The damping force of Magnetorheological damper (MRD) can be controlled in a certain range by applying a steady magnetic field to reduce vehicle suspension vibration effectively. This paper presents the analysis of the damping characteristics of the twin-tube MRD, and the design of embedded control system for Twin-tube MRD used to semi-active vehicle suspension. The laws of varying damp force with current, displacement and frequency are investigated by testing for the damper, for instance the relationship curve of damping force vs. current. The control system is composed of controllable current driver and electrical control unit (ECU). ECU is developed based on MC9S12XDP512 chip. Signals that ECU acquired come from three types of sensor, i.e. digital temperature sensor, MEMS acceleration sensor and laser distance sensor embedded in MRD. The sampling frequency may exceed 400Hz. The programming is carried out in accordance with the state data acquisition and the improved On-Off control algorithm．Aiming at the high time response requirement of the MR damper, a Pulse-width modulation (PWM) current driver was designed. The hardware solutions drive circuit, interface circuit as wel1 as the software design of control system are discussed in detail. The proposed designed system has been put in actual MRD controlling application, whose test results prove its fast current response and high precision.

Aimed to satisfy damping force change requirement of vehicle MRF suspension vibration control system, a controller of MRF suspension system based on On-Off control algorithm is designed, and a control system is carried out. The system takes single chip AT90CAN128 which obey the CAN bus protocols as micro-controller, and it accomplish AD conversion of sensor signal, design of On-Off algorithm and output of PWM voltage power control signal. The system also is used in vibration control experiment of tracklayer vehicle suspension system. The experiment shows that the controller can improve control accuracy, and the control effect is obviously.

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This study presents the development of a MR damper applied to the suspension of tracked vehicles to improve the ride comfort and mobility. The MR valve is constrained to a specific cylindrical volume in order to keep the same geometry with the original damper. Radial duct is selected for its high efficiency and small volume requirement. The design rule is to enlarge the dynamic force range of the damper under the condition that the off-state force accords with the fail-safe principle. So the mechanical modeling is established and the influencing factors of adjustable coefficient are analyzed so as to determine the geometry parameters of MR valve. A set of experiments are performed to verify the theoritical analysis. The experimental results illustrate the designed MR damper has a good performance of energy dissipation and can be used to practical applications.

Magneto-rheological fluid damper(MRFD) is one of new type damper. Based on MRFD, a new model reference adaptive control(MRAC) system is designed in this paper, and it employed sky-hook damping control as model reference. Lyapunov stability theory is used to deduce adaptive control law, and simulation result indicates that MRAC system is not only can follow sky-hook control quickly and well, and it also can adapt to the road conditons, varaition of vehicle body mass and suspension system parameter