Dynamic characteristics in the design of Maglev suspensions

The paper reviews the essential functions which apply to any kind of suspension, and distinguishes between the various inputs to which a suspension is subjected. These are used to assess the particular characteristics of an electromagnetically suspended (Maglev) vehicle, and to identify considerations which have important implications for the controller design, irrespective of the design method. Some general equations are developed which interrelate the vehicle speed, the quality of the track and the passenger comfort requirements, and these are used to identify operational conditions for which a second stage of suspension becomes necessary (that is, in addition to that provided by the magnets). The importance of understanding the suspension's response to deterministic track inputs is also highlighted. Although the paper is directed towards Maglev, the analysis is strongly based upon a consideration of the suspension transfer functions, and so many of the principles are applicable to actively controlled supensions in general.