Semi-active suspension that restrains lateral vibration has been mounted on some new Shinkansen vehicles in recent years, contributing to the improvement of riding comfort. The Railway Technical Research Institute (RTRI) has developed a new device with the same performance as the current one, but at a lower cost in order to facilitate its introduction to new vehicles.
      Direct pressure control using a newly-developed proportional relief valve enabled simplification of the hydraulic circuit of the variable damper and elimination of the stroke sensor in the new device (Table 1, Fig. 1). In addition, development of a low-cost acceleration sensor with a failure detection function and miniaturization / performance enhancement of the controlling device equipped with powerful CPU could achieve the same levels of safety and performance as current ones. As an example, riding comfort is improved (Fig. 2), increasing the comfort level with 3 dB reduction at a cost saving of 40%.
      Endurance tests are underway with a target of practical use from 2002.