| Suspension system plays an important role in enhancing vehicle ride quality and handling stability and security. Magneto-rheological dampers (MRD) have been widely applied in intelligent vehicle suspension designs in the world, due to their faster response, lower energy consumption and higher reliability qualities. Nowadays, many studies have been focused on the quarter-vehicle system, in place of the full-vehicle suspension system.The primary objective of this dissertation is mainly studied in semi-active controller synthesis and analysis by establishing 7 degree-of-freedom dynamic model of the MR full-vehicle suspension system. Firstly, the adverse effects of MRD hysteresis are thoroughly analyzed on quarter-vehicle MR suspension, and a hysteresis suppression scheme is further proposed. Secondly, three kinds of road excitations are defined, such as harmonic and smooth impulse considering the time delay between front and rear wheels, as well as random white noise road excitations, suspension performances of centroid acceleration transmissibility, suspension space transmissibility and dynamic load coefficient are evaluated, through comparing the time and frequency domain responses of both passive full-vehicle suspension and MR full-vehicle suspension with zero MRD driving current, the advantages and disadvantages of suspension performances in vertical, roll and pitch motion for the MR full-vehicle suspension are systematically studied. In the end, a semi-active controller is synthesized for realizing synchronous control of the four MRDs, based on the proposed improved quarter-vehicle skyhook scheme, and the time and frequency domain responses of both MR full-vehicle suspension with the controller and zero MRD driving current are compared. The advantages and disadvantages of the proposed semi-active synchronous skyhook scheme are thus evaluated, and a theory is established for the further study of decoupling semi-active control of intelligent MR full-vehicle suspension design. |
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