Railway bogie stability control from secondary yaw actuators

The idea of active control based upon applying a controllable yaw torque between the body and the two bogies has been studied previously, mainly to try and provide enhanced curving capability. This paper extends the idea by examining the opportunities for using secondary yaw actuators to stabilise a bogie having very soft yaw stiffness between the bogie frame and the wheelsets, the objective being to take advantage of the good curving performance offered by the soft primary yaw stiffness.