Research On Integration Control Of Electronic Stability Program And Semi-active Suspension For Light Vehicle

With the rapid development of automotive electronics technology and the chassis control technology improved,a large number of electronic products have been installed in the vehicles. Examples of active braking systems are Electronic Stability Program(ESP)and the Electro-Hydraulic Brake system (EHB); examples for suspentions are the Active Suspention(AS) and Semi-active Suspention, Continuous Damper Control(CDC), Active Roll Control(ARC). Steering systems are Electronic Power Steering(EPS), Active Front Steering(AFS) and Rear wheel Steering(RWS).However, in the development of these new systems, this is usually a concern which is achieved by the system itself corresponding control objectives and it will not be considered too much when they joined the vehicle control system , other subsystems maybe have the bad impact , for instance, the changes of the vertical load brought about by Active Roll Control (ARC) may not conducive for ESP controlwhich need sufficient ground adhesion .When large lateral acceleration movement has taken place, change of body roll through "the axis effect " to the accuracy of vehicles , so affect vehicle handling and stability. Therefore, people gradually began to pay attention to the integrated control concept of the chassis, and have been in-depth study of the subsystems in the kinematic control which there will be interference and mutual coupling.On the basis of the implementing agencies Sensor demand and reasonable sharing of information they creat a coordination mechanism between the various subsystems ,so their function does not interfere with the action and conflict, and can achieve optimal performance.As everyone knows, the suspension can direct impact on the smoothness of vehicles and body posture , by grounding tire load indirectly it also can affect manipulation and stability. Advanced semi-active suspension as a sort of suspension, by adjusting the damping or stiffness, on the one hand it can be a good inhibition to roll in the process of braking and pitch and improve comfort, on the other hand, it also can controll the vertical load transfer of the front and rear axis on the brake, as well as affect the re-distribution of the vertical load beween the left and the right wheels when steering, which will directly or indirectly affect the cornering characteristics of the tire and vehicle steering characteristics; ESP can maximize the use of the tire and road surface adhesion potential .the side angle and yaw rate can be controlled within the permit limits, through yaw torque compensation it guarantee that the vehicles have enough stability and manipulation of active safety. Therefore if we combine ESP and semi-active suspension in the design process ,it will not only better in vehicle handling stability and comfort, but it will also reduce the excessive participation of the ESP and the dynamic performance decline . But the two systems have a mutual constraints and a complex relationship between the coupling, and we can not simply stack function ,we should study in depth the mutual constraints and the interaction mechanism between them.The paper tells the theoretical analysis on how to control them better ,so they can make greater contributions to improve the overall performance of the vehicles.In all, the following researches have been finished.Firstly,The vehicle dynamic model are established, which contains road model, comfort model and handling model. The comfort model contains unspring model, suspension model, spring model and assistant model. The handling model contains intention model, road cling model, press model of detent, tyre model, and so on.Secondly, subsystem controller modeling and control strategy has been completed. Suspension is given principles of vehicle yaw stability control .Front and rear different damping allocation strategy made an impact on the stability of vehicle , and the incremental yaw control PID control algorithm is given.The stability control principle of the ESP is described. The article tells the three classic PID control algorithm of the target yaw moment, and in Matlab / Simulink environment ESP and semi-active suspension control model is built.Then a detailed analysis has been done in the yaw stability and attitude control on the coupling between the semi-active suspension and ESP.The ESP-SAS integrated control strategy with a linear distribution of weight has been established. In Matlab / Simulink environment a comprehensive control unit structures based on the signs is achieved.Finally, the simulation analysis has been done. In this paper, the vehicle dynamics simulation software for light Iveco light vehicles is made to simulate on the status of the band and single-lane traffic.In low adhesion circumstances, the stability of vehicle subsystems mainly lies on the manipulation capacity of ESP.In the high-adhesion circumstances, three different ways have been used in simulation.They are semi-active suspension control ,ESP control and ESP-SAS comprehensive control. The article has also discussed the effect to the performance of vehicles in three different ways.Conclusion: On the high adhesion road, by integration control of the semi-active suspension and electronic stability program and reasonable allocation of the proportion of the two vehicles yaw control access and time respectively, it can make that the vehicles have a certain comfort and sufficient stability,at the same time, it can reduce the speed descending and the loss of power.To keep a sufficiently high speed also avoid the accident of the collision with the Vehicles travelling in the reverse direction.