| With the development of automobile industry, automobile industry stands out in the economic development and becoming a backbone industry during the automobile countries. It has been happen a deep influence to the economic development of world and the improvement of society. Suspension is an important structure which influences comfort and handling abilities. Good suspension system can reduce the acceleration from anomaly roads and make it comfortable and good controlling.The suspension is the key indicators to measure performance of comfort and handling. However, the two are mutually exclusive aspects of the performance and the requirements often can not be met. How to strike a reasonable balance between the two to achieve the best results is the research of engineers. Comfort is evaluated through the general body or a body part (such as the car floor, the driver seat) the response to the acceleration. Stability control can be measured by wheel load. For example, if the lower spring stiffness will reduce vehicle acceleration so the comfort changes well, but will also lead to an increase in displacement body. The resulting changes will cause the body center change and the tire load increase which will have adverse effects on stability control; The other hand, an increase in stiffness will enhance handling and stability, but a tough spring on the road surface roughness is very sensitive and will lead to the comfort reduce. Therefore, the ideal suspension should be used in different conditions with different stiffness anddamping which is able to satisfy the requirements of the comfort the stability.Vehicles attitude reflects the two performance: vertical vibration acceleration, braking or speed up the pitch and roll of cornering mainly reflect the vehicles comfort; Roll of cornering and yaw the vehicle in motion reflect handling stability. Therefore, the study of the vehicle attitude control for the coordination of vehicle ride comfort and handling stability is of great significance.In the paper we use ACA-PI Control Algorithm to control suspension damper based on the vehicle model. It can control yaw speed across to change the damper force. 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, it adjusts the damper with ACA-PI Control Algorithm and then controls the yaw speed. The effect of PID controller depends on optimizing controlling parameter, but the parameters of traditional PID is unadjusted. This paper summarized intelligent optimization algorithm and introduced briefly the common tuning methods of PID parameters. On this base come up with the ACA-PID control algorithm that use Ant Colony Algorithm(ACA) to optimize the three parameters(KP, KI, KD) of PID controller, and use the algorithm to control vehicle yaw speed.Thirdly, Off line simulation can be used to verify the availability of control algorithm and the model. two maneuver are simulated with SIMULINK based on two-state damper, one is on straight line, the other is on turning. By studied the simulation result, we can see the influence on the vertical vibration, pitching and rolling, when we changed the damper coefficient. ACA-PI Control Algorithm isused to control yaw attitude. The result proves that the algorithm and the theory are right.Lastly, We carry on the two-state damper for a test-bed and the road test.Test and verify the damper velocity-damping characteristics for the Test and loading experiments. Damping force adjustment is done by adjusting the promoting valve and compression valve preload and screw a length. Test measured the damping value for the simulation uses, but also to provide a basis for real vehicle testing; Vehicle tests confirmed the curve measured damping the impact of the changes on vehicle handling and stability.The simulation conclusion as follows:The conclusion proves that the vehicle attitude and ride comfort can be improved on by the semi-active suspension. The vehicle yaw stability can be controlled by this new suspension when vehicle is in fast evasive maneuvers performed closed to the limit of adhesion. |
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