Abstract
Semi-active dampers containing magnetorheological (MR) fluid are a cost effective method of implementing a controllable suspension system. A bi-viscous massspring- dashpot model of a commercially available MR damper is developed, the parameters of which have been derived empirically. It is shown how a proportional feedback control method is used to alter the force-velocity characteristics of the MR damper, using both force and acceleration feedback. The damper can be controlled to operate as a tuneable viscous device, whereby a range of linear damping rates can be achieved. The MR damper and controllers ability to track an ideal modified-skyhook force is then examined. The performance of the force feedback controllers are then examined in real-time, using both software-in-the-loop (SiL) and hardware-in-the-loop (HiL) methods. To accurately predict how the controllers perform in real-time, the dynamic characteristics of the hardware must be measured and suitable models developed to match the actual behaviour. The SiL method is used to predict the real-time dynamic behaviour of a HiL system, which includes a hydraulic test rig and MR damper. The SiL method is shown to be a flexible and cost effective means of testing and control development.
Keywords: semi-active suspension, magnetorheological damper, modified skyhook, realtime control