Research On Commercial Vehicle Brake-by-wire System And Its Application In AEB

The intelligent safety control of commercial vehicles in specific scenarios is expected to lead the application of intelligent vehicle technology,and the brake-bywire system is one of its core technologies.This article conducts an in-depth study on the pneumatic braking system of commercial vehicles.First,the pneumatic braking system is controlled by wire,and then the braking model of commercial vehicles is established.Based on the combination of the two,a compound control strategy combined with ABS pneumatic braking and regenerative braking were proposed,and an improved AEB strategy was designed.Then the control strategy was simulated and verified on a co-simulation platform with typical operating conditions,and finally a variety of operating conditions were performed on the hardware-in-the-loop experiment platform.The specific work content is as follows:Firstly,for two-axle commercial vehicles,the overall vehicle model,single-wheel model and single-vehicle model were established,and the relationship between various physical quantities was established,and the relationship between slip rate and road adhesion was studied,which is the foundation of ABS control strategy.After analyzed the single-vehicle model,a state estimation algorithm for vehicle mass and road grade combined by the extended Kalman filter method and the forgetting factor recursive least square method is proposed.Then an improved TTC model is established on the basis of the traditional AEB control strategy,and then the control strategy of the brake-by-wire system as the executive mechanism of the AEB strategy is introduced.Aiming at the emergency braking conditions,an ABS pneumatic braking control strategy based on the logic threshold method is proposed,which basically meets the braking requirements of a variety of roads.A sliding mode control braking strategy is proposed for conventional braking conditions.After the total braking force is obtained,the braking force distribution of the front and rear axles is carried out according to relevant regulations,and then the rear axle air pressure braking is carried out under the premise of ensuring braking safety.The distribution of dynamic and regenerative braking improves the efficiency of energy recovery.Then a joint simulation platform of Simulink and Truck Sim is established.On this platform,the ABS control strategy,quality and slope estimation algorithm and braking force control distribution strategy proposed in this paper are simulated and verified.Experiments show that the ABS control strategy proposed in this paper can improve the braking safety of the vehicle and shorten the emergency braking time;the accuracy of the quality estimation is higher,which is about 2% higher than the traditional EKF algorithm;the energy recycled during the braking process is significantly increased,up to 6% of the total battery.Finally,a pneumatic brake-by-wire system bench was built on the basis of the traditional pneumatic braking system,and then the ABS logic threshold method and the AEB control strategy were braked experimentally verified under typical operating conditions on this platform.The experiment showed that the ABS strategy this article proposed can actively brake on different roads,and the braking effect meets the basic requirements of general commercial vehicles.The AEB strategy can prevent the vehicle from colliding with obstacles when there are obstacles in front of the vehicle.