Active Suspensions

It is clear from the preceding chapters that the subject of railway vehicle dynamics has developed principally as a mechanical engineering discipline, but an important technological change is starting to occur through the use of active suspension concepts. The use of advanced control has been common for many decades in the power electronic control of traction systems, and it is now firmly established as the standard technology which has yielded substantial benefits, but its application to suspensions is much more recent. Although the term “active suspension” is commonly taken to relate to providing improved ride quality in fact, it is a generic term which defines the use of actuators, sensors, and electronic controllers to enhance and/or replace the springs and dampers that are the key constituents of a conventional, purely mechanical, “passive” suspension; as such it can be applied to any aspect of the vehicle’s dynamic system.