Research On The Coordinated Control Of Rolling And Yaw Stability Of Commercial Vehicle With Pneumatic Braking System

With the development of China’s economy and the improvement of transportation infrastructure,commercial vehicle ownership has continued to increase.By the end of 2017,the number of commercial vehicles in China has exceeded 40 million,and it has played a key role in cargo transportation.Due to the heavy weight of commercial vehicles and the high position of the centroid,frequent traffic accidents are caused by vehicle instability.The electronic stability control system can be equipped to improve the stability of the vehicle.Commercial vehicles mostly use pneumatic braking systems.The existence of a certain hysteresis in the pneumatic braking system makes it difficult to implement the control system.At present,there is less research on this aspect in China.The research institutions are mainly concentrated in various universities.By now,there are no mature products.The main research purpose of this article is to develop a stability control system for pneumatic brake systems based on the research experience of our research group on stability control systems.The main work of this thesis includes studying the structure of the pneumatic brake system of commercial vehicles based on domestic research status,and understanding the basic structure and operating mechanism of the brake system and key components.Bought parts and components required for the pneumatic brake experimental bench.The experimental bench was built and the air pressure valve was tested.The actual pressure of the brake chamber in the hardware-in-the-loop experiment can be directly obtained by the pressure sensor,it is impossible to directly calculate the pressure of the brake chamber when the control algorithm is verified by offline simulation.Therefore,the model of the pneumatic brake system was established using AMESim.After the establishment,in order to verify the accuracy of the pressure estimation of the model,the pressure measured by the experimental bench sensor was compared with the pressure estimated by the model.After comparing the pressure images,the model can be used to accurately estimate the pressure of the brake chamber,and the estimated pressure is basically consistent with the actual chamber pressure.After analyzing the lateral load transfer rate and the zero-moment-point,the zero-moment-point was selected to evaluate the vehicle’s lateral stability.The value of the zero-momentpoint on the y-axis is calculated by the data measured by the sensor,and the lateral stability of the vehicle is judged and controlled by comparing with the threshold value.In terms of yaw stability,the sideslip angle and yaw rate was selected to demonstrate the stability.The difference between the ideal and actual yaw rate was used to determine whether the vehicle was currently understeer or oversteer.A fuzzy controller is established to calculate the additional yaw moment required when the vehicle is unstable,and the braking force required for the brake is derived.Finally,the pressure required for the brake air chamber is estimated and the brake air chamber is adjusted by adjusting valve.The value follows the signial sent from controller,and the wheel to be braked is determined according to the understeer or oversteer of the vehicle.At the same time,control of rollover is given priority,and yaw stability is controlled when there is no danger of rollover,so that the control can be coordinated to improve the driving stability.After the control strategy model and the brake system model are completed,the control strategy is initially verified through the joint simulation among Simulink,TruckSim,and AMESim.The brake system model is based on AMESim,the vehicle model is based on TruckSim,and the control strategy is based on Simulink.Using the TruckSim to set the two conditions of the open loop double lane change and the sinusoidal amplification to be tested to verify the control strategy,it can be seen from the simulation images that the stability of the vehicle has been significantly improved after the control.Finally,the control strategy was further verified through hardware-in-the-loop experiments.The hardware-in-the-loop experimental platform is include the pneumatic brake system experimental bench,the rapid prototype controller MicroAutobox,and the real-time simulation system Simulator.The control strategy was verified under two working conditions include open loop double lane change.The control strategy was further verified by analyzing the sideslip angle,yaw rate,and -? phase diagram.