Research On Control Algorithm Of Bus Anti-Rollover Based On Electronic Braking System

Along with China’s rising economic power, the emphasis on infrastructure has intensified. As motorway networks maturing and bus performance rising, more and more citizens choose buses as means of travel. Meanwhile, the number of casualties caused by vehicle accidents increased year by year.Due to the restrictions of the functional requirements of buses, it is difficult in design to avoid a high center of mass and a relatively large aspect ratio. In addition to the large capacity, it is more likely for accidents to happen, especially in rollover accidents. This will ultimately harm the general public life and property safety. Therefore it is essential to design specific anti-rollover control algorithm targeted for buses. It is shown that, monitor of operating data and driver’s intended actions in real-time, prediction on the possibility of rollover and active intervention on brake system by applying differential braking can effectively reduce the possibility of bus rollover.This paper topics from the National Natural Science Foundation "based on the heavy-duty semi-trailer model predicts the kinetic stability of multi-objective control study" (Project No.51075176) and Jilin Province Science Foundation "the development and matching of heavy-duty vehicle electronically controlled pneumatic brake system" (Project No.20150204066GX)Firstly, a dynamic model was built for a bus in order to accurately simulate the study object. Then on the basis of comparative study and analysis of current researched both domestic and foreign, bus rollover control strategy based on dynamic lateral load transfer rate threshold was proposed. To characterize the steady state vehicle operating data,3-DOF model of the bus was built and verified. Finally, referring to foreign advanced technology and domestic current development trends in bus braking technique, electronic braking system was chosen as a hardware test platform. A bench for bus electronic braking system was built and the control algorithm was verified in hardware-in-loop experiments.The main work is as follows:Dynamic modeling for the bus in this study was built. To investigate the handling factors that will affect bus rollover stability, double lane change and fishhook maneuver were simulated in TruckSim. Analysis showed that the factors are vehicle speed and steering wheel angle. The critical vehicle speed and maximum steering wheel angle when rollover occurs in buses without active control were calculated through strict control-variables simulations.Obtaining the steady state vehicle operating data,3-DOF vehicle reference model was built in Matlab/Simulink and was verified by comparison to steady state vehicle experimental curves generated in TruckSim. To further improve model accuracy, the parameter of rolling stiffness for steady state vehicle under different speed and steering angle was identified using TruckSim.For bus rollover control objectives, anti-rollover control strategy based on dynamic lateral load transfer rate was proposed. On the basis of the early simulation results, bus anti-rollover control strategy based on dynamic LTR threshold under different speeds and steering wheel angle was designed. According to the idea of differential braking, the control strategy would solve the torque compensation to maintain vehicle stability using the difference between the actual and theoretical vehicle operating data, combined with PID control algorithm. Compensation torque was established by applying different braking force on wheels in order to prevent excessive roll angle that might lead to rollover caused by factors such as pilot error or road condition changes. To verify the effectiveness of control programs, TruckSim-Simulink co-simulation of common bus rollover conditions were simulated. Experimental results show that the control program can effectively prevent the occurrence of rollover accidents.To further verify the control strategy performance in practical application, anti-rollover control strategies HIL experiments were conducted. Experimental results showed that in the presence of noise, air pressure hysteresis and other unfavorable factors, the control strategy was still able to ensure bus roll stability.