Control Strategy Study On Vehicle Active Suspension Based On Multi-body Dynamics Theory

Suspension system with good performance can greatly improve the dynamic quality of the vehicle. It has made a revolutionary progress after the combination with modern active control strategy and computer control technology. Concerning the vehicle system with active suspension, conventional research method concentrates only in active control strategy and structural mechanics. It uses great real system experiments to verify the theoretical result. The expense of time and cost is huge and the industrial production is also prolonged. But as the development of digital virtual prototype technology, it provides a powerful tool to rapidly design, analyze and optimize a vehicle system with active suspension.This dissertation is sponsored by the fund of the ministry of education. By use of virtual prototype technology, it changes the conventional research method of active suspension control to the design method of modern multi-body dynamic system. It reveals the dynamic characters of the vehicle system with modern intelligent control strategy and uses a wholly new philosophy to rearrange the design of active suspension system.Currently, the important trend in modern vehicle is reducing mass of the vehicle. But such reduction may give rise of intense vibration during vehicle running and deteriorate the performance quality. So it is important and urgent to research the light vehicle body dynamics. In this thesis, the vehicle body is treated as flexible body. According to Craig-Bampton analysis method of fixed boundary mode synthesizing, the flexible vehicle body is looked as a model of collection of limited element node, which moves in a linear style referencing to a floating coordinates. The floating coordinates translates and revolves in big extends in a nonlinear style. Motion of each node is approximately calculated as the addition of local linear motion. In this thesis, the finite element model is established by the powerful software ANSYS and transformed into model neutral file acceptable to the multi-body dynamics analyzing software ADAMS. Then the response motion of the mass center of the flexible vehicle-body can be worked out both in vertical and lateral direction, and the optimum...