Controlling a Rail Vehicle with Independently-Rotating Wheels

A conventional rail vehicle has a purely mechanical suspension consisting of springs and dampers. Their performance is determined mainly by spring stiffnesses, damper coefficients and the sprung and unsprung masses. As a result, the guidance forces generated at the wheel-rail contact are not optimised for a particular track curvature or profile. This leads to a contradictory requirement for a stiff suspension for guidance and a softer suspension for steering, and conventional vehicles have to be designed for a wide range of operating regimes. Active suspensions to influence the running gear of a rail vehicle have been studied widely [1] and proposed as a solution to overcoming the inherent suspension design conflict between stability and guidance. Some of this research has suggested that an active vehicle with independently-rotating wheels (IRWs) will provide the best solution in terms of vehicle performance and lower actuation requirements [2]. This paper takes this research further by designing and implementing a robust controller for IRWs on a multi-body physics simulation (MBS) model of a British Rail Class 230 D-train with modified bogies.