The Vibration Character Analysis Of Vehicle Suspension Systems And Research On The Semi-Active Control Method

At present, semi-active control suspension systems have received a great deal of attention in academe and industrial circles to improve ride comfort and road holding and handing stability. The damper with dynamically variable damping properties is one of the key elements for semi-active suspension systems. Magneto-rheological fluid dampers have recently emerged as enabling technology for implrmenting semi-active control in variety of application because of their mechanical simplicity, low operating power requirements, environmental robustness, and demonstrated potential for developing forces sufficient for applications. In the dissertation, a state-of-the-art semi-active control suspension system in which the MR dampers are used as the semi-active control actuators has been proposed and developed. The theoretically analytical and simulation are conducted to characterize the dynamical performance and to develop the semi-active control technology of the MR damping semi-active suspension system. The main parts included in the thesis are as follow:1. A review of the nonlinear dynamic modeling and semi-actve control of the vehicle suspension systems based on MR at home and abroad was given, it points out that high dofs modeling and mingle control method are current orientation and trend.2. Introduce many parameter models of magnetorheological dampers, through analyzing Sigmoid model used in the text numerically, it reveals the influence of the parameters to damper power of magnetorheological damper.3. By sine excitement, the equations of 2-dofs-suspension-system were solved by the equilibration theory, that were validated by numercal calculation. Dynamical characters in time and frequent yield and the influence of the Sigmoid model's parameters were analyzing with the suspension. The influence of the major standard of the suspension system's capability was also analyzing with the submit power that can be controlled. The basic theory of the control system design was supplied owing to the analyse of nonlinear vibration mechanism in the semi-active suspension systems.4. Building a semi-active nonlinear 8-dofs integrity suspension system model, which simulating the run on the road realitily and the the ride comfort of the motorman was considered. The nonlinear characters with the model were simulated by random excitement. 5. Building a sub control systems towards each tyre, Fuzzy control strategy was choosen with many control method. With the fuzzy control mothod, a self-compensate fuzzy strategy was builded up. The new model can see about the impart of every direction, every department in the integrity model paralleling with the passive model. Simulation was putting up not only in random excitement but also in concussion excitement. Simulation was putting up in the program of Matlab+Simulink+Toolbox. A perfect control effect reveals that the rules of the Fuzzy strategy was right.Form the results of this thesis,the nonliner dynamic behavior of the vehicle suspension using MR can be realized deeply. It sets a attempt of groping for the high dofs stucution. The result build a theoretical foundation for further study of nonliner mechanism and control of the vihicle suspension system.