Various attempts have been made from olden days on vehicles for better riding comfort and for improved maneuverability. Past vehicles have achieved vibration isolation performance, which relaxes impact from road surfaces, by means of link mechanisms and passive suspensions consisting of springs and dampers, as well as basic motion performance such as running, turning, and stopping. However, as far as passenger cars are concerned, a passive suspension has its own limitation, and the contradiction that if riding comfort is to be improved at low speeds, the maneuverability during high-speed operations becomes bad has not been solved. Demand of users has become stronger and stronger for vehicles which satisfy riding comfort and maneuverability at the same time. Moreover, as far as trains are concerned, the past technology has increased the vibration of trains as they are operated at higher speeds; thus a drop in riding comfort has been a cause for preventing high-speed operations. Nevertheless, in line with progress in mechatronic technology, active suspensions have been adopted aggressively in automobiles and trains in recent years, and attempts have been started for improving both riding comfort and maneuverability to satisfy demand of users. Some passenger cars have already appeared which are equipped with an active suspension. A similar trend is found in the case of trains; by the introduction of active suspensions, operations of trains on conventional lines at higher speeds are being started. Under these circumstances, this special issue has been created. Although high performance in vehicles may be achieved by means of active suspensions, the problem of increased energy consumption has become a serious issue, which has been brought to the fore with the bursting of the bubble. This problem seems to be solved by saying how effectively semi-active suspensions may be realized. In this special issue, new trends have been taken up, such as vehicle dynamics, design theory on active suspension systems, reduction of engine vibration by optimum design of hydraulic engine mounts, design of control systems for neural networks of semi-active suspension systems, control of variable structures of suspension systems, predictive control, magnetic levitation suspension, etc. It is hoped that these articles will be useful in future research.
Special Issue on Advanced Vehicle Dynamics and, Control