Structure Decoupling Half Vehicle Suspension System Of Control

The controllable suspension system can improve both ride comfort and handling safety, which has become one research focus in the field of vehicle engineering since1950s. The full-car generally consists of four quarter-car suspension systems (QC) with strong coupling characteristics, which yield strong coupling effects on vertical, pitch and roll movement suspension performances. So far, an effective coordinated control method for the full-car with multiple sub-suspension systems has not been proposed. The best idea is to decouple the full-car into four independent QCs1, such that the sophisticated active or semi-active control scheme for QC suspension can be directly employed, and thus simplify the complicated controller synthesis for the full-car suspension and improve the real-time property of control system, which has important theoretical and engineering values for realizing the practical application of controllable suspension.This thesis focuses on the structural decoupling control study of half-car suspension, which has vertical and pitch movements. Firstly, the passive half-car dynamic model is established and transferred into the model involving two similar standard QC dynamic models. It is found that a coupling damping force exists in the sprung mass, and it can be compensated through adding a damping force in the unsprung mass, in which the half-car suspension could be decoupled into two independent QCs. Furthermore, a new QC suspension design with double controllable dampers is proposed on basis of the defined coupling damping force, in which the traditional passive damper is normally replaced by the sprung controllable dampe. Another damper named the unsprung controllable damper is installed between the lower control arm and linkage of vehicle controlled by the pitch angular acceleration, which plays role in compensating the yielded coupling damping force. Thus the suspension structural decoupling of half-car can be conveniently achieved and effectiveness of the proposed structural decoupling method of half-car suspension is verified. Finally, three kinds of control manners i.e., active versus active, semi-active versus active and semi-active versus semi-active, are fully discussed for the sprung and unsprung controllable dampers, respectively. The proposed active and semi-active sliding mode control schemes for the sprung controllable damper in QC are applied for the decoupling half-car suspension robust control due to the uncertainty of vehicle load, and the semi-active control manner chooses the semi-active controllable magneto-rheological damper. As a result, the proposed both active versus active and semi-active versus active control manners could achieve the ideal multi-objective suspension performances for the half-car, and the proposed structural decoupling control method can be further extended to realize coordinated control of full-vehicle suspension system with multiple sub-suspension.