Air suspension systems are now widely used for the secondary suspension of railway vehicles. To improve the ride comfort of vehicles equipped with this system, the authors developed a semi-active damping control system of air suspension that has a flow control valve with variable orifice between an air spring and an auxiliary air chamber for Shinkansen vehicles. In order to validate the effect of vertical vibration suppression with a single vehicle model, numerical simulations, bench tests for a rolling stock test plant and running tests for a Shinkansen vehicle were conducted. Consequently, the following results were indicated. The numerical simulation using a proposed model of air spring and 5-DOF vehicle model was able to show the effectiveness of vibration suppression. Controlling both the translational vibration mode and pitching vibration mode of car body was effective in order to reduce the vertical vibration of a car body in a frequency range from 1 to 2㎐. In a running test, the system reduced the vertical vibration acceleration PSD peak value (1.4㎐) by almost 40% compared with that of the case of not using this system. Furthermore, this system was able to reduce the vibration of a car body in frequency ranges exceeding 2㎐ according to setting control parameters. In conclusion, this system was effective in reducing the vertical vibration of the Shinkansen vehicle.

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In this paper, we propose a pneumatic rubberless artificial muscle. The working principal is the same as a general McKibben artificial muscle. The rubberless artificial muscle uses an air bag made of an aluminum vapor-deposition polyester film instead of a rubber tube. The rubberless artificial muscle consists entirely of non-elastic materials. Therefore, it is necessary to design the muscle in consideration of the geometrical relationship. An expression for the design of the rubberless artificial muscle is derived. We confirmed the validity of this expression through the evaluation of a prototype. Furthermore, we examined input/output characteristics and isotonic contraction characteristics and isometric contraction characteristics of the rubberless artificial muscle as fundamental characteristics through the experiment. We confirmed that the rubberless artificial muscle efficiently converted inner pressure into generated force and contraction displacement compared with the general McKibben artificial muscle. The biomechanical characteristics of the rubberless artificial muscle are the same as a human muscle.

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Applications requiring accurate position control of cylinders are in increasing use in industry. Pneumatic cylinder systems have the potential to fulfill this requirement due to their high speed and reliability at a relatively low cost. This paper outlines a technique of repeated positioning of a pneumatic cylinder. The system runs with a sequential on-off action of air valves as its basic control algorithm. To acquire accurate positioning at the time of each operation, three proximity switches are installed for one desired stop position to detect the slider passing as well as its velocity. In this scheme, less deviation of the stop position can be obtained by braking within a certain range of velocity which can affect the positioning performance. It is experimentally suggested that there is an optimal velocity for starting to apply the braking. The results are analyzed by simulation to validate that the existence of an optimal velocity is strongly related to the frictional fluctuation and the braking characteristics. Finally, experiments of repeated positioning are conducted to show the effectiveness of the proposed braking method.

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