Fotouli - MSc Student , Advanced Dynamic and Control Systems Lab, University of Tehran, Iran
Yousefi-Koma - Assistant professor, Advanced Dynamic and Control Systems Lab, University of Tehran, Tehran, Iran

in this study lateral instability of a railway wheelset is investigated and an active primary suspension is designed to improve the wheelset hunting phenomenon. A linear wheelset model with two degrees of freedom is used, which contains lateral and yaw motions. Parimary suspension between the wheelset and bogie frame originally consists of lateral and longitudinal consists of lateral and longitudinal springs and dampers. A lateral actuator is added to primary suspension for controlling the motions of wheelset at high speeds. Two control approaches for determining the actuator force are utilized. At frist an LQR controller has been designed and the effect of velocity variation is investigated. A model reference adaptive controller (MRAC) has also been designed for railway wheelset system to improve the system response against velocity uncertainties . both controllers can improve the instability of wheelset by governing the stability in a broader range of velocity relative to common passive system. The performance of the controllers have also been compared. One advantage of the MRAC in that system isnot designed for a fixed maximum speed. Another advanced of MRAC is its consistent quality of response. Although the wheelset remains stable using LQR controller, the quality of response alters gradually by the velocity variation.

Rail Vehicle, Stability, Active suspension, Model Reference Adaptive Control, Optimal, LQR