Study On Semi-Active Control Of Intelligent Vehicle Suspension With Magneto-rheological Dampers

Suspension system plays an important role in enhancing vehicle ride quality and handling stability, and reducing the accessory damage due to dynamic load. The conventional passive suspension system cannot satisfy all the above requirements and thus limits improvement of suspension performance because conventional passive suspension component parameters are fixed. Whereas, the semi-active suspension system can adapt to different operating conditions due to its adjustable structure parameters such as spring stiffness and damping coefficient, and thus has potential in improving the ride comfort and handling stability. The semi-active suspension performance could closely follow that of a fully active suspension and has advantages of simple structure and minimal power consumption. The study on semi-active suspension control has been widely focused by the international automobile engineering industry.This dissertation deals with the semi-active suspension control on basis of proposed Magneto-rheological (MR) damper hysteresis model and the two-degree of freedom (2-DOF) quarter-vehicle model. Three semi-active control schemes are proposed, such as modified skyhook scheme, modified relative velocity scheme, and limited relative displacement scheme. A series of excitation signals and a set of performance measures are defined, and a simulation platform is set up with Matlab Simulink to carry out the performance evaluation of the proposed different controllers, and sensitivity of the proposed controllers to variations in vehicle operating load and road roughness and controller parameters are further evaluated. The results illustrate that the proposed modified skyhook-based semi-active controller has superior robustness and could achieve desirable multi-body vehicle suspension performances.