This study presents a new kind of low sedimentation magnetorheological fluid (MRF). Its salient properties are evaluated using a small-sized damper. The proposed MRF is characterized to investigate the effect of plate-like iron particles on rheological properties such as yield stress and flow behavior. Plate-like micron size iron particles play an important role in improving stability against rapid sedimentation as well as in enhancing the value of the yield stress. This study also considers a bidisperse MRF because this can produce a higher yield stress compared with a monodisperse suspension. Since the field-dependent yield stress is the key factor in mechanical applications, the physical properties of the MRF proposed in this work are evaluated and applied to the design of a small-sized damper which can be used for vibration control in washing machines. In order to verify the smaller effect on the damping force due to the particle sedimentation, the field-dependent damping forces are measured under two different operating conditions; one is just after filling the MRF and another after operating for 48 h. The proposed MRF is shown to be very effective in reducing adverse effects due to particle sedimentation.

This work presents vibration control of a vehicle suspension system using a controllable electrorheological (ER) shock absorber activated by an energy generator without external power sources. The ER shock absorber has a rack and pinion mechanism which converts a linear motion of the piston to a rotary motion. This rotary motion is amplified by gears and subsequently activates a generator to produce electrical energy. The generated voltage is experimentally evaluated with respect to excitation magnitude and frequency of the ER shock absorber. After evaluating the damping force using the regenerated voltage, a quarter-car ER suspension model is established. A skyhook controller is then formulated and experimentally implemented to attenuate vibration using the regenerated energy. It has been demonstrated via experiment that suspension vibration under bumpy and sinusoidal road conditions is significantly controlled by activating the ER shock absorber operated by the proposed regenerative energy mechanism.

2011)Integrated control on MR vehicle suspension system associated with braking and steering control, This article presents a hierarchy control strategy for magneto-rheological suspension system integrated with active braking and active front steering subsystems. This is proposed for the improvement of ride comfort and vehicle stability under different kinds of driving conditions. A nonlinear complicated full vehicle model which includes the longitudinal, lateral and vertical motions is established and combined with a modified coupling 'Magic Formula' tyre model. Subsequently, the global state identification and task assignment logic are formulated by adopting several driving conditions such as the straight driving and cornering state. A fuzzy control strategy is then used for the suspension system, while a sliding mode control technique is utilised for both braking and steering systems. In order to demonstrate the effectiveness of the proposed control methodology, control performances such as roll angle, yaw rate and vehicle trajectory are evaluated and presented.

This paper proposes a new type of magnetorheological (MR) fluid based suspension system and applies it to military vehicles for vibration control. The suspension system consists of a gas spring, a MR damper and a safety passive damper (disc spring). Firstly, a dynamic model of the MR damper is derived by considering the pressure drop due to the viscosity and the yield stress of the MR fluid. A dynamic model of the disc spring is then established for its evaluation as a safety damper with respect to load and pressure. Secondly, a full military vehicle is adopted for the integration of the MR suspension system. A skyhook controller associated with a semi-active actuating condition is then designed to reduce the imposed vibration. In order to demonstrate the effectiveness of the proposed MR suspension system, a computer simulation is undertaken showing the vibration control performance of such properties as vertical displacement and pitch angle, evaluated for a bumpy road profile.

This paper presents damping force control performances of a magnetorheological (MR) damper via a new control strategy considering hysteretic behavior of the field-dependent damping force. In order to achieve this goal, a commercial MR damper, Delphi Magneride™ which is applicable to a high-class passenger vehicle is adopted and its field-dependent damping force is experimentally evaluated. The MR damper has two types of damping force hysteretic behavior. The first is velocity-dependent hysteresis and the other is field-dependent hysteresis. Since the magnetic field is directly connected with control input, the field-dependent hysteresis largely affects the control performances of the MR damper system. To consider the field-dependent hysteretic behavior of the MR damper, a Preisach hysteresis model is established and its first-order descending (FOD) curves are experimentally identified. Subsequently, a feedforward hysteretic compensator associated with the biviscous model and inverse Bingham model is formulated to achieve the desired damping force. The control algorithm is experimentally implemented and damping force controllability for sinusoidal and arbitrary trajectories is evaluated in terms of accuracy and input magnitude. In addition, vibration control performances of the MR suspension system are experimentally evaluated with a quarter-vehicle test facility.