Optimal Control Of Suspension And Simulation Analysis Of Vehicle Ride Comfort

Vehicle ride performance plays a significant role in the passengers'ride comfort, people recently pay more and more attention to it with the improvement of people's living as well as the automobile manufacturer, and it is also one of the most important indices in heading market competition.The research of vehicle ride performance is a full system, which is composed of road, vehicle and people. The excitation of the system which is comosed of the random vibration road and speed is transmitted by the vehicle system, which consists of the spring unit and shock absorber, for instance, tire, suspension and car seat. The output of the vehicle is the acceleration of the human sensory, it also consists of the vehicle ride performance appraising standard. Creating the random vibration road and the whole vehicle system and evaluating the vehicle's ride comfort are my thesis's three principal problems.When road surface status and car running performance change, fixed spring unit and shock absorber characteristics of traditional passive suspension will cannot improve itself at any time, which is the inherent faults of the system. The active suspension as the most advanced suspension could adjust it's stiffness and damping at any time in order to get the best vehicle ride performance and control stability. In my thesis, I employ the quadratic optimal control theory and design a optimal controller of the active suspension, which is based on the vehicle body acceleration, the suspension dynamic travel and wheels dynamic load. Through the application of optimal control theory I build a quarter vehicle model system which is based on Matlab/Simulink environment, where simulates the system. It is showed by results that not only the vehicle body acceleration is significant decreased and vehicle ride performance comfort is raised largely by the active suspension, but also the suspension dynamic travel can be well controlled.At last, a whole vehicle model is built by using the 3D software-PRO/E and the multi-body dynamics application ADAMS. Then make a movement simulation analysis based on ADAMS/View through the random vibration road, which has areadly already been built. Combining quality appraising standard evaluates the vehicle ride performance. Finally, by observing vehicle ride performance through chaning speed of the vehicle, the damping and stiffness coefficients of suspension and the road random profile inputs we find that the lower vehicle speed and stiffness coefficients of suspension could remarkably improve vehicle ride performance comfort.