Stability control of railway bogies using absolute stiffness: Sky-hook spring approach

This paper presents a novel control method for the stabilization of railway bogies using a strategy based on the concept of an absolute stiffness, in which the control effort is proportional to the yaw movement of the wheelset alone. The idea can be considered as if a spring is connected between the sky and a wheelset, hence termed a 'sky-hook spring'. In this paper, the effectiveness of the control strategy is studied in detail and compared with other control solutions. It is shown that the new approach offers a number of advantages: it provides a robust control solution for the stability of railway wheelsets and there is no need for the measurement of bogie motions or the use of secondary yaw dampers. Sensing requirement can be readily met and control design is relatively simple.