhill,the probabil ity of braking failure is greatly increased due to the frequent use of the brakin g system,and there is a huge hidden danger to traffic safety..So the researc h on the instability characteristics and stability control of commercial vehicles after braking failure is of great significance.According to the above conditions,this paper designs a stability control strategy when the brake fails,and condu cts Truck Sim-Simulink joint simulation and hardware-in-the-loop experiment ver ification.The main research is as follows:(1)In order to improve the braking performance and braking stability of vehicles,the thermal decay characteristics of the brake failures of commercial vehicle drum brakes,the thermal decay mechanism and the influencing factors of braking failures are analyzed,it points out that the effect of temperature on the brake materials is more obvious;the analyzing of dynamics of braking fai lure vehicles lays a theoretical basis for the analysis of the impact of vehicle braking failure stability.(2)In order to reduce the impact of vehicle braking failure on vehicle dri ving stability,the Truck Sim-Simulink joint simulation was used to compare bra king failure vehicles under different ground adhesion coefficient conditions;the simulation results show that any of the vehicle wheels braking dynamical par ameter cannot meet the national standards when-the brake fails,which seriousl y affects driving stability.(3)In order to improve the brake performance of the vehicle under long downhill and cornering conditions,based on the dynamic characteristics of the vehicle,a strategy is proposed to compensate brake force differentially when the brake fails with single wheel.Fuzzy PID controller for angular velocity des igned.The simulation results show that the braking distance and longitudinal a cceleration of the vehicle are effectively improved by 25% and 15%,respectiv ely,the maximum lateral acceleration and the maximum yaw rate are reduced by about 50%,which significantly improves the safety and stability of the sim ulated vehicle when the brake fails.It shows that fuzzy PID control strategy c an effectively improve the braking stability under commercial vehicle braking f ailure conditions.(4)Based on the above research,a hardware-in-the-loop verification experi ment is performed.The experimental results show that due to the actual hardw are in the loop hysteresis,but the control effect is still within the effective ran ge,the braking distance is reduced by 18%,and the longitudinal acceleration i s increased by 20%,The yaw acceleration and lateral acceleration are improv ed by 45%,which effectively improves the safety and stability of hardware-inthe-loop braking failures,and meets the national standards for driving brakes.