In order to operate a train efficiently at high speeds regardless of the number of composed vehicles, control systems that can provide stable braking forces must be developed. In the design of brake control system, it is quite important to consider robustness because there are model uncertainties which result from nonlinear characteristics for adhesion between the wheel and rail, and the friction coefficients of brake materials. This paper will present the experimental results about the new wheel slip control, designed by the sliding mode control theory. The experiments for the proposed wheel slip control are performed while comparing some conventional control laws. The experimental results proved the effectiveness of the proposed control as compared with conventional ones, and showed the high brake performance under the nonlinear characteristics of brake dynamics.

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The MR fluid has the characteristic that the viscosity is changed by the state of the magnetic field. The MR fluid valve with the fluid has been examined as a device to expect a control valve promptly and conveniently. Generally the MR fluid valve is designed to add magnetism vertically in the direction of the flow. The reason is based on the theory that the cluster formed in the same direction as a vertical magnetic field causes flow resistance. Along the lines of this theory, varieties of MR fluid valve structures has been proposed. However, it thought that there are problems in the versatility because each structure is complicated. We manufactured some experimental MR fluid valves with a simple orifice inside, where bobbin type electromagnets apply magnetic fields. The research target is that the basic characteristics of the valves are tested with the flow characteristic test equipment and applications of the valves to practical use are examined. In this report, we explain the results that the shape of the orifice, the relative magnetic permeability of the valve material, the applied method of magnetic field etc. have on the flow characteristics. We also analyze the principle of the effect on the valves with the use of magnetic field analysis.

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