Research On Anti-rollover Fuzzy Control System Integrated Differential Braking With Active Air Suspension For Bus Based On ADAMS

While promoting the development of human society, automobiles are also making negative effects on modern society, among which the traffic accident was concerned a major cause. Traffic accidents have become "the most terrible damage to the world". Bus safety is the most important aspect in the traffic safety work as buses are the major form of vehicle on the highway. The damages in rollover accidents are only next to those in front impact accidents. Specifically, mass casualty is likely to occur in bus rollover accidents, for buses are vehicles with a large number of passengers and large centroid height and mass. Therefore, studies on bus rollover are of great value for the purposes of promoting the bus drive performance and decreasing live and property losses.A Chinese bus model equipped with air suspension system was selected as the objective in this thesis. According to the topological structure and dimension of actual vehicle, subystems of the bus simulation model, including front suspension, rear suspension, steering, tire, engine and body, were established with ADAMS/CAR and assembled as a whole. With the integrated system, basis for further researches were founded.Rollover accidents can be categorized into tripped rollover and non-tripped rollover. In this thesis, the scenario was set as follows:A bus tripped rollover accident occurred while the bus took a sharp turn on a low adhesion road, lost its yaw stability and started sliding, then hit an obstacle on the road. A 2-DOF ideal model was built and analyzed with based on vehicle yaw dynamics. Vehicle driving conditions was identified based on the whole-bus model and the differences of yaw-rate simulated with the 2-DOF ideal model. Utilizing the differential braking dynamics, yaw stability fuzzy PID control with yaw-rate as the control variable was established with MATLAB/SIMULINK to correct the unstable bus driving conditions. Simulation results showed:Yaw control system could effectively promote the driving performance on low adhesion coefficient roads and minimize the probability of tripped rollover accidents.For the scenario of tripped rollover resulted from body over tilting caused by high speed sharp turn on high adhesion coefficient roads, a 3-DOF tilt dynamic model and half-vehicle suspension dynamics was built and analyzed. Simulation was carried out with tilt stability control system based on differential-braking and active suspension control systems, and the results showed that the tilt stability control system could effectively promote the bus’s anti-rollover ability, while affecting the trajectory traction performances to a degree.Based on the control rule of anti-rollover control as the major and the trajectory traction control as the assistant, yaw stability control and tilt stability control were integrated to build the anti-rollover control system. Simulation results showed that the anti-rollover integrated stability control system could effectively suppress the sliding on low adhesion coefficient roads, therefore enhancing the driving performance; on high adhesion coefficient roads, it could significantly improve the anti-rollover ability while performing good traction of intended trajectory.