Seung-Bok Choi

Magnetorheological Fluid Technology : Applications in Vehicle Systems

Magnetorheological (MR) Fluid Physical Properties Potential Applications Control Strategies Semi-Active Control PID Control LQ Control Sliding Mode Control Hysteretic Behaviors of MR Fluid Preisach Hysteresis Model Identification Polynomial Hysteresis Model Identification Some Final Thoughts MR Suspension System for Passenger Vehicles Optimal Design Damping Force Control Full-Vehicle Test Some Final Thoughts MR Suspension System for Tracked and Railway Vehicles Tracked Vehicles Railway Vehicles Some Final Thoughts MR Applications for Vibration and Impact Control MR Engine Mount MR Impact Damper Some Final Thoughts MR Brake System Bidirectional MR Brake Torsional MR Brake Some Final Thoughts MR Applications for Heavy Vehicles MR Fan Clutch MR Seat Damper Some Final Thoughts Haptic Applications for Vehicles Multifunctional MR Control Knob MR Haptic Cue Accelerator Some Final Thoughts Index References appear at the end of each chapter.

Control Strategies for Vehicle Suspension System Featuring Magnetorheological (MR) Damper

Vehicle suspension is used to attenuate unwanted vibrations from various road conditions. So far, three types of suspension system have been proposed and successfully implemented; passive, active and semiactive. Though the passive suspension system featuring oil damper provides design simplicity and cost-effectiveness, performance limitations are inevitable due to the lack of damping force controllability. On the other hand, the active suspension system can provides high control performance in wide frequency range. However, this type may require high power sources, many sensors and complex actuators such as servovalves. Consequently, one way to resolve these requirements of the active suspension system is to adopt the semiactive suspension system. The semiactive suspension system offers a desirable performance generally enhanced in the active mode without requiring large power sources and expensive hardware. One of very attractive and effective semiactive vehicle suspension systems is to utilize magnetorheological (MR) fluid. MR fluids are currently being studied and implemented as actuating fluids for valve systems, shock absorbers, engine mounts, haptic systems, structure damper, and other control systems. The rheological properties of MR fluids are reversibly and instantaneously changed by applying a magnetic field to the fluid domain. Recently, a very attractive and effective semi-active suspension system featuring MR fluids has been researched widely. Carlson et al., 1996 proposed a commercially available MR damper which is applicable to on-and-off-highway vehicle suspension system. They experimentally demonstrated that sufficient levels of damping force and also superior control capability of the damping force by applying control magnetic field. Spencer Jr. et al., 1997 proposed dynamic model for the prediction of damping force of a MR damper. They compared the measured damping forces with the predicted ones in time domain. Kamath et al., 1998 proposed a semi-active MR lag mode damper. They proposed dynamic model and verified its validity by comparing the predicted damping force with the measured one. Yu et al., 2006 evaluated the effective performance of the MR suspension system by road testing. Guo & Hu, 2005 proposed nonlinear stiffness model of a MR damper. They proposed nonlinear stiffness model and verified it using simulation and experiment. Du et al., 2005

VIBRATION CONTROL OF A MULTI-STORY STRUCTURE FEATURING A SEMI-ACTIVE DOUBLE-ROD MR DAMPER

This paper presents vibration control responses of a multi-story structure installed with a semi-active magnetorheological(MR) damper. An appropriate size of the double-rod MR damper is designed and manufactured on the basis of the field-dependent Bingham model of the MR fluid. The damping force of the double-rod MR damper is evaluated with respect to the excitation frequency at various magnetic fields. After formulating the governing equation of motion for the multi-story structure associated with MR dampers, the LQR controllers to effectively suppress unwanted structural vibrations are designed by imposing semi-active actuating conditions. The control algorithms are then empirically implemented under earthquake conditions and control responses of horizontal relative displacement and acceleration are evaluated in time and frequency domains.